Control of personal rapid transit systems

The problem of precise longitudinal control of vehicles so that they follow predetermined time-varying speeds and positions has been solved. To control vehicles to the required close headway of at least 0.5 sec, the control philosophy is different from but no less rigorous than that of railroad practice. The preferred control strategy is one that could be called an “asynchronous point follower.” Such a strategy requires no clock synchronization, is flexible in all unusual conditions, permits the maximum possible throughput, requires a minimum of maneuvering and uses a minimum of software. Since wayside zone controllers have in their memory exactly the same maneuver equations as the on-board computers, accurate safety monitoring is practical. The paper discusses the functions of vehicle control; the control of station, merge, and diverge zones; and central control.     

Safe design of personal rapid transit systems

The safety of personal rapid transit systems involves careful attention to all features of the design such as the use of a hierarchy of fault-tolerant redundant control systems, bi-stable fail-safe switching, back-up power supplies, vehicle and passenger protection, and attention to the interaction of people with the system. Safety, together with reliability and adequate capacity, must be achieved while making the system economically attractive, hence techniques to achieve these goals at minimum life-cycle cost are primary in PRT design. Building on theory of safe, reliable, environmentally acceptable, and cost-effective design of PRT systems developed during the 1970′s, in 1981 the author and his colleagues initiated design of a new PRT system, now called Taxi 2000. The paper describes the relevant features of Taxi 2000 and principles of safe design incorporated into it.     

Synchronous or clear-path control in personal rapid transit systems

This note derives an equation for the ratio of the maximum possible station flow to average line flow in a personal rapid transit or dual-mode system using fully synchronous control. It is shown that such a system is impractical except in very small networks.     

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.     

Designing personal rapid transit (PRT) networks

This paper presents a heuristic method for designing a PRT network. Because the PRT system operating characteristics and performance measures differ widely from those of conventional transit technologies, an algorithm for the PRT network design problem (NDP) is derived by using concepts from some current NDP algorithms. We minimize the sum of passenger travel time cost, construction cost, vehicle cost and operational costs, subject to an available budget of guideway, a maximum number of vehicles and given link capacities. Starting with a well-connected initial network, the algorithm eliminates and adds links iteratively as it searches for a near-optimal solution. If this solution satisfies the budget constraint, it is considered to be acceptable. Otherwise, additional links are deleted until a feasible near-optimal solution is obtained. The link elimination phase of the algorithm only considers half of the links at a time which greatly decreases computing time. None of the links in an acceptable solution will be overloaded.     

Bus rapid transit systems: a comparative assessment

There is renewed interest in many developing and developed countries in finding ways of providing efficient and effective public transport that does not come with a high price tag. An increasing number of nations are asking the question—what type of public transport system can deliver value for money? Although light rail has often been promoted as a popular ‘solution’, there has been progressively emerging an attractive alternative in the form of bus rapid transit (BRT). BRT is a system operating on its own right-of-way either as a full BRT with high quality interchanges, integrated smart card fare payment and efficient throughput of passengers alighting and boarding at bus stations; or as a system with some amount of dedicated right-of-way (light BRT) and lesser integration of service and fares. The notion that buses essentially operate in a constrained service environment under a mixed traffic regime and that trains have privileged dedicated right-of-way, is no longer the only sustainable and valid proposition. This paper evaluates the status of 44 BRT systems in operation throughout the world as a way of identifying the capability of moving substantial numbers of passengers, using infrastructure whose costs overall and per kilometre are extremely attractive. When ongoing lifecycle costs (operations and maintenance) are taken into account, the costs of providing high capacity integrated BRT systems are an attractive option in many contexts.     

A note on fare policy in personal rapid transit

The choice of fare policy is more flexible in personal rapid transit than in conventional transit and has some unique aspects. The implementation of fare policies as a function of distance are discussed, and, following a discussion of how the fare would be collected in a PRT system, consideration is given to whether the fare should be per person or per vehicle.     

Ridership drivers of bus rapid transit systems

We have collected information on 46 bus rapid transit (BRT) systems throughout the world to investigate the potential patronage drivers. From a large number of candidate explanatory variables (quantitative and qualitative), 11 sources of systematic variation are identified which have a statistically significant impact on daily passenger-trip numbers. These sources are fare, headway, the length of the BRT network, the number of corridors, average distance between stations; whether there is: an integrated network of routes and corridors, modal integration at BRT stations, pre-board fare collection and fare verification, quality control oversight from an independent agency, at-level boarding and alighting, as well as the location of BRT. The findings of this paper offer important insights into features of BRT systems that are positive contributors to growing patronage and hence should be taken into account in designing and planning BRT systems.     

A review of the state of the art of personal rapid transit

The paper begins with a review of the rational for development of personal rapid transit, the reasons it has taken so long to develop, and the process needed to develop it. Next I show how the PRT concept can be derived from a system‐significant equation for life‐cycle cost per passenger‐mile as the system that minimizes this quantity. In the bulk of the paper I discuss the state‐of‐the‐art of a series of technical issues that had to be resolved during the development of an optimum PRT design. These include capacity, switching, the issue of hanging vs. supported vehicles, guideways, vehicles, control, station operations, system operations, reliability, availability, dependability, safety, the calculation of curved guideways, operational simulation, power and energy. The paper concludes with a listing of the implications for a city that deploys an optimized PRT system.     

An integrated measure of accessibility and reliability of mass transit systems

The growth of a city or a metropolis requires well-functioning transit systems to accommodate the ensuing increase in travel demand. As a result, mass transit networks have to develop and expand from simple to complex topological systems over time to meet this demand. Such an evolution in the networks’ structure entails not only a change in network accessibility, but also a change in the level of network reliability on the part of stations and the entire system as well. Network accessibility and reliability are popular measures that have been widely applied to evaluate the resilience and vulnerability of a spatially networked system. However, the use of a single measure, either accessibility or reliability, provides different results, which demand an integrated measure to evaluate the network’s performance comprehensively. In this paper, we propose a set of integrated measures, named ACCREL (Integrated Accessibility and Reliability indicators) that considers both metrics in combination to evaluate a network’s performance and vulnerability. We apply the new measures for hypothetical mass transit system topologies, and a case study of the metro transit system in Seoul follows, highlighting the dynamics of network performance with four evolutionary stages. The main contribution of this study lies in the results from the experiments, which can be used to inform how transport network planning can be prepared to enhance the network functionality, thereby achieving a well-balanced, accessible, and reliable system. Insights on network vulnerability are also drawn for public transportation planners and spatial decision makers.     

Development of multimodal performance measures for transit systems in New York State

The New York State Department of Transportation was required to certify as to the economy and efficiency of transit operators participating in the State's public transportation operating assistance program. This paper describes the efforts undertaken to meet this mandate.Discussed are past efforts to link performance measures to funding programs; reasons for modifying measures which had been used in previous efforts; and some of the problems and issues raised by the use of such criteria. The paper identifies 15 performance measures being used by New York State in its evaluations, the actual ranges encountered in the transit operations being funded through the state program, and tentative acceptable and desirable levels of those measures which the Transportation Department is using in its evaluation. The role these measures play in the state's operating assistance policy decision process is also described.     

Multiple period optimization of bus transit systems

Analytic models are developed for optimizing bus services with time dependence and elasticity in their demand characteristics. Some supply parameters, i.e. vehicle operating costs and speeds are also allowed to vary over time. The multiple period models presented here allow some of the optimized system characteristics (e.g. route structure) to be fized at values representing the best compromise over different time periods, while other characteristics (e.g. service headways) may be optimized within each period. In a numerical example the demand is assumed to fluctuate over a daily cycle (e.g. peak, offpeak and night), although the same models can also be used for other cyclical or noncyclical demand variations over any number of periods. Models are formulated and compared for four types of conditions, which include steady fixed demand, cyclical fixed demand, steady equilibrium demand and cyclical equilibrium demand. When fixed demand is assumed, the optimization objective is minimum total system cost, including operator cost and user cost, while operator profit and social welfare are the objective functions maximized for equilibrium demand. The major results consist of closed form solutions for the route spacings, headways, fares and costs for optimized feeder bus services under various demand conditions. A comparison of the optimization results for the four cases is also presented. When demand and bus operating characteristics are allowed to vary over time, the optimal functions are quite similar to those for steady demand and supply conditions. The optimality of a constant ratio between the headway and route spacing, which is found at all demand densities if demand is steady, is also maintained with a multi-period adjustment factor in cyclical demand cases, either exactly or with a relatively negligible approximation. These models may be used to analyze and optimize fairly complex feeder or radial bus systems whose demand and supply characteristics may vary arbitrarily over time.     

The impact of a new rapid transit system on traffic on parallel highway facilities

This study analyzes data of traffic crossing San Francisco Bay and passing through the Berkeley Hills via Caldecott Tunnel to determine the effect of the opening in 1974 of the Bay Area Rapid Transit System (BART) transbay line. There was a sudden shift in trend lines in 1974; vehicle volumes dropped, transit patronage jumped, but total person trips in the short run followed roughly the trends of the previous eight years. Since 1974, the growth rate in person trips through the Berkeley Hills appears to have remained about the same, while transbay vehicle and transit traffic have increased at a more rapid rate. The increase in transit patronage is particularly noticeable between the morning and afternoon peaks and probably represents new trips by shoppers and sightseers. Whereas other factors, such as the increase in the price of gasoline between October 1973 and July 1974 may have contributed a little to the sudden change in the long‐range trends in 1974, it is believed that the major cause was the opening of the BART network to transbay travel.

     

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.     

An analysis of the 1968 rapid transit vote in Los Angeles

Analysis of the results of past mass transit bond issues can aid transportation planners in understanding and anticipating voter behavior. This paper reports the results of an analysis of the 1968 rapid transit bond issue vote in Los Angeles, California. The simple relationships of the vote to a variety of possible explanatory variables are first examined. An attempt to assess the relative independent importance of these variables and to offer a partial explanation of the vote using multiple regression analysis is then presented. Variables found to have had the greatest impact on the vote are proximity to the proposed transit system, income-level, and ethnicity. Variables found to have had little or no effect, on the other hand, are population density, age, partisanship, and election turnout rate. The analysis indicates that the frequently used mood-of-the-electorate explanation of bond-issue failures in general, and transit proposals in particular, underestimates the quality of the electoral decision. The electorate does make rational distinctions, and future bonding attempts will confront voters capable of perceiving the utility to them of proposed transit systems and voting accordingly. The policy implications of this analysis suggest that the design of future mass transit proposals should, firstly more explicitly attempt to incorporate the preferences of middle-income voters, and secondly, be part of a comprehensive transit plan for the entire metropolitan area.