An intersection control strategy for a short‐headway P.R.T. network

Much PRT development and research is currently being undertaken assuming quasi‐synchronous longitudinal control of guideway vehicles. This method of control has the characteristic that intersection performance has a substantial influence on the efficiency of trip demand processing. An algorithm for the control of a PRT intersection is discussed here, which would appear to have significant advantages over all other known existing stratagems. The stratagem is not only efficient but its flexibility facilitates tailoring to diverse local conditions; furthermore, the algorithm does not require intractable computations or excessive computer memory requirements. The algorithm is described and simulation results are presented. A comparative study is also made between this algorithm and its fore‐runner.     

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.     

Network design for personal rapid transit under transit-oriented development

This study addresses guideway network design for personal rapid transit (PRT) favoring transit-oriented development. The guideway network design problem seeks to minimize both the guideway construction cost and users’ travel time. In particular, a set of optional points, known as Steiner points, are introduced in the graph to reduce the guideway length. The model is formulated as a combined Steiner and assignment problem, and a Lagrangian relaxation based solution algorithm is developed to solve the optimal solution. Numerical studies are carried on a real-sized network, and illustrate that the proposed model and solution algorithm can solve the PRT guideway network design problem effectively.     

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.     

It is time to give the “true PRT” concept a fair test

True Personal Rapid Transit (PRT), in concept and technology, is considerably advanced over PRT as proposed in the 1960s and 1970s. It is one of the few advanced transit concepts—perhaps the only one—that offers a prospect of overcoming the continued serious deficiencies of conventional transit systems. Past criticisms of PRT were often invalid, but even those questions that deserved to be taken seriously then no longer justify a postponement of serious PRT testing. Conventional transit, in spite of over two decades of considerable governmental support, is proving unable to satisfy major transportation needs of American urban areas, which are increasingly dispersed and multi-centered. There is no indication that conventional transit can overcome sufficiently its performance and economic deficiencies. If PRT is not given a chance to be tested, local public officials will continue to be faced with too limited options as between auto-dominated transportation services and high subsidies for inadequate transit solutions.     

The simple,compelling case for PRT

When compared with existing urban modes, Personal Rapid Transit (PRT) offers compelling advantages in every important respect. The desirable attributes of any urban mobility mode are well documented, such as minimal travel time, safety, comfort, low cost, and minimal impacts. These attributes are used to define a hypothetical, ideal urban mode. The ideal mode would possess characteristics such as no waiting, no stops, from anywhere to anywhere service, risk-free, non-polluting, and accessible to everyone at any time. Although not attainable in the real world, the ideal provides a model and benchmark for design much as the Carnot thermodynamic cycle guides the development of internal combustion engines, or ideal gases and perfect fluids are postulated in physics. A matrix format is used to present the characteristics of various modes against the desirable attributes of any mode. Modes presented are the ideal, walking, bicycles, motorcycles, automobiles, taxis, buses, rail transit, Automated Guideway Transit (AGT), and PRT. In all respects, PRT is shown to approach the ideal much more closely than competing modes.     

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.     

Service effectiveness of prt vs collective ‐ corridor transport

A generalised model is used to provide estimates of overall trip times and speed for conventional corridor‐collective transport and PRT. The results demonstrate why traditional forms of transport find difficulty providing an effective service in a city. Short separations between stops are required to minimise walk times but on conventional transport this leads to significant reductions in achievable speed because of the need for frequent stops. It is also shown that there is very little benefit in service effectiveness from LRT/APM/Monorail over buses. PRT is immune to these effects. The present calculations typically show a benefit for PRT of a factor of two or greater in trip time over either bus or LRT/APM.     

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.     

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.     

A PRT airport - Serving a transportation function

Costly and complicated airports have just three basic functions: (1) service, dispatch and recover airplanes; (2) service, process and embark/debark passengers and material; (3) generate operating cost recovery for owner, operator, sponsor. The first function is ground servicing. The second is embarking and loading, with and subsequent recovery of airplanes, unloading and disembarkation. None of the first function require a terminal of any kind. The second function does, and the third function does nothing for air travel. Use major shopping centers for PRT movement, direct to the jetway. No terminal. Place eleven square buildings between the parallel runways, diamond oriented point-to-point, with four parking spaces -the module sides. Airplanes taxi in and away on one center line, 100 feet from the module centered between in-the-ground service connections. PRT connects two story modules, 200 feet on a side. Jetways at each corner also move vertically up and down to load and unload twice as fast, DOWN the jetway, with baggage on conveyors. PRT from neighborhood centers allows passengers to get tickets from local travel agents, and security check from local police. Travel is secure. Parking and the sales tax take is distributed.     

The morgantown PRT: It is still running at West Virginia University

It has been over fifteen years since the Morgantown PRT system went into passenger service. Its start was marked by cost overruns, high operating costs and poor reliability. However over time, these initial problems and difficulties have been overcome, and today the system provides an extremely important and reliable service that links downtown Morgantown with three campuses of West Virginia University. It is still running. This paper provides background on the development of the system and current operating characteristics of this famous transit demonstration project.     

Dependability as a measure of on-time performance of personal rapid transit systems

A comprehensive method for calculating and measuring Dependability of Personal Rapid Transit systems is derived and compared with the more common measure called Availability. Availability is the percentage of all revenue trips that are completed without interruption. It does not take into account the duration of delays of the passengers because of the diffiiculty of gathering the necessary information in conventional transit systems. In PRT systems, vehicle-hours of travel and of delay relate in a statistically simple way to person-hours of travel and of delay. Therefore, in such systems, it is practical to use the performance measure called Dependability that takes into account the inconveince of people as a result of delays. To form a bridge to present practice, it is recommended that both measures be calculated and compared in forthcoming PRT systems. With today's computer systems, this is easily accomplished.     

Review of computer software for traffic engineers

The mid‐1970s saw the initiation of several lengthy research and development programmes in the United Kingdom which culminated in a range of software for the traffic engineer. The early 1980s brought cheap, powerful microcomputers, thereby enabling the facilities offered by the software to be exploited to the full. This article describes the range of programs now available and in common usage for the design and appraisal of traffic management schemes in the United Kingdom, and suggests a few of the areas where some research and development effort is still needed.     

The rider's impression of a simulated trip by PRT

The potential user interest in PRT's and the conditions for their use were studied. As users are unable to express certain opinions about technology they don't know, assessment studies must be close to real life. One way to getting close to reality is through studies in Virtual Reality (VR). Passenger encounters with PRT was studied by in-depth interviews directly after a VR-simulated trip in a real vehicle. The aims of using VR-technology seems to have been achieved. Many of the subjects had the impression of a real trip, some of them also of having travelled high above ground. All subjects were in favour of PRT and thought they would utilize it. They had confidence in the automatic control devices, although they wanted more information and better design of the safety system. The greatest conflict was the encroachment on the cityscape. Many of the subjects did not accept the impact of the guideways on the old city environment. However these views contrast with the desired accessibility.     

Demand management in suburban settings

This paper provides findings from a review of employer based demand management strategies for reducing traffic congestion in several areas of the United States. The research was carried out by K.T. Analytics, Inc. in 1989 under a contract with the Federal Department of Transportation, Transportation Systems Center. Relying on a review of employer based programs in 26 sites, as well as selected literature, the paper draws conclusions about the effectiveness of employer based transportation systems management (programs to encourage carpooling, transit, biking, cycling, walking and flextime) and parking management (preferential parking for carpoolers, removal of parking subsidies, and other measures) aimed at reducing solo driving and peak period commuting.Several conclusions are offered for local planners and policy makers. Demand Management programs can be effective in reducing traffic congestion, provided they are targeted to larger employment centers, accompanied by transit development, high occupancy vehicle incentives and parking management strategies, especially pricing. Flextime should not be encouraged without careful evaluation as it may discourage ridesharing. Guaranteed ride home services appear promising and deserve attention. With all strategies, long term vigilance will be necessary as programs are susceptible to change over time. Stringent public policies do not appear necessary for development of effective programs. Ordinances should require plans not specific strategies, as it is difficult estimating the probable effectiveness of particular strategies. Ordinances should contain sanctions for employers not carrying out agreed to plans, and should include fees and financing to support public sector review of plans and on-going monitoring.     

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.     

Bike Share: A Synthesis of the Literature

This paper begins by providing an overview of bike share programs, followed by a critical examination of the growing body of literature on these programs. This synthesis of previous works, both peer-reviewed and gray, includes an identification of the current gaps in knowledge related to the impacts of bike sharing programs. This synthesis represents a critically needed evaluation of the current state of global bike share research, in order to better understand, and maximize the effectiveness of current and future programs. Several consistent themes have emerged within the growing body of research on bike share programs. Firstly, the importance bike share members place on convenience and value for money appears paramount in their motivation to sign up and use these programs. Secondly, and somewhat counter intuitively, scheme members are more likely to own and use private bicycles than nonmembers. Thirdly, users demonstrate a greater reluctance to wear helmets than private bicycle riders and helmets have acted as a deterrent in jurisdictions in which helmets are mandatory. Finally, and perhaps most importantly from a sustainable transport perspective, the majority of scheme users are substituting from sustainable modes of transport rather than the car.     

发挥科技优势 实现交通安全发展——六个安全类西部项目成果推介

从2006年起,西部交通建设科技项目在公路、水路建设工程安全生产方面相继有六个科研项目立项开展相关研究。内容涵盖了工程安全技术标准研究,公路、隧道、桥梁、内河港口工程施工重大危险源辫识及事故隐患预警、预报、防治和评价技术研究等方面。目前这六个研究项目虽尚处于在研阶段,但所取得的阶段性研究成果已为行业的安全生产监管、安全监管人才培养和重点建设项目的安全生产提供了技术支持。本篇对这六个安全类西部项目研究情况进行介绍,以供参考。