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Dr. David M. Levinson

Persistent link for this collectionhttps://hdl.handle.net/11299/179806

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Browsing Dr. David M. Levinson by Issue Date

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    Specifying, Estimating and Validating a New Trip Generation Model: Case Study in Montgomery County, Maryland
    (Transportation Research Board, 1994) Kumar, Ajay; Levinson, David M
    This paper discusses the development of an afternoon peak period trip generation model for both work and non-work trips. Three data sources are used in model development, a Household Travel Survey, a Census-Update Survey, and a Trip Generation Study. Seven one-direction trip purposes are defined, specifically accounting for stops made on the return trip from work to home. Trips are classified by origin and destination activities rather than by production and attraction, so reframing the conventional schema of home-based and non-home-based trips. Prior to estimating the model, the Household Travel Survey was demographically calibrated against the Census-Update to minimize demographic bias. A model of home-end trip generation is estimated using the Household Travel Survey as a cross-classification of the demographic factors of age and household size in addition to dwelling type. Non-home-end generation uses employment by type and population. The model was validated by comparison with a site based Trip Generation Study, which revealed an under-reporting of the relatively short and less regular shopping trips. Normalization procedures are developed to ensure that all ends of a chained trip were properly accounted for.
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    Integrating Feedback into the Transportation Planning Model
    (Transportation Research Board, 1994) Levinson, David M
    This research develops and applies a new structure for the transportation planning model that includes feedback between demand, assignment, and traffic control. New methods, combined with a renewed interest in transportation planning models prompted by the Clean Air Act of 1990 and the Intermodal Surface Transportation Efficiency Act of 1991, warrant a reconsideration of the traditional "four-step" transportation planning model. This paper presents an algorithm for feedback which results in consistent travel times as input to travel demand and output from route assignment. The model, including six stages of Trip Generation, Destination Choice, Mode Choice, Departure Time Choice, Route Assignment and Intersection Control is briefly outlined. This is followed by an application comparing a base year 1990 application with a forecast year of 2010. The 2010 forecast is solved both with and without feedback for comparison purposes. Incorporation of feedback gives significantly different results than the standard model.
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    The Rational Locator: Why Travel Times Have Remained Stable
    (American Planning Association, 1994) Levinson, David M; Kumar, Ajay
    This paper evaluates household travel surveys for the Washington metropolitan region conducted in 1968 and 1988, and shows that commuting times remain stable or decline over the twenty year period despite an increase in average travel distance, after controlling for trip purpose and mode of travel. The average automobile work-to-home time of 32.5 minutes in both 1968 and 1988 is, moreover, very consistent with a 1957 survey showing an average time of 33.5 minutes in metropolitan Washington. Average trip speeds increased by more than 20 percent, countering the effect of increased travel distance. This change was observed during a period of rapid suburban growth in the region. With the changing distributional composition of trip origins and destinations, overall travel times have remained relatively constant. The hypothesis that jobs and housing mutually co-locate to optimize travel times is lent further support by these data.
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    Operational Evidence of Changing Travel Patterns
    (Institute of Transportation Engineers, 1994) Levinson, David M; Kumar, Ajay
    This paper utilizes a traffic counts database covering a ten year period (1976-1985) to identify travel trends for Montgomery County, a suburb of Washington D.C. Generally, travel behavior is analyzed using person based travel survey data. The use of traffic counts to understand travel behavior is a relatively new approach. Unlike household surveys, which are typically characterized by respondent and sample bias, and require special effort for their collection, traffic counts are routinely collected by Departments of Transportation and provide the best available measure of observed traffic volumes. The study provides fresh evidence to support some of the earlier findings: an increase in lateral commuting as a share of travel, changes in work and non-work trip proportions, and increase in peak spreading. An interesting result in this paper relates to a more pronounced directionality in radial as compared with lateral trips. The relative symmetry of traffic flows along lateral routes compared with radial routes results in better utilization of the suburban road network. Non-work trips emerge as the more elastic trips, shifting to off-peak hours with an increase in congestion.
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    Temporal Variations on the Allocation of Time
    (Transportation Research Board, 1995) Levinson, David M; Kumar, Ajay
    This study investigates the allocation of time and trip-making across time-of-day, day-of-week, and month-of-year, as well as over the past forty years. Some interesting findings result. People are working much more, shopping somewhat more on weekends, and stay at home less today than forty years ago. Time spent in travel on each weekend day (Saturday or Sunday) exceeds that on any weekday, as it did forty years ago. Time spent shopping on a typical day in the busiest month (December) is more than double that in the least busy month (September). Monthly variations in daily time in travel exceed 10 percent. The time of day patterns of shop and other trips for workers and nonworkers are both rational: nonworkers peak in mid-day away from rush hour while workers peak just after work, indicating trip chaining.
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    A Multi-modal Trip Distribution Model
    (Transportation Research Board, 1995) Levinson, David M; Kumar, Ajay
    This paper presents a multimodal trip distribution function estimated and validated for the metropolitan Washington region. In addition, a methodology for measuring accessibility, which is used as a measure of effectiveness for networks, using the impedance curves in the distribution model is described. This methodology is applied at the strategic planning level to alternative HOV alignments to select alignments for further study and Right-of-Way preservation.
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    An Evolutionary Transportation Planning Model: Structure and Application
    (Transportation Research Board, 1995) Levinson, David M
    This paper describes an evolutionary transportation planning model wherein the demand in a given year depends on the demand of the previous year. The model redistributes a fraction of the work trips each year due to the relocation of a household or taking a new job, while changes in distribution due to growth (or decline) are considered. This hybrid-evolutionary model is compared with an equilibrium model, wherein supply and demand are solved simultaneously. The reasons for preferring the evolutionary method to the equilibrium approach are several: (a) the ability to more easily use observed data and thereby limit modeling to changes in behavior; (b) additional realism in the concept of the model; (c) the provision of a framework for extension to integration with land use models; and (d) the additional information available to policy makers.
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    Activity, Travel, and the Allocation of Time
    (American Planning Association, 1995) Levinson, David M
    This paper analyzes 1968 and 1987-88 metropolitan Washington, DC household travel surveys to understand the daily allocation of time among different activities of individuals classified by work status and gender. The increase in female labor force participation rates has produced an increase in overall time spent at work per person. The increase in work trips and the simultaneous increase in nonwork trips has resulted in less time spent at home. People are substituting money for time spent at home, buying household services outside the home. The group of individuals who work at home is analyzed separately to obtain an understanding of this growing segment.
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    Chained Trips in Montgomery County, Maryland
    (Institute of Transportation Engineers, 1995-05) Kumar, Ajay; Levinson, David M
    This paper analyzes the 1987-88 Metropolitan Washington Council of Governments home interview survey to understand how work trips are combined into trip chains and to relate trip chaining with demographic and travel characteristics. The focus is on the work trips during the morning and afternoon peak period and the stops made on the way for performing nonwork activities. The work trips during the afternoon period are much more likely to involve trip chaining as compared to the morning period. Women are more likely to link work trips with other activities as compared to men. Stops are closer to home than work.
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    Home or Office:Technology, Attitude, and At-Home Work
    (1996) Levinson, David M
    This paper examines the influence of technology and employer attitude on the decision to work at home. Using data from a suburban Washington household travel survey, it is found that both technology and a favorable employer attitude are positively associated with the number of hours and days in a two week period during which a respondent works at home. Other factors, including demographics, socio-economics, commuting time, and employer type were not statistically significant. Log-linear and translog forms were better fits than a simpler linear form.
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    Density and the Journey to Work
    (Center for Business and Economic Research, University of Kentucky. Published by Blackwell Publishers, 1997) Levinson, David M; Kumar, Ajay
    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.
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    A Windowed Transportation Planning Model
    (Transportation Research Board, 1997) Levinson, David M; Huang, Yuanlin
    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.
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    Job and Housing Tenure and the Journey to Work
    (Springer-Verlag, 1997) Levinson, David M
    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.
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    The Full Cost of High-Speed Rail: An Engineering Approach.
    (Springer-Verlag, 1997) Levinson, David M; Mathieu, Jean-Michel; Kanafani, Adib; Gillen, David M
    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.
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    The Limits to Growth Management
    (Pion, 1997) Levinson, David M
    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.
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    Speed and Delay on Signalized Arterials
    (American Society of Civil Engineers, 1998) Levinson, David M
    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.
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    The social costs of intercity transportation: a review and comparison of air and highway
    (Taylor & Francis, Ltd, 1998) Levinson, David M; Gillen, David; Kanafani, Adib
    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 percent of the full cost of a highway trip, while the smaller social costs of air travel are only 5 percent of the full cost of an air trip. A highway trip generates four to five times as much externality as an air trip.
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    Accessibility and the Journey to Work
    (Pergamon, 1998) Levinson, David M
    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.
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    The Full Cost of Intercity Highway Transportation
    (Pergamon, 1998) Levinson, David M; Gillen, David
    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.
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    Tolling at a Frontier: A Game Theoretic Analysis
    (Elsevier Science Publishing Company, Incorporated, 1999) Levinson, David M
    Frontiers provide an opportunity for one jurisdiction to remedy inequities (and even exploit them) in highway finance by employing toll-booths, and thereby ensuring the highest possible share of revenue from non-residents. If one jurisdiction sets policy in a vacuum, it is clearly advantageous to impose as high a toll on non-residents as can be supported. However, the neighboring jurisdiction can set policy in response. This establishes the potential for a classical prisoner's dilemma consideration: in this case to tax (cooperate) or to toll (defect). Even if both jurisdictions would together raise as much revenue from taxes as from tolls (and perhaps more since taxes may have lower collection costs), the equilibrium solution in game theory, under a one-shot game, is for both parties to toll. However in the case of a repeated game, cooperation (taxes and possibly revenue sharing) which has lower collection costs is stable.