Transportation networks

Transportation networks

86 Recent Doctoral Dissertations be considered an effective tool of urban growth management, multi-modal transportation systems operations, traffic ...

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86

Recent Doctoral Dissertations

be considered an effective tool of urban growth management, multi-modal transportation systems operations, traffic engineering, and as a workable mechanisms of fiscal value capture. Conversely, joint development will not as such reestablish the traditional central business district as the dominant economic center of the metropolitan area, but rather it will contribute toward a balanced urban region, where economic activities are focused on highintensity urban nodes served by rapid transit stations and other required urban transportation facilities. The systematic evaluation of determinants of success and identification of underlying reasons therefore represent a significant contribution to urban science in general, and to comprehensive transportation planning in particular.

Land economic impact of fiied guideway rapid transit systems on urban development in selected metropolitan areas: The issue of the price-distance gradients. Alterkawi, Mezyad. Texas A&A4 University, 1991. 130 pp. Chair: Wolfgang G. Roeseler . Order Number DA9133904 This research investigates and evaluates the impact of rapid-transit systems on land values in the vicinity of transit stations in large metropolitan areas. The data are based on ad valorem tax assessment before and after implementation of rapid transit systems. Review of pertinent literature, including literature on joint development projects, indicates that no study has examined the direct impact of transit systems on land values. Five North American fixed guideway rapid-transit stations were selected for detailed study. Four were in the METRO Rosslyn Corridor in Arlington, Virginia. The fifth was in Atlanta, Georgia. The Bay Area Rapid Transit system in San Francisco, and the Toronto Metro system in Canada were also examined using previous data. A comprehensive evaluation of the impact of these systems on land values near selected stations was undertaken. The research-evaluation methodology introduced in a similar study by Hoyt (1933) was used in this study. Findings from this study indicate that fixedguideway, rapid-transit systems have a strong positive impact on land values. Factors other than transit facilities, however, contribute to the increase of property values near the stations. A statistical model using regression techniques was devised to show the pattern of land-value changes near fixed-guideway, rapid-transit stations. Price flexibility of distance E,~ concept was also used to measure the percentage change in the price of land with respect to change in land distance from a development area.

Visions of urban freeways, 1930-1970. Ellis, Clifford Donald. University of California, Berkeley, 1990.463 pp. Order Number DA9126544

This dissertation explores the evolution of freeway planning ideas for American central cities between 1930 and 1970. Highway engineers, city planners, architects, landscape architects and special interest groups held different images of the existing city, the city of the future, and the place of limited-access, high-capacity highways in the emerging urban context. The study examines these theories and argues that they structured freeway planning policy and practice. The research concentrates on the ideas of the directly involved design professionals. Highway engineers and transportation planners embraced theories and methodologies that emphasized serving traffic demand. These ideas left little room for a qualitative concern with urban life and form; trafficmoving efficiency overruled other variables. City planners, fragmented into separate factions, could not agree on a theory of good city form, and offered few persuasive alternatives to the freeway ‘solution’ to urban transportation problems. Architects, who often held strong ideal images for urban freeways, were excluded from the planning process until the late 196Os, too late to have a major influence. Landscape architects pioneered in parkway design during the 1920s and 193Os, but their influence on freeway planning waned thereafter, regaining strength only after the freeway revolts of the 1960s. The original designers of America’s urban freeways tried to portray freeway planning as an apolitical, technical process. It proved to be politically explosive, value-laden and fraught with aesthetic and social dimensions. Planning, engineering and design professionals need to reflect more on the ideas and images that inform their prescriptions for cities. Professional world views and values powerfully shape their work, including the technical analysis conventionally believed to determine plans.

TRANSPORTATION

NETWORKS

Comparative analysis of alternative simultaneous transportation network equilibrium models. Hasan, Mohamad Kamal El-Den Ahmad. Texas A&A4 University, 1991. 186 pp. Chair: Nabil Safwat. Order Number DA9206506 Existing transport planning methodologies which have been applied to hundreds of transport studies throughout the world for the past 40 years involve a sequential process for predicting short-run transport equilibria, often with four stages: trip generation, trip distribution, modal split and traffic assignment. Unfortunately, the sequential approach has an inherent weakness; its predictions need not be internally consistent. This deficiency has motivated attempts to predict all four stages simultaneously. Research intended to develop integrated models and related computational procedures for predicting short-run

Recent Doctoral Dissertations transport equilibria has proceeded in three directions. One line of investigation, the Equivalent Optimization approach, has significant computational advantages; the others, the Variational Inequality and Stochastic Equilibrium approaches, permit richer modeling of user behavior. A critical review of previous studies of transportation network equilibrium models illustrates the trade-offs between behavioral and computational aspects of the transport equilibrium problem. In this dissertation, we address these trade-offs by performing a formal comparison between the variational inequality, equivalent optimization and traditional sequential approaches to the problem. To have a consistent comparison between the equivalent optimization approach and the variational inequality approach, a Generalized Simultaneous Transportation Equilibrium Model (GSTEM) has been developed. This model explicitly combines trip generation, trip distribution, modal split and traffic assignment for a general class of behaviorally sound demand models, and general asymmetric cost functions. The GSTEM is a generalization of the Simultaneous Transportation Equilibrium Model (STEM) which was developed by Safwat and Magnanti (1988) and which can be cast as an Equivalent Convex Program (ECP). The GSTEM cannot be cast as an ECP, but as a Variational Inequality (VI). A relaxation algorithm has been developed to solve this VI. Implementation programs for comparative analysis of computational and behavioral issues have been developed for the Tyler, Texas urban transportation network. The main findings of this dissertation are: (i) The simultaneous approach to travel demand forecasting can consistently produce better traffic flow predictions compared with the existing conventional sequential approach currently used in practice, at essentially no additional computational cost. In the case of Tyler, Texas, the relative improvements were between 9%-43% with an average of 25%. (ii) The equivalent optimization approach, in addition to offering significant computational advantages compared with the variational inequality approach, is behaviorally not as restrictive as was previously thought. That is, the additional efforts to include link interaction may not be strongly justified in practice, and hence the equivalent optimization approach (e.g. STEM) represents a reasonable practical compromise between computational and behavioral considerations of the problem. Based on these findings, further use and application of the simultaneous approach (particularly the equivalent optimization models) to other urban transport studies throughout the world is strongly recommended.

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The urban areas, competition for road space at junctions is one of the major causes of congestion and accidents. Routes chosen to avoid conflict at junctions have a mutually beneficial effect that should improve circulation and reduce accidents. A prototype design tool has been developed to provide for traffic management based on such routes. The mathematical model behind the design tool works with a given road network and a given Origin-Destination (O-D) demand matrix to produce feasible routes for all drivers in such a way that the weighted sum of potential conflicts is minimized. The result is a route selection in which all journeys from origin i to destination j follow the same route. The method that works best splits the problem into single commodity problems and solves these repeatedly by the Out-ofKilter algorithm. Good locally optimal solutions can be produced by this method, even though global optimality cannot be guaranteed. Software for a microcomputer presented here as part of the design tool is capable of solving problems on realistic networks in a reasonable time. This method is embedded in a suite of computer programming which makes the input and output straightforward. Used as a design tool in the early stages of network design, it gives a network-wide view of the possibilities for reducing conflict and indicates a coherent set of traffic management measures. The ideal measure would be automatic route guidance, such as the pilot scheme currently being developed for London. Other measures include a set of one-way streets and banned turns. The resulting turning flows could be used as input to the signal optimizer TRANSYT to determine signal settings favoring the routing pattern.

Incentive-compatible capacity pricing for congested transportation facilities: A gametheoretic approach. Hong, Sungwook. University of Pennsylvania, 1991. 258 pp. Supervisor: Patrick T. Harker. Order Number DA9200346

The central focus of this dissertation is to investigate the theory and application of market-driven models for the management of congested transportation network facilities. Computable Nash and generalized Nash equilibrium models are used to estimate the value to users of using facilities, with a view to using this information for market pricing. Variational inequality and quasi-variational inequality formulations are used to solve the oligopolistic transport market models. These game-theoretic models are then used to develop a market mechanism for determining capacity allocation and price. Different users are being offered widely varying prices based on their The development of a mathematical program- valuation of basically the same transport service. The ming technique as a design tool for traffic man- quality attributes of the transportation service are agement. Wackrill, Patricia Anne. Council for Na- differentiated to allow users with different prefertional Academic Awards (United Kingdom), 1990. ences to select different qualities. Two applications are included. In the first application, passenger air 267 pp. trip deOrder NumberBRDX91975 travel, given the total origin-destination

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Recent Doctoral Dissertations

mand, airport capacity and cost of each flight, the model derives the flight patterns, ticket prices, routes and carrier choice for passengers and landing priorities. The choice of travellers between competing airlines is represented by a logit model. Two models are proposed for pricing of landing slots for airlines: the first includes an exogenously determined landing/ takeoff slot allocation, and the second includes an endogenous allocation of slots that depends on the value of the slot to each airline. In the second application, we present a computable equilibrium model of an internal market for track resources in a railroad. The problem of estimating the value to each train of track capacity, which in turn is used to create the actual train schedules, is formulated as an Nplayer, noncooperative game with nondisjoint strategy sets. In order to incorporate the effects of other traffic on a given train schedule (the mean and variance of total travel time), a new delay model for a scheduled railroad on a partially double track rail line is developed. Using this model, a game-theoretic model is developed in which each train tries to maximize its utility (defined as minimizing the deviations from their ideal schedules); the generalized Nash equilibrium for this model is found as a solution to a quasi-variational inequality problem. Finally, we formulate a nonlinear programming model in which one agent controls all train movements. This latter model is used in order to “benchmark” and judge how close the price from the market pricing system (the game-theoretic model) comes to the optimal prices. Data from a Class I railroad are used to illustrate the practical use of the model.

Modeiiing dynamic stochastic user equilibrium for urban road networks. Vythoulkas, Petros C. Crarlfield Institute of Technology (United Kingdom), 1991.231 pp. Supervisor: Ian G. Black. OrderNumber BRDX94612 In this study, a dynamic assignment model is developed that estimates travellers’ route and departure time choices, and the resulting time varying traffic patterns during the morning peak. The distinctive feature of the model is that it does not restrict the geometry of the network to specific forms. The proposed framework of analysis consists of a travel time model, a demand model and a demand adjustment mechanism. Two travel time models are proposed. The first is based on elementary relationships from traffic flow theory and provides the framework for a macroscopic simulation model which calculates the time varying flow patterns and link travel times given the time dependent departure rate distributions; the second is based.on queuing theory and models roads as bottlenecks through which traffic flow is either uncongested or fixed at a capacity independent of traffic density. Travellers’ choices are assumed to result from the trade-off between travel time and schedule delay, and each individual is assumed to

first choose a departure time t, and then select a reasonable route, conditional on the choice oft. The demand model therefore has the form of a nested logit. The model outputs exhibit the characteristics of real world traffic patterns observed during the peak, i.e. time varying flow patterns and travel times that result from time varying departure rates from the origins. It is shown that increasing the work start time flexibility results in a spread of the departure rate distributions over a longer period, and therefore reduces the level of congestion in the network. Furthermore, it was shown that increasing the total demand using the road network results in higher levels of congestion, and that travellers tend to depart earlier in an attempt to compensate for the increase in travel times. Moreover, experiments using the queuing theory based travel time model have shown that increasing the capacity of a bottleneck may cause congestion to develop downstream, which in turn may result in an increase of the average travel time for certain Origin-Destination (O-D) pairs. The dynamic assignment model is also applied to estimate the effects that different road pricing policies may have on trip choices and the level of congestion; the model is used to demonstrate the development of the shifting peak phenomenon.

Spatial variability of travel time coefficients in travel demand models and its implication for transportation equilibrium. Jung, Sungyong. The Ohio State University, 1991. 186 pp. Adviser: Philip A. Viton.

OrderNumberDA9211158 The dissertation presents the spatial logit model using the expansion method as a way of introducing space into the context of the standard logit model. The empirical result of the model supports the spatial variability of travel time values. The findings in the spatial logit model are incorporated in a spatial equilibrium model for an urban area. From the results of the equilibrium model, we conclude that the equilibrium conditions will vary significantly over an urban space as long as there is taste variation over that space. Detailed policy simulations and sensitivity analyses are also conducted.

TRAVELBEHAVIOR

The development of a procedure to forecast traffic volumes on urban segments of the state and interstate highway systems. (Volumes I and II). Saha, Sunil Kumar. Purdue University, 1990. 699 pp. Major Professor: Jon D. Fricker. Order Number DA9116453 This study has developed a simplified traffic forecasting procedure for the highly traveled interstate