Scheduling considerations for a branching transit route

This paper addresses the impacts of different scheduling alternatives for a branching transit route. It examines different schedule alternatives that might be used to optimize the route performance in terms of the passenger traveling time distributed among branch passengers and trunk‐line passengers. The schedule alternatives considered include transit vehicle allocation to different branches, offset shifting across vehicles on different branches, and vehicle holding (slack time) in the transit vehicle schedule. With these variables, several vehicle schedules are devised and examined based on a wide variety of possible passenger boarding scenarios using deterministic service models. Test outcomes provide general conclusions about the performance of the strategies. Vehicle assignment leading to even headways among branches is generally preferred for the case of low passenger demand. However, when passenger demand is high, or the differences between the passenger demands on branches are significant, unequal vehicle assignment will be helpful to improve the overall route performance. Holding, as a proactive strategy in scheduling, has the potential to be embedded into the schedule as a type of slack time, but needs further evidence and study to determine the full set of conditions where it may be beneficial. Offset shifting does not show sufficient evidence to be an efficient strategy to improve route performance in the case of low or high passenger demand.     

Automated transit headway control via adaptive signal priority

This paper reports on a study that developed a next‐generation Transit Signal Priority (TSP) strategy, Adaptive TSP, that controls adaptively transit operations of high frequency routes using traffic signals, thus automating the operations control task and relieving transit agencies of this burden. The underlying algorithm is based on Reinforcement Learning (RL), an emerging Artificial Intelligence method. The developed RL agent is responsible for determining the best duration of each signal phase such that transit vehicles can recover to the scheduled headway taking into consideration practical phase length constraints. A case study was carried out by employing the microscopic traffic simulation software Paramics to simulate transit and traffic operations at one signalized intersection along the King Streetcar route in downtown Toronto. The results show that the control policy learned by the agent could effectively reduce the transit headway deviation and causes smaller disruption to cross street traffic compared with the existing unconditional transit signal priority algorithm.     

Practical safety considerations for short headway automated transit systems

Continued interest in Personal Rapid Transit (PRT) systems as one solution to urban traffic congestion emphasizes the need for careful consideration of the safety of short headway automated transit systems. Current approaches to the determination of safe headways are reviewed. The reduction in headway which could be achieved by improved braking and signaling hardware is outlined. Improved design of emergency brakes is the most important single factor in the reduction of safe headways.

Very short headway systems are reviewed from a safety standpoint. Such systems might be safely operated if operation at intermediate headways (separations on the order of the stopping distance) can be avoided.     

Schedule-based transit assignment model with vehicle capacity and seat availability

In this paper, we propose a new schedule-based equilibrium transit assignment model that differentiates the discomfort level experienced by sitting and standing passengers. The notion of seat allocation has not been considered explicitly and analytically in previous schedule-based frameworks. The model assumes that passengers use strategies when traveling from their origin to their destination. When loading a vehicle, standing on-board passengers continuing to the next station have priority to get available seats and waiting passengers are loaded on a First-Come-First-Serve (FCFS) principle. The stimulus of a standing passenger to sit increases with his/her remaining journey length and time already spent on-board. When a vehicle is full, passengers unable to board must wait for the next vehicle to arrive. The equilibrium conditions can be stated as a variational inequality involving a vector-valued function of expected strategy costs. To find a solution, we adopt the method of successive averages (MSA) that generates strategies during each iteration by solving a dynamic program. Numerical results are also reported to show the effects of our model on the travel strategies and departure time choices of passengers.     

Queue-dependent vehicle dispatching with options and optimal fleet size

A queue-dependent vehicle dispatching rule, with options to use special vehicles (rented, reserve, shared etc.) for relieving long waiting lines, is considered. The transportation system under consideration has one source terminal and a fleet of N regular vehicles. Passengers are assumed to arrive individually at the source terminal according to a Poisson process. An efficient recursive algorithm is derived to analyse the performance of the system. An average cost criterion is used to determine the firm's fleet size and dispatching strategy for a simpler system. This is a variant of a “Random vehicle dispatching with options” rule proposed by Zuckerman and Tapiero (1980).     

Random vehicle dispatching with options and optimal fleet size

A dispatching problem with random availability of vehicles and options to send rented vehicles is considered. We assume passenger arrivals to be described by a pure-birth process. Such a problem is analytically attractive and is shown to have practical applications in vehicle dispatching models. An average cost criterion is used to determine firm's fleet size and option (renting) strategy.     

Developing link-based particle number emission models for diesel transit buses using engine and vehicle parameters

To better assess health impacts from diesel transportation sources, particle number emissions can be modeled on a road network using traffic operating parameters. In this work, real-time particle number emissions rates from two diesel transit buses were aggregated to the roadway link-level and modeled using engine parameters and then vehicle parameters. Modern statistical methods were used to identify appropriate predictor variables in the presence of multicollinearity, and controlled for correlated emission measurements made on the same day and testing route. Factor analysis helped to reduce the number of potential engine parameters to engine load, engine speed, and exhaust temperature. These parameters were incorporated in a linear mixed model that was shown to explain the variation attributable to link-characteristics. Vehicle specific power and speed were identified as two surrogate vehicle travel variables that can be used in the absence of engine parameters, although with a loss in predictive power compared to the engine parameter model. If vehicle speed is the only operating input available, including road grades in the model can significantly improve particle number emission estimates even for links with mild grade. Although the data used are specific to the buses tested, the approach can be applied to modeling emissions from other vehicle models with different engine types, exhaust systems, and engine retrofit technologies.     

Automated transit and land use intentions: Alternate scenarios with PRT and shuttle/loop technologies

Ecological impacts of urban sprawl on the land, as well as forces that engender sprawl are outlined. Long-range land use priorities for more compact, transit-oriented development (TOD) are seen as ecological imperatives. While Personal Rapid Transit (PRT) could solve some congestion, it does not address these priorities. Several assumptions that underlie the PRT concept, particularly the premise that denser land use is per se socially undesirable, are challenged in terms of historical precedent. Rather, the explosive scale of ubiquitous motoring is seen as the key component of today's resistance to dense development. With peripheral parking and medium-capacity AGT links to regional transportation networks, new TOD could be redefined as pedestrian-zoned and richly landscaped urban neighborhoods; this would help resolve essential traffic and environmental barriers to its realization. The simpler automated shuttle and loop technologies are seen as more compact and potentially affordable for this purpose. Steps that could help open the way toward realization of such development are discussed.     

Reducing transit fleet emissions through vehicle retrofits,replacements, and usage changes over multiple time periods

Bus transit is often promoted as a green form of transportation, but surprisingly little research has been done on how to run transit systems in a green manner. Both vehicle task assignment and purchase models are generally constructed to minimize financial costs. Integrating vehicle task assignment with purchase decisions is made challenging by the different time scales involved. An integer programming approach is used to combine vehicle purchase, retrofit and aggregated task assignment decisions. The formulation is designed to operate in sequence with traditional vehicle task assignment models, to add emissions and long term financial cost elements to the objective, while maintaining computational tractability and feasible input data requirements. In a case study, a transit agency saves money in the long term by using stimulus money to buy CNG infrastructure instead of purchasing only new buses. Carbon prices up to $400/(ton CO₂ equivalent) do not change vehicle purchase decisions, but higher carbon prices can cause more diesel hybrid purchases, at a high marginal cost. Although the motivation and numerical case study are from the US transit industry, the model is formulated to be widely applicable to green fleet management in multiple contexts.     

Learning to use transit services: adapting to unfamiliar transit travel

Transportation - Travel behavior change has become an area of interest in many cities around the world, particularly to encourage people to change from car use to transit use. Previous research...     

Express guideway transit: A case for further development in transit automation

Safe and reliable coupling and decoupling of cars from a moving train is feasible with further developments in linear motor propulsion and control of transit vehicles. This allows the last car of a train to decouple and stop at a station for a relative long dwell time, before it accelerates and is coupled to a following train. Controlled doors in front and rear of the transit vehicle permit passengers to walk through the train to the car which stops at their destination. A proposed transit system using these features is described and compared to Bombardier's Advanced Rapid Transit. Potential advantages are high schedule speed, uncrowded trains, smaller and more stations, low energy requirements and a smaller vehicle fleet.     

Polycentricity and transit service

This paper focuses on the two related issues of employment distribution and access to transit services. Using the 2001 census tract level economic activities and transit routes within the county, a number of analyses were performed to determine the location of major employment centers in Los Angeles County and how these localities may be understood within the context of a transit service operation in a polycentric metropolitan area. The identified economic subcenters contain one-third of the county employment and its firms, collectively. While these economic nodes are networked by the existing bus routes, the connection between employees and their place of work appears to be inadequate. This has created a less than optimal condition in many sections of the metropolitan area. This paper suggests methodologies for encountering this shortcoming.     

Optimal transit subsidy policy

The basic justification for transit subsidy is that such a subsidy is necessary, given substantial economies of scale, in order to permit fares to be set at a level which will result in reasonably efficient use of the service. Efficiency is not, however, merely a matter of the level of the fares but even more of the fare structure and pattern. Major changes in fare patterns are needed to permit reasonable efficiency of utilization to be attained, and full advantage derived from subsidy. Differentiation according to time and direction, as well as the distance of travel, is required. Ideally, competing modes such as the private automobile should be priced at marginal cost, differentially by time and place, and the subsidy should be derived from taxes on land values in the areas where such values are enhanced by the presence of transit service at low fares. In the absence of such conditions, fares should differ from marginal cost in ways that take into account the impacts of transit fare variations on auto traffic and congestion, and on the subsidy requirements and the adverse impacts of the taxes imposed to finance the subsidy.In addition to these economic efficiency considerations there may be added considerations of distributional impact and political acceptability, which may modify the optimal solution somewhat but should not greatly change the main outlines of the patterns to be recommended.     

Locating rapid transit lines

This paper describes the main criteria used to design rapid transit alignments. It also shows how Operational Research tools can assist the design process.     

Demand responsive transit and the integration of D/R systems with traditional transit

This paper provides a background of the development of demand-responsive transit in small communities in the U.S.A. It also backgrounds traditional transit in metropolitan areas of the United States and outlines its deficiencies in terms of today's urban sprawl and in terms of today's society in metropolitan areas. Urban sprawl has developed city-like areas around big cities, but with lower population densities. Highways and roads were built. Cars were mass-produced. These new populations have never had an alternative to the private car. Today's society includes an ever-increasing number of senior citizens and handicapped persons. Senior citizens find it difficult to get to fixed-route bus stops; handicapped persons have difficulty in boarding regular buses and wheelchair persons cannot even get on board. Particular emphasis is placed upon the examination of the development of demand-responsive transit in metropolitan Rochester, U.S.A. and a Demonstration Project, sponsored by the Urban Mass Transportation Administration of the United States Department of Transportation. The paper also examines and makes reference to the results of integrated transit in Regina, Saskatchewan, Canada. The Demonstration Project has several key objectives, the principal one of which is the integration of demand-responsive transit with the fixed-route element of traditional transit. Other important objectives of the demonstration are the balancing of peak and off-peak service so as to improve the overall utilization of resources, increase transit coverage, regular (not special) service for the elderly and the handicapped, the utilization of a computer in dispatching, digital communications, and marketing and promotional techniques.     

Energy use in personal rapid transit building and running personal rapid transit in Sweden

Travel by a Personal Rapid Transit (PRT) system may be much more energy efficient than travel by conventional road transport. The difference could be so large that the energy invested in the PRT infrastructure may be equivalent to the fuel that is saved by previous car and bus riders in less than five years. We analyzed the propulsion energy requirements of a PRT system and made a first-order calculation of the energy cost of the infrastructure and maintenance. Operation of the PRT requires only half the energy required by buses and a quarter of the energy used by passenger cars per passenger kilometer. The energy used to build the PRT infrastructure in a city may be recovered in five years if 10% of the car drivers switch to the PRT.     

Performance indicators for transit management

Transit performance can be evaluated through quantitative indicators. As the provision of efficient and effective transit service are appropriate goals to be encouraged by federal and state governments, these goals are used to develop performance indicators.Three efficiency and four effectiveness indicators are described, together with two overall indicators. These nine indicators are analyzed for comparability utilizing operating and financial data collected from public transit agencies in California.Performance indicators selected for this study should not be viewed as final. Twenty-one performance indicators proposed by previous studies were reviewed. Theoretical considerations and unavailability or unreliability of data caused omission of several useful measures like passenger-miles. Circumstances such as improved data, emphasis upon goals other than efficiency and effectiveness, and local conditions might warrant the inclusion of indicators deleted from this research.This paper is based on work conducted for the Urban Mass Transportation Administration under University Research and Training Grant CA-11-0014, Development of Performance Indicators for Transit. The views expressed herein are those of the authors and not necessarily those of the University of California or the United States Government. We are indebted to John Feren for assistance with the statistical processing and data gathering.     

Mass transit in developing cities

Using case study material, this paper examines the relative merit of metros and high performance bus systems in use in Third World cities. It demonstrates that buses with suitable priority measures are capable of meeting high passenger demands. The paper also shows that despite the poor financial performance and other shortcomings of metros, they can yield a respectable economic return. The paper draws on studies undertaken as part of the research program of the Overseas Unit of the Transport Research Laboratory.     

Calibrating a transit assignment model using smart card data in a large-scale multi-modal transit network

This paper describes a practical automated procedure to calibrate and validate a transit assignment model. An optimization method based on particle swarm algorithm is adopted to minimize a defined error term. This error term which is based on the percentage of root mean square error and the mean absolute percent error encompasses deviation of model outputs from observations considering both segment level as well as the mode level and can be applied to a large scale network. This study is based on the frequency-based assignment model using the concept of optimal strategy while any transit assignment model can be used in the proposed methodological framework. Lastly, the model is validated using another weekday data. The proposed methodology uses automatic fare collection (AFC) data to estimate the origin–destination matrix. This study combines data from three sources: the general transit feed specification, AFC, and a strategic transport model from a large-scale multimodal public transport network. The South-East Queensland (SEQ) network in Australia is used as a case study. The AFC system in SEQ has voluminous and high quality data on passenger boardings and alightings across bus, rail and ferry modes. The results indicate that the proposed procedure can successfully develop a multi-modal transit assignment model at a large scale. Higher dispersions are seen for the bus mode, in contrast to rail and ferry modes. Furthermore, a comparison is made between the strategies used by passengers and the generated strategies by the model between each origin and destination to get more insights about the detailed behaviour of the model. Overall, the analysis indicates that the AFC data is a valuable and rich source in calibrating and validating a transit assignment model.

     

Mind the map! The impact of transit maps on path choice in public transit

This paper investigates the impact of schematic transit maps on passengers’ travel decisions. It does two things: First, it proposes an analysis framework that defines four types of information delivered from a transit map: distortion, restoration, codification, and cognition. It then considers the potential impact of this information on three types of travel decisions: location, mode, and path choices.¹ Second, it conducts an empirical analysis to explore the impact of the famous London tube map on passengers’ path choice in the London Underground (LUL). Using data collected by LUL from 1998 to 2005, the paper develops a path choice model and compares the influence between the distorted tube map (map distance) and reality (travel time) on passengers’ path choice behavior. Results show that the elasticity of the map distance is twice that of the travel time, which suggests that passengers often trust the tube map more than their own travel experience on deciding the “best” travel path. This is true even for the most experienced passengers using the system. The codification of transfer connections on the tube map, either as a simple dot or as an extended link, could affect passengers’ transfer decisions. The implications to transit operation and planning, such as trip assignments, overcrowding mitigation, and the deployment of Advanced Transit Information System (ATIS), are also discussed.