Papers published in peer-reviewed journals
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In Press
- Zhang, Lei and David Levinson (2006) Determinants of Route Choice and
the Value of Traveler Information: A Field ExperimentA major strategy of federal ITS initiatives and
state departments of transportation is to provide traveler information
to motorists through various means, including variable message signs,
the internet, telephone services like 511, in-vehicle guidance systems,
and TV and radio reports. This is relatively uncontroversial, but its
effectiveness is unknown. Drivers receive value from traveler information
in several ways, including the ability to save time, but perhaps more
importantly, other personal, social, safety, or psychological impacts
from certainty. This information can be economically valued. The benefits
of reduction in driver uncertainty when information is provided at the
beginning of the trip by various means is the main variable we aim to
measure in this research, in which we assess user preferences for routes
as a function of the presence and accuracy of information, while controlling
for other trip and route attributes, such as trip purpose, travel time,
distance, number of stops, delay, esthetics, level of commercial development,
and individual characteristics. Data is collected in a field experiment
in which more than 100 drivers, given real-time travel time information with varying degrees
of accuracy, drove four of five alternative routes between a pre-selected
OD pair in the Twin Cities metro area. Ordinary regression, multinomial,
and rank-ordered logit models produce estimates of the value of information
with some variation. In general, results show that travelers are willing
to pay up to $1 per trip for pre-trip travel time information. The value
of information is higher for commute and event trips and when congestion
on the usual route is heavier. The accuracy of the traveler information
is also a crucial factor. In fact, there do not seem be incentives for
travelers to use traveler information at all unless they perceive it to
be accurate. Finally, most travelers (70%) prefer that such information
should be provided for free by the public sector, while some (19%) believe
that it is better for the private sector to provide such service at a
charge. Over 35% of subjects are willing to pay for OD-customized pre-trip
travel time information.
Keywords: Value of Information, Advanced Traveler Information System (ATIS), Real-Time Traffic Operations, Travel Behavior, Spatial behavior, Wayfinding Behavior, Route Choice. 06-1714, presented at the 85th Annual Meeting of the Transportation Research Board in Washington, DC, January 22-26 2006 Transportation Research Record: Journal of the Transportation Research Board (in press) - Zhang, Lei, and David M. Levinson (2005) Investing for Robustness and Reliability in Transportation NetworksAlternative transportation investment policies can lead to very different network forms in the future. The desirability of a transportation network should be assessed not only by its economic efficiency but also reliability, because the cost of incidental capacity loss in a road network can be massive. This research concerns how investment rules shape the hierarchical structure of roads, and affects network fragility with regard to natural disasters, congestion, and accidents and vulnerability to targeted attacks. A microscopic network growth model predicts the equilibrium road networks under two alternative policy scenarios: investment based on benefit cost analysis or bottleneck removal. A set of Monte-Carlo simulation runs, in which a certain percentage of links are removed according to the type of network degradation analyzed, are carried out to evaluate the equilibrium road networks. It is found that hierarchy exists in road networks for reasons such as economic efficiency, but an overly hierarchical structure has serious reliability problems. Throughout the equilibrating or evolution process, the studied grid network under benefit cost analysis has better efficiency performance, as well as error and attack tolerance. The policy implication from these findings is that benefit-cost analysis should be preferred to myopic bottleneck-removal type of investment rules, no matter how the planning horizon is specified.
Keywords: Transportation network dynamics, road growth model, reliability, vulnerability, fragility, road investment and financing policy (05-0897) presented at 84th Annual Meeting of Transportation Research Board in Washington, DC, January 9-13th 2005 and presented at 2nd International Conference on Transportation Network Reliability. Christchurch, New Zealand August 20-22, 2004. Transportation Research Record: Journal of the Transportation Research Board (in press) - Zhang, Lei and David Levinson (2004).
Ramp Metering and Freeway Bottleneck Capacity
Abstract: The objective of this study is to determine whether ramp meters increase the capacity of active freeway bottlenecks, and if they do, how. The traffic flow characteristics at twenty-seven active bottlenecks in the Twin Cities have been studied for seven weeks without ramp metering and seven weeks with ramp metering. A series of hypotheses regarding the relationships between ramp metering and the capacity of active bottlenecks are developed and tested against empirical traffic data. It is found that meters increase the bottleneck capacity by postponing and sometimes eliminating bottleneck activations (a 73% increase in the duration of the pre-queue transition period), accommodating higher (2%) flows during the pre-queue transition period, and increasing queue discharge flow rates after breakdown (3%). The two-capacity hypothesis about flow drops after breakdown was also examined and results strongly suggest the percentage flow drops at various bottlenecks follow a normal distribution (mean 5.5%, standard deviation 2.3%). The implications of these findings on the design of efficient ramp control strategies are discussed, as well as future research directions.
Keywords: Ramp metering, freeway capacity, active bottleneck, queue discharge flow, Twin Cities ramp meter shut-off Transportation Research: A Policy and Practice (in press). [bib] - Tilahun, Nebiyou Jonas, and David Levinson (2006)
A Moment of Time: Reliability in Route Choice using Stated Preference
Abstract: Understanding how reliability is valued is important because it provides insight to how aims of policies that aspire to provide better transport options can be more fully integrated with user expectations. In this study we derive a choice model for work commute trips that trades off alternatives based on the most frequent experience that users had on that route and the possibility of late or early arrival if they use a particular route. The idea of reliability is incorporated by how far the expected lateness or early arrival is from the most frequent experience on that route. We find that on route decisions the mode travel time is valued at $7.43 per hour while reduction from the magnitude of average lateness (thereby increasing the reliability of the route) is valued at $6.91 per hour.
Keywords: Travel time reliability, Stated preference, Late Penalty, Early Penalty presented at the 11th International Association of Travel Behaviour Research Conference in Kyoto, Japan August 16-20, 2006. Journal of Intelligent Transportation Systems (in press). [bib] [presentation] - Xie, Feng and David Levinson (2007) Jurisdictional Control and Network Growth.Abstract: Transport infrastructure evolves over time in a complex process as part of a dynamic and open system including travel demand, land use, as well as economic and political initiatives. As transport infrastructure changes, each traveler may adopt a new schedule, frequency, destination, mode, and/or route, and in the long term may change the location of their activities. These new behaviors create demand for a new round of modifications of infrastructure. In the long run, we observe the collective change in the capacity, service, connectivity, and connection patterns (topology) of networks. Exploring the mechanism underlying this dynamic process can answer questions such as how urban networks have developed into various topologies, which networks patterns are more efficient, and whether and how transport engineers, planners, and decision makers can guide the dynamics of land uses and infrastructure in a desired direction. This paper examines how a fixed set of places incrementally gets connected as transport networks are constructed and upgraded over time. A Simulator Of Network Incremental
Connection (SONIC) models these processes and examines how the incremental connections are actually implemented, as well as how networks evolve differently, with regard to connectivity and efficiency, under centralized versus decentralized jurisdictional control. The sensitivity of emergent topologies to some model parameters is also tested.
Keywords: Network growth, Transport economics, Incremental connection, Jurisdictional control Presented at the World Conference on Transport Research in Berkeley, California June 24-28 2007. Networks and Spatial Economics (in press) - Levinson, David, Feng Xie, Norah Montes de Oca (2006) Forecasting and Evaluating Network Growth Abstract: This research assesses the implications of existing trends on future network investment, comparing alternative scenarios concerning budgets and investment rules across a variety of performance measures. The main scenarios compare “stated decision rules”, processes encoded in flowcharts and weights developed from official documents or by discussion with agency staff, with “revealed decision rules”, weights estimated statistically based on observed historical behavior. This research specifies the processes necessary to run the network forecasting models with various decision rules. Results for different scenarios are presented including adding additional constraints for the transportation network expansion and calibration process details. We find that alternative decision rules make only small differences in overall system performance, though they direct investments to very different locations. However, changes in total budget can make a significant difference to system-wide performance. Presented at the First International Conference on Funding Transport Infrastructure in Banff, Canada August 2-3 2006. Networks and Spatial Economics (in press) [presentation]
- Xin, Wuping and David Levinson (2006) Stochastic congestion and pricing model with endogenous departure time selection and heterogeneous travelers.This paper proposes a stochastic congestion and pricing model that combines a bottleneck model with stochastic queuing to study roadway congestion and pricing. Employing this model, two pricing schemes are developed: one is omniscient pricing for which the transportation administrative agency is assumed to be aware of each and every traveler's cost structure (i.e., their detailed valuation of journey cost as well as early and late penalties), and the other is observable pricing, for which only queuing delay is considered. Travelers are characterized by their late-acceptance level and the effects of various compositions of late-averse, late-tolerant and late-neutral travelers on congestion patterns with and without pricing are discussed. Numerical simulation indicates that omniscient pricing scheme is most effective in suppressing peak hour congestion and distributing demands over longer time horizon. Also, congestion pricing is found to be more effective when travelers have diversified cost structures than identical cost structures, and congestion is better reduced with heterogeneous traveler composition than with single composition. This is consistent with earlier studies in the literature. In addition, the simulation results indicate that omniscient pricing in general reduces Expected Total Social Cost (with or without the return of the congestion fee). However, the ultimate benefits of a certain pricing scheme depend on travelers' cost structure as well as the composition of late-tolerant, late-averse and late-neutral travelers in the entire population; extreme situations such as 100% late-averse or 100% late-tolerant traveler composition deserves extra attention when analyzing different pricing schemes. presented at 11th International Conference for Hong Kong Society of Transportation Studies, December 2006. Mathematical Population Studies (in press). [poster]
- Xie, Feng and David Levinson (2007) Modeling the Growth of Transportation Networks: A comprehensive review This paper reviews the progress that has been made over the last half-century in modeling and analyzing the growth of transportation networks. An overview of studies has been provided following five main streams: network growth in transport geography; traffic flow, transportation planning, and network growth; statistical analyses of network growth; economics of network growth; and network science. In recognition of the vast advances through decades in terms of exploring underlying growth mechanisms and developing effective network growth models, the authors also point out the challenges that are faced to model the complex process of transport development.Networks and Spatial Economics (in press).
- Zhang, Lei and David Levinson (2006) Economics of Road Network Ownership Abstract: This paper seeks to understand the economic impact of centralized and decentralized ownership structures and their corresponding pricing and investment strategies on transportation network performance and social welfare for travelers. In a decentralized network economic system, roads are owned by many agencies or companies that are responsible for pricing and investment strategies. The motivation of this study is two-fold. First, the question of which ownership structure, or industrial organization, is optimal for transportation networks has yet to be resolved. Despite several books devoted to this research issue, quantitative methods that translate ownership-related policy variables into short- and long-run network performance are lacking. Second, the U.S. and many other countries have recently seen a slowly but steadily increasing popularity of road pricing as an alternative to traditional fuel taxes. Not only is the private sector encouraged to finance new roads, this transition in revenue mechanism also makes it possible for
lower-level government agencies and smaller jurisdictions to participate in network pricing and investment practice. The issue of optimal ownership s no longer a purely theoretical debate, but bears practical importance.
This research adopts an agent-based simulator of network dynamics to explore the implications of centralized and decentralized ownership on mobility and social welfare, as well as potential financial issues and regulatory needs. Components of the simulator: the travel demand model, cost functions, and key variables of pricing and investment strategies, are empirically estimated and validated. Results suggest that road network is a market
with imperfect competition. While there is a significant performance lag between the optimal strategy and the current network financing practice
in the U.S. (characterized by centralized control, fuel taxes, and budget-balancing investment), a completely decentralized network suffers
from issues such as higher-than-optimal tolls and over-investment. For the decentralized ownership structure, appropriate regulation on pricing
and investment practices is necessary. Further analysis based on simulation comparisons suggests that with appropriate price regulation, a decentralized road economy consisting of profit-seeking road owners could outperform the existing centralized control, achieve net social benefits close to the theoretical optimum, and distribute a high percentage of welfare gains to travelers. Decentralized control is especially valuable in rapidly changing environments because it promptly responds to travel demand. These results seem to favor the idea of privatizing or decentralizing road ownership
on congested networks.
Keywords: Network economics, Modeling network dynamics, Road pricing, Transportation financing, Privatization. presented at the First International Conference on Funding Transport Infrastructure in Banff, Canada August 2-3 2006. Forthcoming International Journal of Sustainable Transportation[presentation] - Iacono, Michael, David Levinson and Ahmed El-Geneidy (2008) Models of Transportation and Land Use Change: A Guide to the Territory Modern urban regions are highly complex entities. Despite the difficulty of modeling every relevant aspect of an urban region, researchers have produced a rich variety models dealing with inter-related processes of urban change. The most popular types of models have been those dealing with the relationship between transportation network growth and changes in land use and the location of economic activity, embodied in the concept of accessibility. This paper reviews some of the more common frameworks for modeling transportation and land use change, illustrating each with some examples of operational models that have been applied to real-world settings. Journal of Planning Literature Iacono, Michael, David Levinson and Ahmed El-Geneidy (2007) Models of Transportation and Land Use Change: A Guide to the Territory. Journal of Planning Literature 2008 22: 323-340.
- Levinson, David and Andrew Odlyzko (2008) Too Expensive to Meter: The influence of transaction costs in transportation and communication Technology appears to be making fine-scale charging (as in tolls on roads that depend on time of day or even on current and anticipated levels of congestion) increasingly feasible. And such charging appears to be increasingly desirable, as traffic on roads continues to grow, and costs and public opposition limit new construction. Similar incentives towards fine-scale charging also appear to be operating in communications and other areas, such as electricity usage. Standard economic theory supports such measures, and technology is being developed and deployed to implement them. But their spread is not very rapid, and prospects for the future are uncertain. This paper presents a collection of sketches, some from ancient history, some from current developments, that illustrate the costs that charging imposes. Some of those costs are explicit (in terms of the monetary costs to users, and the costs of implementing the charging mechanisms). Others are implicit, such as the time or the mental processing costs of users. These argue that the case for fine-scale charging is not unambiguous, and that in many cases may be inappropriate. Presented at Royal Society Discussion Meeting Networks: Modelling and Control. (September 2007) Philosophical Transactions of the Royal Society A: Mathematical Physical and Engineering Sciences 366(1872) pp 2033–2046 [doi] [poster] [presentation]
- Levinson, David (2007) Density and Dispersion: The Co-Development of
Land use and Rail in LondonThis paper examines the changes that occurred in the rail network and density of population in London during the nineteenth and twentieth centuries. It aims to disentangle the ”chicken and egg” problem of which came first, network or land development, through a set of statistical analyses using clearly distinguishing events by order. Using a panel
of data representing the 33 boroughs of London over each decade from 1871 to 2001, the research finds that there is a positive feedback effect between population density and network density. Additional rail stations (either underground or surface) are positive factors leading to subsequent increases in population in the suburbs of London, while additional population density is a subsequent factor in deploying more rail. These effects differ in central London, where the additional accessibility produced by
rail led to commercial development and led to a depopulation. There are also few differences in the effects associated with surface rail stations and underground stations, as the underground was able to get into central London in a way that surface rail could not. However the two networks were weak (and statistically insignificant) substitutes for each other in the suburbs, but the density of surface rail stations was a complement to the Underground in the center, though not vice versa.
Keywords: Transport, land use, London Underground, London railways, network growth, induced demand, induced supply Journal of Economic Geography 8(1) 55-57.
JEG: [Abstract], [Full text], [PDF] [doi] - Levinson, David (2007) The Orderliness Hypothesis: Does Population Density Explain the Sequence of Rail Station Opening in London?Network growth is a complex phenomenon; some researchers have suggested that it occurs in an orderly or rational way, based on the size of places that are connected. This paper examines the order in which stations were added to the London surface rail and Underground rail networks in the 19th and 20th centuries, testing to what extent that order was correlated with population density. While population density is an important factor in explaining order, this research shows that other factors are at work. The network itself helps to reshape land uses, and a network that may have been well ordered at one time, may drift away from order as activities relocate.
Keywords: Transport and land use, London Underground, network growth, railways Journal of Transport History 29(1) March 2008. - Xie, Feng and David Levinson (2008)
The Weakest Link: A Model of the Decline of Surface Transportation Networks
Abstract: This study explores the economic mechanisms behind the decline of a surface transportation network, based on the assumption that the decline phase is a spontaneous process driven by decentralized decisions of individual travelers and privatized links. A simulation model is developed with a degeneration process by which the weakest link is removed iteratively from the network. Experiments reveal how the economic efficiency of a network evolves during the degeneration process and suggest an 'optimal' degenerated network could be derived during the decline phase in terms of maximizing total social welfare.
Keywords: decline, transportation network, degeneration, welfare, accessibility 06-0760 presented at the 85th Annual Meeting of the Transportation Research Board in Washington, DC, January 22-26 2006. Transportation Research part E 44 100-113. [doi] [bib] [poster] - Levinson, David, and Wei Chen (2007)
Area Based Models of New Highway Route Growth
Abstract: Empirical data and statistical models are used to answer the question of where new highway routes are most likely to be located. High-quality land-use, population distribution and highway network GIS data for the Twin Cities Metropolitan Area from 1958 to 1990 are developed for this study. The highway system is classified into three levels, Interstate highways, divided highways, and secondary highways. Binary logit models estimate the new route growth probability of divided highways and secondary highways. Interstates, however,are not modeled here and are used as a predictor in modeling the growth of divided highways and secondary highways. The results show that the area's land-use attributes and population density level do have significant relationship with the area's likelihood of adding new highway routes.
Keywords: network growth, hierarchy of roads, land-use, population, GIS. presented at 2004 World Conference on Transport Research, Istanbul. ASCE Journal of Urban Planning and Development 133(4) 250-254. [bib] - Xie, Feng and David Levinson
(2007)
Measuring the Structure of Road Networks
Abstract: Spatial networks display both topologic and geometric variations in their structure. This study investigates the measurement of road network structure. Existing measures of heterogeneity, connectivity, accessibility, and interconnectivity are reviewed and three supplemental measures are proposed, including measures of entropy, connection patterns, and continuity. Proposed measures were applied to 16 test networks, which were derived from 4 idealized base networks: 90-degree, 45-degree, 30-degree, and completely connected. The results show that the differentiated structures of road networks can be evaluated by the measure of entropy; predefined connection patterns of arterial roads can be identified and quantified by the measures of ringness, webness, beltness, circuitness, and treeness. A measure of continuity evaluates the quality of a network from the perspective of travelers. Proposed measures could be used to describe the structural attributes of complicated road networks quantitatively, to compare different network structures, and to explore the structural evolution of networks in the spatial and temporal context. These measures can find their applications in urban planning and transportation practice.
Keywords: Networks, Transportation, Structure, Entropy, Pattern, Continuity. Geographical Analysis 39(3) pp.336-356 [bib] [doi] - El-Geneidy, Ahmed and David Levinson (2007) Mapping Accessibility Over Time Abstract: The concept of 'accessibility' has been coin in the transportation planning field for more than 40 years. Improving accessibility is a common element in the goals section in almost all transportation plans in the US. In this study we compare the changes in levels of accessibility over time in the Minneapolis - St. Paul region using two different modes (auto and transit). The importance of accessibility as a measure of land use and transportation planning performance in the region is revealed by comparing it over time. The longitudinal analysis being conducted shows improvements in most areas in the studied region in terms of the level of accessibility by automobile, and a drop in accessibility by transit over the period 1990 to 2000. The findings are compared to the levels of congestion in the region between the same time periods. This comparison shows the difference between the two measures and strengthens the importance of accessibility measures as a tool for monitoring and evaluating regional land use and transportation planning performance. Journal of Maps v2007, 76-87. [bib]
- Tilahun, Nebiyou Yonas, David M. Levinson, and Kevin J. Krizek (2007) Trails, Lanes, or Traffic: Value of Different Bicycle Facilities Using Adaptive Stated-Preference Survey 05-2023 Abstract: This study evaluates individual preferences for five different cycling environments by trading off a higher travel time as a cost incurred when choosing a better facility while letting the user have the option of selecting a less attractive facility at a lower travel time. The tradeoff of travel time to amenities of a particular facility informs our understanding of the value attached to different attributes such as bike-lanes, off-road trails, or side-street parking. The facilities considered here are off-road facilities, in-traffic facilities with bike-lane and no side street parking, in-traffic facilities with a bike-lane and side street parking, in-traffic facilities with no bike-lane and no side street parking and in-traffic facilities with no bike-lane but with parking on the side. We find that respondents are willing to travel up to twenty minutes more to switch from an unmarked on-road facility with side parking to an off-road bicycle trail, with smaller changes associated with less dramatic improvements.) Transportation Research: A Policy and Practice 41 (4) 287-301 [doi] [bib] [poster]
- Montes de Oca, Norah and David Levinson (2006) Network Expansion Decision-making in the Twin Cities Abstract: This paper presents a qualitative analysis of the decision-rules used by jurisdictions in Minnesota's Twin Cities metropolitan area. Interviews were conducted with staff at the city, county, metropolitan, and state levels to determine how decisions about road investment, expansion and new construction were made. Flowcharts were developed to provide a more systematic way of presenting that information. Most jurisdictions do not have extensive public participation processes, though several, notably the Metropolitan Council, Hennepin and Ramsey Counties and the City of Minneapolis do. Jurisdictions with public participation have the most formal and extensive documentation of their investment decision process. The decision factors vary by jurisdiction, though safety, capacity, and pavement quality were important throughout. Journal of the Transportation Research Board: Transportation Research Record#1981 (Planning and Analysis 2006) pp 1-11 [ISBN: 0309099919] [bib]
- Zou, Xi and David Levinson (2006) Modeling Pipeline Driving Behaviors: A Hidden Markov Model Approach Abstract: Driving behaviors at intersection are complex because drivers have to perceive more traffic events than normal road driving and thus are exposed to more errors with safety consequences. Drivers make real-time responsesin a stochastic manner. This paper presents our study using Hidden Markov Models (HMM) to model driving behaviors at intersections. Observed vehicle movement data are used to build up the model. A single HMM is used to cluster the vehicle movements when they are close to intersection. The re-estimated clustered HMMs provide better prediction of the vehicle movements compared to traditional car-following models. Only through vehicles on major roads are considered in this paper. Journal of the Transportation Research Board: Transportation Research Record #1980 (Driver Behavior, Older Drivers, Simulation, User Information Systems, and Visualization) pp. 16-23. [ISBN: 0309099900] [bib]
- Smalkoski, B., Ning Li, and David Levinson (2006) Economic Effects of Lifting the Spring Load Restriction Policy in Minnesota Abstract: Spring load restrictions (SLR) regulate the weight per axle carried by heavy trucks during the spring thaw period. This policy aims to reduce pavement damage caused by heavy vehicles and extend the useful life of roads, but it also imposes costs on the trucking industry due to detouring or increased number of truckloads. Although the policies have been implemented for many years, their resulting economic effect has been unclear. The Minnesota Local Road Research Board (LRRB) and the Minnesota Department of Transportation (Mn/DOT) sponsored a cost/benefit study of spring load restrictions in Minnesota. The study, based on the results of surveys of industry costs, a pavement performance model, and a freight demand model, concludes that the benefits of lifting the existing SLR policy outweigh the additional costs. Roadways operating at 5-tons require additional study; however, current analysis warrants repealing SLR and keeping roadways operating year-round at 9-tons. The cost of additional damage should be recovered from those who benefit from the change in policy. Journal of the Transportation Research Forum 45(2) pp. 45-56. [bib]
- Zou, Xi and David Levinson (2006)
A Multi-Agent Congestion and Pricing Model
Abstract: A multi-agent model of travelers competing to utilize a roadway in time and space is presented in this paper to illustrate the effect of congestion and pricing on traveler behaviors and network equilibrium. To realize the spillover effect among travelers, N-player games are constructed in which the strategy set include (N+1) strategies. We solve the N-player game (for N ≤ 7) and find Nash equilibria if they exist. This model is compared to the bottleneck model. The results of numerical simulation show that the two models yield identical results in terms of lowest total costs and marginal costs when a social optimum exists.
Keywords: Agent-based Model, Game Theory, Congestion, Queueing, Traffic Flow, Congestion Pricing, Road Pricing, Value Pricing Transportmetrica Vol.2, No.3, 2006 pp.237-249. [bib] [poster] - Levinson, David and Lei Zhang (2006)
Ramp Meters on Trial: Evidence from the Twin Cities Metering Holiday
Abstract: Ramp meters in the Twin Cities have been the subject of a recent test of their effectiveness, involving turning them off for 8 weeks. This paper analyzes the resultswith and without ramp metering for several representative freeways during the afternoon peak period. Seven performance measures: mobility, equity, productivity, consumers' surplus, accessibility, travel time variation and travel demand responses are compared. It is found that ramp meters are particularly helpful for long trips relative to short trips.Ramp metering, while generally beneficial to freeway segments, may not improve trip travel times (including ramp delays). The reduction in travel time variation comprisesanother benefit from ramp meters. Non-work trips and work trips respond differently to ramp meters. The results are mixed, suggesting a more refined ramp control algorithm,which explicitly considers ramp delay, is in order.
Keywords: Ramp Meters, Evaluation, Equity, Mobility, Accessibility, Productivity, Consumers' Surplus, Travel Time Variation, Travel Demand Transportation Research: A Policy and Practice Volume 40, Issue 10 , December 2006, Pages 810-828. [doi] [bib] - Levinson, David and Bhanu Yerra (2006)
Self Organization of Surface Transportation Networks
Abstract: This research investigates the self-organization of surface transportation networks. Using a travel demand model coupled with revenue, cost, and investment models, experiments are run under a variety of parameters on a grid network. It is found that roads, contiguous sections of multiple links operating with similar characteristics, and hierarchies of roads emerge under a broad range of assumptions from networks with neither defined roads nor clearly organized hierarchies. The factors which drive this are the (dis)economies of scale, the presence of boundaries, and any initial asymmetry in the network. This research thus finds that roads and hierarchies, which are often thought to be the product of conscious design, can also arise without such intention.
Keywords: Self-organization, network growth, network evolution, transportation planning Transportation Science Vol. 40 No. 2 May 2006 pp. 179-188 [doi] [bib] - Chen, Wenling and David Levinson (2006)
Effectiveness of Learning Transportation Network Growth Through Simulation
Abstract: Computer simulation plays an increasingly important role in engineering education as a tool for enhancing classroom learning. This research investigates the efficacy of using simulation in teaching the topic of transportation network growth through an experiment conducted at the Civil Engineering Department of the University of Minnesota. In the experiment, a network growth simulator program (SONG) was incorporated into a senior/graduate class in transportation system analysis. Results of the experiment show that the use of SONG effectively enhanced students' learning in terms of helping students develop in-depth understanding about the development process of network patterns, and helped them develop some aspects of judgment, problem-solving, and decision-making skills. However the use of SONG may have been more effective had some other barriers to learning been overcome.
Keywords: Simulation, Engineering Education, and Transportation Network Growth. ASCE Journal of Professional Issues in Engineering Education and PracticeVol. 132, No. 1, January 1, 2006. [doi] [bib] [poster] - Levinson, David, Kathleen Harder, John Bloomfield, Kathy Carlson (2006)
Waiting Tolerance: Ramp Delay vs. Freeway Congestion
Abstract: Waiting tolerance at ramp meters and travel time on the freewaywere measured using a computer administered stated preference (CASP) survey and a virtual experience stated preference (VESP) methodemploying a driving simulator.The selections varied in the number of minutes waiting at a ramp meter with vehicle speed once on the freeway. The subjects ranked the selections in order of preference. The results were statistically analyzed using a binary logit model controlling for demographics, socioeconomic characteristics, daily travel time, and personality scores.The results by the CASP method displayed a preference for freeway congestion to ramp delay, but opposite results were obtained by the VESP method. A number of reasons are posited to explain the difference, but the results indicate that method of stated preference data collection can significantly affect conclusions drawn.
Keywords: Ramp meters; Personality; Stated preference; Driving simulator; Travel time Transportation Research part F: Traffic Psychology and Behaviour Volume 9, Issue 1 , January 2006, Pages 1-13. [doi] [bib] - Zhang, Lei and David Levinson (2005)
Balancing Efficiency and Equity of Ramp Meters
Abstract: A new freeway ramp control objective - minimizing total weighted travel time is presented in this study. This new objective function is capable of balancing efficiency and equity of ramp meters, while the previous metering objective - minimizing total absolute travel time is purely efficiency-oriented and hence produces a most efficient but least equitable solution. When certain assumptions hold, this metering objective is shown to be equal to minimizing non-linearly weighted ramp delay. A simulation method to achieve the new metering objective is developed and demonstrated using the example of BEEX, a new ramp control strategy also developed in this study, in a microscopic traffic simulator.
Keywords: Ramp Metering, Efficiency, Equity, BEEX, Value of travel time ASCE Journal of Transportation Engineering 131(6) pp.477-481. [doi] [bib] - Yerra, Bhanu and David Levinson (2005) The Emergence of Hierarchy in Transportation Networks Abstract: A transportation network is a complex system that exhibits the properties of self-organization and emergence. Previous research in dynamics related to transportation networks focuses on traffic assignment or traffic management. This research concentrates on the dynamics of the orientation of major roads in a network andabstractly models these dynamics to understand the basic properties of transportation networks. A model is developed to capture the dynamics that leads to a hierarchicalarrangement of roads for a given network structure and land use distribution. Localized investment rules - revenue produced by traffic on a link is invested for that link's own development - are employed. Under reasonable parameters, these investment rules, coupled with traveler behavior, and underlying network topology result in the emergenceof a hierarchical pattern. Hypothetical networks subject to certain conditions are tested with this model to explore the network properties. Though hierarchies seem to be designed by planners and engineers, the results show that they are intrinsic properties of networks. Also, the results show that roads, specific routes with continuous attributes, are emergent properties of transportation networks.. Annals of Regional Science 39(3) pp. 541-553. [doi] [bib] [poster]
- Zhang , Lei and David Levinson (2005)
Road Pricing with Autonomous Links
Abstract: This research seeks to examine road pricing on a network of autonomous highway links. By autonomous it is meant that the links are competitive and independent, with the objective of maximizing their own profits without regard for either social welfare or the profits of other links. The principal goal of the research is to understand the implications of adoption of road pricing and privatization on social welfare and the distribution of gains and losses. The specific pricing strategies of autonomous links are evaluated first under the condition of competition for simple networks. An agent-based modeling system is developed which integrates an equilibrated travel demand, route choice, and travel time model with a repeated game of autonomous links setting prices to maximize profit. The levels of profit, welfare consequences, and potential cooperative arrangements undertaken by autonomous links will be evaluated. By studying how such an economic system may behave under various circumstances, the effectiveness of road pricing and road privatization as public policy can be assessed.
Keywords: Network dynamics, road pricing, autonomous links, privatization, agent-based transportation model Journal of the Transportation Research Board #1932 pp. 147-155. [bib] - Levinson, D (2005)
Paying for the Fixed Costs of Roads
Abstract: This paper explores alternative financing mechanisms to pay for the fixed costs of roads, particularly in cases without rising marginal costs. Mechanisms considered include tolls, gas taxes, and developer payments. The problems with each are discussed. An example looking at problems of temporal and spatial free-riding is presented.
Keywords: Transportation financing, economics, toll roads, impact fees . Journal of Transport Economics and Policy, Volume 39, Part 3, September 2005, pp. 279-294. [bib] - Levinson, David (2005)
Micro-foundations of Congestion and Pricing: A Game Theory Perspective
Abstract: This paper develops congestion theory and congestion pricing theory from its microfoundations, the interaction of two or more vehicles. Using game theory, with a two-player game it is shown that the emergence of congestion depends on the players-relative valuations of early arrival, late arrival, and journey delay. Congestion pricing can be used as a cooperation mechanism to minimize total costs (if returned to the players). The analysis is then extended to the case of the three-player game, which illustrates congestion as a negative externality imposed on players who do not themselves contribute to it.
Keywords: Game Theory, Congestion, Queueing, Traffic Flow, Congestion Pricing,Road Pricing, Value Pricing. Transportation Research part A Volume 39, Issues 7-9 , August-November 2005, Pages 691-704. [doi][bib] - Levinson, D, and Yao Wu (2005) The Rational Locator Re-examined Abstract: The Rational Locator Hypothesis posits that individuals can, if they choose, maintainapproximately steady journey-to-work travel times by adjusting their home and workplace. This hypothesis was coupled with the observation of long-term stability indrive alone journey-to-work times in metropolitan Washington (those times were unchanged from 1957 through 1968 to 1988). Despite the increase of averagecommuting distance and congestion, trip duration remained constant or even declined when controlling for travel purpose and travel mode because of shifting a share of traffic from slow urban routes to faster suburban routes. This observation has significance, as it is important to know for travel demand analysis if there is an underlying budget, or even a regularity, as this helps us determine whether our forecasts are reasonable. To retest the underlying rationale for the hypothesis: that travel times are stable, both intra-metropolitan and inter-metropolitan comparisons of travel times are made. The intra-metropolitan analysis compared Washington DC data from 1968, 1988, and 1994, and Twin Cities data from 1990 and 2000. The results depend upon geography. For the larger Washington DC region, keeping the same geography shows little change in commute times, but using the larger 1994 area suggests an increase in commute times.However, the Twin Cities, starting from a much shorter commute time, shows a marked increase over the decade, using either the smaller or the larger geography. To explain the differences between the two areas, an inter-metropolitan analysis conducts a series of regressions on mean metropolitan travel time for the 65 largest metropolitan areas in theUnited States. The average commute time varies (positively) in these cities as a function of congestion and population density-both significant at the 99% confidence interval.Geographical area, population, and income were also significant at the 90% confidence interval. Despite the continuing observation of stability in drive alone commuting timesin metropolitan Washington, we reject the theory of personal commuting budgets, as we find that not only are commuting times not generally stable over time at the intra-metropolitan area, but that commuting time clearly depends on metropolitan spatial structure. Transportation 32 187-202. [doi][bib] [presentation]
- Krizek, K. and David Levinson (2005) Teaching Integrated Land Use-Transportation Planning: Topics, Readings, and Strategies Abstract: Planning pedagogy is increasingly focused on ways to teach interdisciplinary topics in an integrated and synergistic manner. The intersection of land use and transportation represent two topics that, in recent years, have risen front and center for the planning profession as a whole as well as for individual program specialization areas. This article focuses on the manner in which planning programs and in particular, specific courses, address land use and transportation planning. After describing the context in which such courses exist (e.g., program specializations, faculty size), the bulk of this analysis centers on analyzing syllabi from 15 courses in North American planning programs that squarely address integrated land use-transportation planning. The syllabi are analyzed in two respects. The first examines the list of topics covered within each course. The nature of primary, secondary, and peripheral topics (as assessed by the frequency in which they appear in the syllabi) are discussed. Second, the analysis uncovers the frequency in which specific readings are used in each course (articles, book chapters, books). Special attention is devoted to discussing the substance (e.g., what topics), origin (e.g., journal name), and/or the availability of key readings. The article closes by discussing the detailed nature of a sample land use-transportation course from the Urban and Regional Planning Program at the University of Minnesota in which there is a lecture and laboratory component.. Journal of Planning Education and Research 24(3) pp. 304-316. [doi][bib]
- Smalkoski, Brian, and David Levinson (2005) Value of Time for Commercial Vehicle Operators Abstract: The spring load restriction policy of Minnesota has been in effect for over 50 years with little consideration given to the cost that it imposes on the freight industry. A cost-benefit study was recently commissioned to examine the policy. The cost-benefit analysis required a precise estimate of the value of time for commercial vehicle operators in Minnesota. An estimate was not available from previous studies, or from previous data. The necessary revealed preference (RP) information does not exist, and relevance of previous studies was questioned based on the differences in geographic location and the age of data used to construct the estimates. A sample was constructed from several trucking industry sources to conduct a survey. Interviews were conducted using an adaptive stated preference (ASP) survey to derive an estimate to the nearest dollar. A tobit model was fit to the data from the interviews to derive the estimate for value of time. A mean of $49.42 was found, with a 95% confidence interval from $40.45 to $58.39. Variation in the distribution of values is largely undetermined, with the exception of fleet operation, whether it is a for-hire truck fleet, or a private truck fleet.. Journal of the Transportation Research Forum. 44:1 89-102. [bib] [poster]
- Levinson, David and Peter Rafferty (2004) Delayer Pays Principle: Examining Congestion Pricing with Compensation Abstract: Despite its virtues, congestion pricing has yet to be widely adopted. This paper explores the issues of equity and use of toll revenue and several possible alternatives. The equity and efficiency problems of conventional (uncompensated) congestion pricing are outlined. Then, several alternatives are discussed and developed. A new compensation mechanism is developed, called the delayer pays principle. This principle ensures that those who arecause delay to others pay a toll to compensate those who are delayed. We evaluate the effectiveness of this idea by simulating alternative tolling approaches and evaluating the results across several measures, including delay, social cost, consumer surplus, and equity. Different tolling approaches can satisfy widely varying policy objectives, thus this principle is applicable in diverse situations. Such a system is viable and can eliminate some common hurdles of congestion pricing while remaining revenue neutral. International Journal of Transport Economics 31:3 295-311 [bib] [poster] [presentation]
- Levinson, David, Kathleen Harder, John Bloomfield, and Kasia Winiarczyk. (2004) Weighting Waiting: Evaluating the Perception of In-Vehicle Travel Time Under Moving and Stopped Conditions Abstract: This paper describes experiments comparing traditional computer administered stated preference with virtual experience stated preference to ascertain how people value stopped delay compared with stop-and-go or freeflow traffic. The virtual experience stated preference experiments were conducted using a wrap around driving simulator. The two methods produced two different results, with the traditional computer assisted stated preference suggesting that ramp delay is 1.6 to 1.7 times more onerous than freeway time, while the driving simulator based virtual experience stated preference suggested that freeway delay is more onerous than ramp delay. Several reasons are hypothesized to explain the differences, including recency, simultaneous versus sequential comparison, awareness of public opinion, the intensity of the stop-and-go traffic, and the fact that driving in the real-world is a goal directed activity. However without further research, which, if any, of these will eventually prove to be the reason is unclear. What is clear is that a comparison of the computer administered stated preference with virtual experience stated preference produces different results, even though both procedures strive to find the same answers in nominally identical sets of conditions. Because people experience the world subjectively, and make decisions based on those subjective experiences, future research should be aimed at better understanding the differences between these subjective methodologies. Transportation Research Record: Journal of the Transportation Research Board #1898 pp. 61-68 [bib] [poster] [presentation]
- Levinson, David, Ning Li, Xi Zou, Brian Smalkoski, and Maryam Hashami (2004)
A Framework for Analyzing the Effects of Spring Load Restriction
Abstract: Spring Load Restrictions (SLR) impose load restrictions on heavy trucks during the spring thaw period. Although the policies have been implemented for many years, we are still unsure of their economic effects on truckers. This paper overviews practices around the world and sets up a framework to estimate the Benefit/Cost of the SLR policy. A freight demand model in Minnesota was built to estimate the impacts of SLR on the freight transportation pattern. The model allows various policy scenarios to be tested before being tested in practice. A preliminary result of the freight demand model shows the SLR policy increased truck Vehicle Kilometers of Travel (VKT) in Lyon County, Minnesota by about 13 percent.
Keywords: Spring load restrictions, Benefit/Cost analysis, EMME/2, Freight demand model Journal of the Transportation Research Board No.1874 181-188 [bib] - Zhang, Lei and David Levinson. (2004a)
An Agent-Based Approach to Travel Demand Modeling: An Exploratory Analysis
Abstract: The paper develops an agent-based travel demand model. In this model, travel demands emerge from the interactions of three types of agents in the transportation system: node, arc and traveler. Simple local rules of agent behaviors are shown to be capable of efficiently solving complicated transportation problems such as trip distribution and traffic assignment. A unique feature of the agent-based model is that it explicitly models the goal, knowledge, searching behavior, and learning ability of related agents. The proposed model distributes trips from origins to destinations in a disaggregate manner and does not require path enumeration or any standard shortest-path algorithm to assign traffic to the links. A sample 10-by-10 grid network is used to facilitate the presentation. The model is also applied to the Chicago sketch transportation network with nearly 1000 trip generators and sinks, followed by a discussion of possible calibration procedures. The agent-based modeling techniques provide a flexible travel forecasting framework that facilitates the prediction of important macroscopic travel patterns from microscopic agent behaviors, and hence encourages the studies on individual travel behaviors. Future research directions are identified, as are the relationship between the agent-based and activity-based approaches for travel forecasting.
Keywords: Travel forecasting, Agent-based model, Travel behavior, Trip distribution, Traffic assignment, Shortest path algorithm, Activity-based model Transportation Research Record: Journal of the Transportation Research Board #1898 pp. 28-38 [bib] - Zhang, Lei and David Levinson (2004b)
Optimal Freeway Ramp Control without Origin-Destination Information
Abstract: This paper develops an analytical framework for ramp metering, under which various ramp control strategies can be viewed as ramifications of the same most-efficient control logic with different threshold values, control methods, and equity considerations. The most-efficient control logic only meters the entrance ramps nearest critical freeway mainline sections so as to eliminate freeway internal queues, which is derived from a new formulation of the optimal ramp control problem. Instead of assuming the availability of real-time origin-destination information, the new formulation takes advantages of the stability and predictability of off-ramp exit percentages. Those properties of the off-ramp exit percentages are supported by empirical data, and allow us to formulate the optimal ramp control problem as a linear program whose input variables are all directly measurable by detectors in real-time. The solution is also tested on a real-world freeway section in a microscopic traffic simulator for demonstration. Time-dependent origin/destination tables and off-ramp exit percentages are compared as two alternative ways to represent the true real-time demand patterns that are important to freeway ramp metering.
Keywords: Ramp metering, Freeway operations, OD table, Off-ramp exit percentage Transportation Research part B Volume 38, Issue 10, December 2004, Pages 869-887. [doi] [bib] - Zhang, Lei and David Levinson (2004c)
Some Properties of Flows at Freeway Bottlenecks
Abstract: Capacity of a freeway segment should only be measured when it is an active bottleneck. The properties of flows at active freeway bottlenecks bear on both the definition of capacity and the procedure of capacity analysis. Past studies have examined the flow features at bottlenecks on several freeways in Toronto, Ontario, and San Diego, California. This study examined twentyseven active bottlenecks in the Twin Cities metro area, Minnesota, for a seven-week period. The analysis focuses on the properties of pre-queue transition flows (PQF) and queue discharge flows (QDF) averaged across various time intervals (thirty-second, daily average, and long-run average). It is found that the percentage flows drop after upstream queues form at all studied bottlenecks range from 2 percent to 11 percent. The 30-second QDFs display high variation and should not be assumed to be constant. The daily average QDFs at each studied bottleneck follows a normal distribution based on two normality tests and visual inspection of the normal probability plot. Results also suggest that the long-run average QDFs (mean 2016 pc/ln/hr) and PQFs (mean 2124 pc/ln/hr) are both normally distributed. The implication of these empirical findings on capacity estimation is also discussed.
Keywords: freeway capacity, active bottleneck, queue discharge flow, pre-queue transition flow Journal of the Transportation Research Board No. 1883 122-131. [bib] - Das, Shantanu and David Levinson (2004) A Queuing and Statistical Analysis of Freeway Bottleneck Formation Abstract: A modified approach to treat traffic flow parameters (flow, density and speed) has been introduced in this paper. A queuing analysis has been conducted on traffic flow data on Interstate 94 in the Minneapolis-St. Paul metro area. A methodology has been developed to calibrate loop detector count data. Corrected flow data has been subjected to analysis using queuing analysis to compute densities and speeds on freeway sections. Statistical analysis identifies 'active bottleneck' locations on freeways and sections where bottlenecks occur because of disturbances caused by downstream bottlenecks propagating backwards in the form of shockwaves. A sample of six days on Interstate 94 was considered for the analysis. Our analysis reveals that the same section cannot always be characterized as a 'bottleneck' location; at some times it is active and at others, it is subject to downstream bottlenecks. Traffic flow characteristics change and that leads to changing situations on each freeway section. ASCE Journal of Transportation Engineering Vol. 130, No. 6, November/December 2004, pp. 787-795. [doi] [bib]
- Krizek, Kevin, Amanda Birnbaum, and David Levinson (2004) A Schematic for Focusing on Youth in Investigations of Community Design and Physical Activity Abstract: This paper provides a first step to address special considerations for youth in a relatively new area of physical activity research. After reviewing the urgent need for novel approaches to increasing physical activity, the growing interest in the effects of community design is discussed. Although most discussion on this topic has focused on adults, there are important differences between youth and adults that warrant a special focus on youth and need to be accounted for. This article presents a schematic that accounts for how and where youth spend their time, decomposing the day into time spent in travel and time spent at destinations, and identifying portions of those times that are spent engaged in physical activity. By focusing on both spatial and behavioral dimensions of youth time, the schematic may help organize and advance scientific inquiry into the relationships between community design and physical activity specifically for youth.. American Journal of Health Promotion19:1 33-38. [bib] [poster]
- Levinson, David (2003)
The Next America Revisited
Abstract: This paper examines Columbia, Maryland, called "The Next America" by its founders in 1967. It compares the planning goals and actual achievements over the third of a century that the city has existed. The physical plan and social plan are discussed in turn, and their reinforcing aspects considered. Issues of community and identity, racial integration, education, religion, transportation, shopping, work, and parks are addressed. Many of the goals have been achieved; others have fallen short or evolved over time.
Keywords: Columbia, Maryland; Master Planned Community; New Town; James Rouse. Journal of Planning Education and Research Summer 2003, Volume 22, Number 4, pp. 329-345. [doi] [bib] - Levinson, David (2003)
The Value of Advanced Traveler Information Systems for Route Choice
Abstract: Over the next few years, driver behavior should become more informed with the advent and deployment of in-vehicle navigation systems. This paper analyzes systems that provide the driver the fastest path between his or her current location and final destination, updated in real-time to consider recurring and non-recurring congestion. The traveler's full cost per trip is a bundle comprised of both expected travel time and its reliability. This paper explores these topics from a theoretical economic perspective and then simulates stylized cases. Simulation results indicate that typical information benefits are at a maximum on the precipice of congestion, when vehicles are arriving at a rate of 95% of the capacity, while non-recurring congestion benefits are much greater.
Keywords: Transportation Information Systems, In-Vehicle Navigation, En-Route Guidance, Electronic Route Guidance, Advanced Traveler Information Systems , Transportation Research part C 11(1) 75-87. [doi] [bib] - Levinson, David and Elva Chang (2003) A Model for Optimizing Electronic Toll Collection Systems Abstract: This paper examines the deployment of electronic toll collection (ETC) and develops a model to maximize social welfare associated with a toll plaza. A payment choice model estimates the share of traffic using ETC as a function of delay, price, and a fixed cost of acquiring the in-vehicle transponder. Delay in turn depends on the relative number of ETC and Manual Collection Lanes. Price depends on the discount given to users of the ETC Lanes. The fixed cost of acquiring the transponder (not simply a monetary cost, but also the effort involved in signing up for the program) is a key factor in the model. Once a traveler acquires the transponder, the cost of choosing ETC in the future declines significantly. Welfare depends on the market share of ETC, and includes delay and gasoline consumption, toll collection costs, and social costs such as air pollution. This work examines the best combination of ETC Lanes and toll discount to maximize welfare. Too many ETC lanes cause excessive delay to non-equipped users. Too high a discount costs the highway agency revenue needed to operate the facility. The model is applied to California's Carquinez Bridge, and recommendations are made concerning the number of dedicated ETC lanes and the appropriate ETC discount, Transportation Research part A 37(4) 293-314. [doi][bib] [poster]
- Levinson, David and Ramachandra Karamalaputi(2003) Predicting the Construction of New Highway Links Abstract: This paper examines new highway construction based on the status of the network, traffic demand, project costs, and budget constraints. The data span two decades and consist of descriptions of physical attributes of the network, the construction and expansion history, and average annual daily traffic values on each of the links. An algorithm is developed to designate adjacent and parallel links in a large network. A nonlinear cost model for new construction and highway expansion is developed for the Minneapolis-St. Paul metropolitan area. Results show that new links providing greater potential access are more likely to be constructed and that more links will be constructed when the budget is larger, which supports the underlying economic theory. The models developed here have important implications for planning and forecasting, allowing us to predict how networks might be altered in the future in response to changing conditions. . Journal of Transportation and Statistics Vol. 6(2/3) 81-89. [bib]
- Levinson, David and Ramachandra Karamalaputi (2003),
Induced Supply: A Model of Highway Network Expansion at the Microscopic Level
Abstract: This paper examines the growth of a network based on the present conditions of the network, traffic demand, other demographic characteristics, project costs, and a budget constraint. The effects of expanding a link on its upstream and downstream neighbors, as well as on parallel links are also considered. Data spans two decades and consists of data on physical attributes of the network, their expansion history and AADT values on each of the links. A non-linear cost model is developed for the Twin Cities Metropolitan Area. Results show that high capacity links are more likely to be expanded and a higher budget result in more links being expanded. Large population in the surrounding region deters two-lane expansion because of the high cost associated with such an expansion but a one-lane expansion is favored. One of the important results of this research is that the rate of network expansion has decreased over the years.
Keywords: Network expansion, Cost Model, Transportation forecasting, adjacent links in a network. Journal of Transport Economics and Policy, Volume 37, Part 3, September 2003, pp. 297–318. [bib] - Levinson, David (2003)
Perspectives on Efficiency in Transportation
Abstract: This paper considers the engineer's, economist's, manager's, and planner's perspectives on effectiveness for transportation respectively. This paper examines both the measures used in each perspective, weighs their advantages and disadvantages for various purposes. The first section summarizes various measures of mobility that are used to assess transportation. This is followed by an exposition of transportation consumer surplus and its limitations. Similar treatment of accessibility and productivity are provided. The conclusions call for consideration of equity and for taking the subjective point of view of the traveler rather than the "objective" point of view of the omniscient planner/engineer/economist/manager.
Keywords: Performance Based Programming, Performance Measures, Systems Evaluation, Measures of Effectiveness, Mobility, Utility, Benefit-Cost, Productivity, Accessibility . International Journal of Transport Management 1 pp.145-155. [doi] [bib] [presentation] - Muthuswamy, Satya and David Levinson (2003)
Buying into the Bypass: Allowing Trucks to pay to use the Ramp Meter Bypasses
Abstract: People make their route choices based on the delays they experience but not on the delays they impose on others. Moreover different travelers have different values of time. Road Pricing can be seen as the means to optimize the use of a roadway by charging each traveler the cost he imposes on others. This paper analyzes the opening of an HOV ramp meter bypass to trucks that pay a toll. Trucks are similar to HOV as both have a higher value of time than a single occupant car. Thus, by saving time for these vehicles the system stands to gain. The toll to be set was estimated under three scenarios - user benefit maximization, profit maximization and system benefit maximization. A queue was simulated, and based on the decision criteria the optimal toll was determined. It is found that to maximize the system welfare, the high Value of Time vehicles like trucks should be allowed to use the bypass for free, but that raises some equity and operational issues. However a toll that allows trucks to use the bypass improves the welfare over simply prohibiting the trucks from the bypass.
Keywords: Trucks, HOV, Ramp Meter, Pricing . Journal of the Transportation Research Forum Published in Transportation Quarterly 57(1), Winter 2003 pp. 81-92. [bib] - Parthasarathi, Pavithra, David Levinson, and Ramachandra Karamalaputi (2003) Induced Demand: A Microscopic Perspective Abstract: This paper analyzes the induced demand hypothesis using a disaggregate approach at the link level. A panel data set of Minneapolis/Saint Paul highway network for the years 1980-1998 is constructed. A model that predicts the traffic flow on the link in terms of Vehicle Kilometers Traveled (VKT) based on the flow and capacity conditions existing on the link in the previous years is specified and estimated. The flow and capacity conditions existing on the identified neighboring parallel links are also taken into account. Socio-demographic characteristics like population of the Minor Civil Division (MCD) to which the link belongs and the surrounding MCDs are also considered. The results indicate that capacity enhancements in the previous years, given by lane additions have a positive and significant effect on the VKT of the link, confirming the induced demand hypothesis. The elasticities are lower than reported in previous research, indicating the importance of separating new construction from the expansion of existing links. Urban Studies Volume 40, Number 7 June 2003 pp. 1335-1353. [doi] [bib] [poster]
- Levinson, David and Bhanu Yerra (2002) Highway Costs and the Efficient Mix of State and Local Funds Abstract: Transportation networks and governments are both hierarchically organized. In some states most highways are financed by state governments, while in other states similar roads are financed locally. Larger governments attain scale economies. However they also tend to be more bureaucratic and have higher operating costs, all else equal, due to problems such as span of control. This study relates highway expenditure with share of expenditure by state government so that a basis for determining how governments should share expenditure on all roads in a state to attain efficiency in highway costs. For each state three different costs are considered: capital outlay, operations and maintenance, and total costs. Two government layers are considered: state (including federal contributions) and local government. A series of regression models to predict different highway expenditures as a function of utilization, capacity, and funding shares are estimated. We find that there is a share of expenditures by each level of government which results in a minimum expenditure for each funding category (capital, operating). That minimum is not very far from typical state/local mixes found in many states. The results of this study can be applied in formulation of efficient network financing arrangements. Policies can be formulated that can help adjust the financial responsibilities of transportation networks between government layers. Transportation Research Record: Journal of the Transportation Research Board 1812 27-36. [bib] [presentation]
- Levinson, David (2002)
Identifying Winners and Losers in Transportation
Abstract: This paper explores the issues surrounding transportation equity for effects both external and internal to transportation. Several examples of transportation "improvements" imposing transportation costs on more individuals than who are benefited are provided. Beyond counting the number of winners and losers, several quantitative measures of equity are suggested. To that end, transportation benefit cost analyses should include an "Equity Impact Statement". This statement would consider the distribution of the opportunities to participate in decisions and the outcomes of those decisions (in terms of mobility, economic, environmental, and health effects) that different strata (spatial, temporal, modal, generational, gender, racial, cultural, and income) of the population receive. Policy makers would then have additional information on which to base decisions.
Keywords: Environmental Justice, Social and Economic Factors, Equity, Benefit-Cost, Transportation Evaluation. Transportation Research Record: Journal of the Transportation Research Board 1812 179-185. [bib] [presentation] - Levinson, David and Seshasai Kanchi (2002)
Road Capacity and the Allocation of Time
Abstract: Additional highway capacity, by increasing travel speed, affects the individual share of time within a 24-hour budget allocated to various activities (time spent at and traveling to home, shop, work and other). Some activities will be undertaken more, others less. This paper extends previous research that identified and quantified induced demand in terms of vehicle miles traveled, by considering what type of demand is induced and which activities are consequently reduced, using the 1990 and 1995 Nationwide Personal Transportation Survey and Federal Highway Administration highway statistics data. While total travel times have not seen any significant change between the years 1990 and 1995, there is a significant change in activity durations. Further, as a result of additional capacity, workers spend less time traveling. Workers also spend more time at home and other activities and less at work and shop. Non-workers, in contrast, travel more, and spend more time shopping and at home, but less time at other activities. This points out the differences in discretionary and non-discretionary activities for workers and non-workers. It also suggests that there are real gains from capacity in people's lives, at least in the short term, as it is time, and not VMT, that individuals base decisions on.
Keywords: Time Use, Travel Behavior, Activity Patterns, Roadway Capacity, Induced Demand., Journal of Transportation and Statistics 5(1) pp 25-46. [bib] [presentation] - Levinson, David, Seshasai Kanchi, and David Gillen (2002)
Inter-technology Effects in Intelligent Transportation Systems
Abstract: This project examines the expected benefits of varying combinations of ITS applications: Freeway Service Patrol, Changeable Message Signs, and Ramp Metering. The research analyzes the simulated results of a stylized network in a microscopic traffic simulator. The traffic network includes parallel roadways, ramp meters and changeable message signs. We have tested these technologies in various combinations. We measure effectiveness as consumers' surplus and define a measure of inter-technology economies. In brief, it is found that additional technologies are sub-additive, and more benefits come from each technology in isolation than when it is bundled with other technologies.
Keywords: Transportation System Management, Inter-technology Economies, Freeway Service Patrol, Changeable Message Signs, Ramp Metering, Intelligent Transportation Systems, Evaluation, Transportation Research Record: Journal of the Transportation Research Board 1800 1-5. [bib] [presentation] - Levinson, David (2002)
The Economics of Traveler Information from Probes
Abstract: This paper examines the economics of traveler information from probe vehicles to understand how many probes are needed to provide useful information, and how that probe information might be supplied to travelers. Probes differ from permanently installed roadway detection devices both because they provide information that is less current and because an information system centered on this technology can be organized in the form of private clubs rather than a government agency. This paper estimates travel time associated with various shares of probes among the fleet by simulating different levels of probes, information subscription, and congestion. It examines the travel time savings under both recurring and non-recurring congestion. When there is non-recurring congestion, a low frequency of probes is sufficient to detect the incident and enable information consumers to choose alternates. However, smoothing the stochastic nature of traffic under recurring congestion requires a relatively high share of probes (up to one-third of the fleet), depending on the level of congestion.
Keywords: Transportation Information Systems, In-Vehicle Navigation, Advanced Traveler Information Systems, Probes, En Route Guidance Public Works Management and Policy 6(4) pp 241-250 (April). [doi] [bib] - Levinson, David (2001) Why States Toll: An Empirical Model of Finance Choice Abstract: This paper examines the question of why some states impose tolls while others rely more heavily on gas and other taxes. A model to predict the share of street and highway revenue from tolls is estimated as a function of the share of non-resident workers, the policies of neighboring states, historical factors, and population. The more non-resident workers, the greater the likelihood of tolling, after controlling for the miles of toll road planned or constructed before the 1956 Interstate Act. Similarly if a state exports a number of residents to work out-of-state and those neighboring states toll, it will be more likely to retaliate by imposing its own tolls than if those states don't. The policy implications for the future of congestion pricing are clear, if hard to implement. Decentralization of finance and control of the road network from the federal to the state, metropolitan and city and county levels of government will increase the incentives for the highway-managing jurisdiction to impose tolls. And tolls are a necessary prerequisite for an economically efficient strategy of congestion pricing. Journal of Transport Economics and Policy 35(2) 223-238 (May). [bib] [presentation]
- Levinson, David (2001) Financing Infrastructure Over Time Abstract: A model to examine the choice by jurisdiction whether to finance roads with taxes or tolls is developed. The idea of decentralized, local control and multiple jurisdictions distinguishes this analysis from one where a central authority maximizes global welfare. Key factors posited to explain the choice include the length of trips using the roads, the size of the governing jurisdiction, the elasticity of demand to revenue instruments, and the transaction costs of collection - which dictate the size and scope of the free rider problem associated with financing. Spatial complexity in this problem results from the fact that jurisdiction residents use both local and non-local networks, and each jurisdiction's network is used by both local and non-local residents. The central thesis argues that, since jurisdictions try to do well by their residents who are both voters and travelers, the effects of a revenue instrument on local residents is a key consideration in the choice of that revenue instrument. Decentralization of control and lower toll collection costs are identified as conditions under which tolls would more likely become the preferred revenue instrument for highways. Journal of Urban Planning and Development American Society of Civil Engineers 127(4) 146-157 (Dec). [doi] [bib] [presentation]
- Levinson, David (2000) Revenue Choice on a Serial Network Abstract: A model to examine the choice by jurisdiction whether to finance roads with taxes or tolls is developed. The idea of decentralized, local control and multiple jurisdictions distinguishes this analysis from one where a central authority maximizes global welfare. Key factors posited to explain the choice include the length of trips using the roads, the size of the governing jurisdiction, the elasticity of demand to revenue instruments, and the transaction costs of collection - which dictate the size and scope of the free rider problem associated with financing. Spatial complexity in this problem results from the fact that jurisdiction residents use both local and non-local networks, and each jurisdiction's network is used by both local and non-local residents. The central thesis argues that, since jurisdictions try to do well by their residents who are both voters and travelers, the effects of a revenue instrument on local residents is a key consideration in the choice of that revenue instrument. Decentralization of control and lower toll collection costs are identified as conditions under which tolls would more likely become the preferred revenue instrument for highways.. Journal of Transport Economics and Policy 34,1: 69-98. [bib]
- Levinson, David (1999) Space, Money, Life-cycle, and the Allocation of Time Abstract: Allocation of time to various activities is known to be a function of various demographic, socio-economic, seasonal, and scheduling factors. This paper examines those variables through exploration of the 1990 Nationwide Personal Transportation Survey, which has been inverted to track activity durations. The data are examined in single and multi-variate contexts. Two key issues are considered. First, to what extent does activity duration influence travel duration after controlling for activity frequency. This is tested with a set of models explaining travel duration. The data show activity duration does have positive and significant effects on travel duration, supporting recent arguments in favor of activity based models. Second, which is a more important effect in explaining the large changes in travel and activity patterns over the past thirty years accompanied by the increase in female labor force participation, the loss of discretionary time due to work, the change in metropolitan location, or the rise in per capita income. To examine this second question more rigorously, a choice model is constructed which examines both the decision to undertake an activity and the share of time within a 24 hour budget allocated to several primary activities: home, work, shop, and other activities. The utility functions for the activities are comprised of demographic, socio-economic, temporal, and spatial factors. The data also suggest that income and location have modest effects on time allocation compared with the loss of discretionary time due to working.. Transportation 26: 141-171. [bib] [presentation]
- Gillen David and David Levinson (1999) The Full Cost of Air Travel Abstract: In this paper we review the theoretical and empirical literature on the cost structure of the provision of air transportation and specify and estimate our own cost functions. We develop a full cost model which identifies the key cost components and then we measure those costs component by component: user costs, carrier costs, infrastructure costs, time and congestion costs, noise costs, accident costs, and pollution costs. Applying the models to data for domestic air travel in the California Corridor, the total long run average cost is estimated to be $0.13 per passenger kilometer traveled. The single largest cost category is owning and operating a plane. In general, because of large fixed cost components, the average cost of infrastructure exceeds the marginal cost.. Transportation Research Record :Journal of the Transportation Research Board 1662: 1-9. [bib] [presentation]
- Levinson, David (1998)
Speed and Delay on Signalized Arterials
Abstract: This research presents a model to predict the influence of demand and capacity on the running speed of signalized arterials in Montgomery County, Maryland. The model separates the changes to link running speed due to same-direction traffic and intersection approach delay from cross traffic. It is found that flow has a small impact on link speed, each 1000 vehicles per lane per hour reduces speed by 4 - 8 kph. Longer links have higher speeds, indicating that they more closely approximate free-flow conditions. A surprising result comes from measuring the effect of an additional lane on link speed, after controlling for flow per lane. It is found that there are slight diseconomies of additional lanes in terms of speed, each additional lane is associated with somewhat slower speeds. Measures of intersection and link travel times are also compared. Although link running times exceed intersection stopped delay, total intersection delay (stopped and approach) exceeds the delay caused by same-direction traffic. This information can inform investment decisions about roadway and intersection improvements.
Keywords: volume-delay function, signal delay, approach delay, traffic flow theory, running speed, highway capacity, Montgomery County Maryland . ASCE Journal of Transportation Engineering 124: 3 258-264. [doi] [bib] - Levinson, David (1998) Accessibility and the Journey to Work Abstract: This study analyzes the effect of accessibility to jobs and houses at both the home and work ends of trips on commuting duration for respondents to a household travel survey in metropolitan Washington, DC. A model is constructed to estimate the effects of demographics and relative location on the journey to work. Analysis finds that residences in job-rich areas and workplaces in housing-rich areas are associated with shorter commutes. An implication of this study is that, by balancing accessibility, the suburbanization of jobs maintains stability in commuting durations despite rising congestion, increasing trip lengths, and increased work and non-work trip making.. Journal of Transport Geography 6:1 11-21. [bib]
- Levinson, David, David Gillen, and Adib Kanafani (1998) A Comparison of the Social Costs of Air and Highway Abstract: This paper provides a comprehensive survey of the literature on the measures of social costs, providing an indication of the state of engineering and economic literature. We operationalize the new thinking about which externalities seem appropriate to consider in an analysis of the transportation system. We construct measures of each externality: noise, air pollution, accidents, and congestion for the highway and air transportation modes, where possible as a function of the amount of output or use, rather than as simple unit costs. We find that noise is the dominant cost of air travel, followed by congestion, air pollution and accidents. For highway travel, accidents are the most significant cost, followed by congestion, noise, and air pollution. The social costs of highway travel are about 15% of the full cost of a highway trip, while the smaller social costs of air travel are only 5% of the full cost of an air trip. A highway trip generates four to five times as much externality as an air trip.. Transport Reviews 18:3 215-240. [bib] [presentation]
- Levinson, David (1997) The Limits to Growth Management Abstract: This paper reviews and critiques the growth management system in Montgomery County, Maryland with the intent of finding generalizable lessons. An overview of the twenty year old system is followed by an analysis of its consequences and implications. The system fails to provide effective price signals, rather relying on proactive command and control policies from the county government. Moreover the system fails to raise sufficient revenue for new infrastructure. The paper suggests that an alternative, reactive, approach, which links the threads of infrastructure financing and adequate public facilities by replacing quotas with a market based approach of cost-based prices, would be more equitable, efficient, and effective in implementing county goals.. Environment and Planning b: Planning and Design 24: 689-707. [bib] [presentation]
- Levinson, David, Jean-Michel Mathieu, Adib Kanafani, and David Gillen (1997) The Full Cost of High-Speed Rail: An Engineering Approach Abstract: This paper examines the full costs, defined as the sum of private and social costs, of a high speed rail system proposed for a corridor connecting Los Angeles and San Francisco in California. The full costs include infrastructure, fleet capital and operating expenses, the time users spend on the system, and the social costs of externalities, such as noise, pollution, and accidents. Comparing these full costs to those of other competing modes contributes to the evaluation of the feasibility of high speed rail in the corridor. The paper concludes that high speed rail is significantly more costly than expanding existing air service, and marginally more expensive than auto travel. This suggests that high speed rail is better positioned to serve shorter distance markets where it competes with auto travel than longer distance markets where it substitutes for air.. Annals of Regional Science 31:2 189-215. [bib]
- Levinson, David, and David Gillen (1997) The Full Cost of Intercity Highway Transportation Abstract: In this paper we review the theoretical and empirical literature on the cost structure of the provision of intercity highway transportation and specify and estimate our own cost functions . We develop a full cost model which identifies the key cost components and then estimate costs component by component: user costs, infrastructure costs, time and congestion costs, noise costs, accident costs, and pollution costs. The total long run average cost is $0.34 per vehicle kilometer traveled. The single largest cost category is freeflow travel time. While the marginal cost of infrastructure is higher than its average cost, indicating that new construction is increasingly expensive, the marginal cost of driving (user fixed and variable costs) is less than the average cost, indicating that by increasing travel the user can spread his fixed cost of a vehicle over more trips without penalty.. Transportation Research -D 3:4 207-223. [bib] [presentation]
- Levinson, David and Yuanlin Huang(1997)
A Windowed Transportation Planning Model
Abstract: This research develops and applies a transportation planning model that integrates regional and local area forecasting approaches. While regional models have the scope to model the interaction of demand and congestion, they lack the spatial detail of a local approach. Local approaches typically do not consider the feedback between new project traffic and existing levels of traffic. Using a window, which retains the regional trip distribution information and the consistency between travel demand and congestion, allows the use of a complete transportation network and block level traffic zones while retaining computational feasibility. By combining the two methods, a number of important policy issues can be addressed, including the implications of traffic calming, changes in flow due to alternative traffic operation schemes, the influence of micro-scale zoning changes on nearby intersections, the impact of TDM on traffic congestion, and the consequences of a suburban light rail line.
Keywords: transportation planning model, traffic impact study, travel demand model, intersection control, window. Transportation Research Record #1607: 45-54. [bib] - Levinson, David (1997)
Job and Housing Tenure and the Journey to Work
Abstract: Tenure at jobs and houses, along with commuting patterns between home and work were studied for residents of metropolitan Washington. Two alternative potential outcomes were considered: (1) Because moving or switching jobs can be used as an opportunity to reduce commuting duration in an era of rising congestion, those who recently moved or changed jobs should have shorter than average commutes; and (2) Because most new residential construction is at the urban fringe, an area of longer commutes, those who recently moved to new homes should have longer commutes. Evaluation of the effect of commuting duration on job and housing tenure suggests that those who move on average maintain commute duration rather than having a major increase or decrease. This corroborates the idea that there are offsetting factors, where increases in commute lengths due to suburbanizing residences are counteracted by the correlated process of suburbanizing jobs..
Annals of Regional Science 31:451-471. [bib] [presentation]
originally presented at Western Regional Science Association Meeting as part of Location, Relocation, and Journey to Work, San Diego, CA, February 1995. - winner of the Charles Tiebout Prize for Best Student Paper
- Levinson, David and Ajay Kumar (1997). Density and the Journey to Work Abstract: This paper evaluates the influence of residential density on commuting behavior across U.S. cities while controlling for available opportunities, the technology of transportation infrastructure, and individual socio-economic and demographic characteristics. The measures of metropolitan and local density are addressed separately. We suggest that metropolitan residential density serves principally as a surrogate for city size. We argue that markets react to high interaction costs found in large cities by raising density rather than density being a cause of those high costs. Local residential density measures relative location (accessibility) within the metropolitan region as well as indexing the level of congestion. We conduct regressions to predict commuting time, speed, and distance by mode of travel on a cross-section of individuals nationally and city by city. The results indicate that residential density in the area around the tripmaker's home is an important factor: the higher the density the lower the speed and the shorter the distance. However, density's effect on travel time is ambiguous, speed and distance are off-setting effects on time. The paper suggests a threshold density at which the decrease in distance is overtaken by the congestion effects, resulting in a residential density between 7,500 and 10,000 persons per square mile (neither the highest nor lowest) with the shortest duration auto commutes. . Growth and Change 28:2 147-172. [bib]