Urban Rapid Transit Research Articles

Intelligent Risk Assessment for Dewatering of Metro‐Tunnel Deep Excavations

In recent years, China has been undergoing a metro railway construction boom in order to alleviate the urban traffic congestion problem resulting from the rapid urbanization and population growth in many metropolises. In the construction of metro systems, deep excavations and continuous dewatering for construction of the metro tunnels and stations remain a challenging and high risk task in densely populated urban areas. Intelligent computational methods and techniques have exhibited the exceptional talent in dealing with the complicated problems inherent in the deep excavation and dewatering practice. In this paper, an intelligent risk assessment system for deep excavation dewatering is developed and has been applied in the project of Hangzhou Metro Line 1 which is the first metro line of the urban rapid rail transit system in Hangzhou, China. The specific characteristics and great challenges in deep excavation dewatering of the metro‐tunnel airshaft of Hangzhou Metro Line 1 are addressed. A novel design method based on the coupled three‐dimensional flow theory for dewatering of the deep excavation is introduced. The modularly designed system for excavation dewatering risk assessment is described, and the field observations in dewatering risk assessment of the airshaft excavation of Hangzhou Metro Line 1 are also presented.

Vibration and Performance of a Subway Track System

This paper presents an integrated study of a subway track system with emphasis on the effects of rail pads on the vibration and performance of the system. The study covers analytical, numerical and experimental investigations as well as field measurements of a floating slab track system in an urban rapid transit system. Experimental tests of rail pads are conducted to determine the dynamic characteristics of several types of rail pads. To account for the increase in pad stiffness due to ageing, an energy-based predictive deterioration model is proposed. Field measurements of pad deformations under actual train operations were carried out over three years to validate the proposed model. Rainflow analysis is performed to compute the equivalent ranges and cycle counts to account for the non-periodicity of actual vibrations of rail pads on site. Finite element method is used in both the back analysis for roughness determination and forward analysis for response prediction.

Urban rapid transit network capacity expansion

This paper examines a multi-period capacity expansion problem for rapid transit network design. The capacity expansion is realized through the location of train alignments and stations in an urban traffic context by selecting the time periods. The model maximizes the public transportation demand using a limited budget and designing lines for each period. The location problem incorporates the user decisions about mode and route. The network capacity expansion is a long-term planning problem because the network is built over several periods, in which the data (demand, resource price, etc.) are changing like the real problem changes. This complex problem cannot be solved by branch and bound, and for this reason, a heuristic approach has been defined in order to solve it. Both methods have been experimented in test networks.

Urban rapid transit network design: accelerated Benders decomposition

This paper presents an urban rapid transit network design model, which consists of the location of train alignments and stations in an urban traffic context. The design attempts to maximize the public transportation demand using the new infrastructure, considering a limited budget and number of transit lines. The location problem also incorporates the fact that users can choose their transportation mode and trips. In real cases, this problem is complex to solve because it has thousands of binary variables and constraints, and cannot be solved efficiently by Branch and Bound. For this reason, some algorithms based on Benders decomposition have been defined in order to solve it. These algorithms have been compared in test networks.

Polarized Linear Motor Combined With Levitation Actuators Working in a Partial Vacuum Environment-Application to Swissmetro

Worldwide high speed Maglev (> 400km/h) developments refer to Maglev such as the Japanese JR-Maglev MLX, the German Transrapid and the USA Inductrack Maglev. Other world projects exist such as the Japan HSST ( 400km/h). The authors investigate new possibilities to combine both the propulsion and the levitation. In order to minimize the heat due to the motor levitation and guidance losses, a polarized excitation is proposed. The use of permanent magnet NdFeB for the excitation is still not applied for high speed Maglev, requiring mechanical power greater than 6MW. Such a solution only appears in Urban Rapid Transit Maglev (<160km/h), such as the USA MagneMotion M3 and the General Atomic Urban Maglev. For Swissmetro, the authors study the polarized inductors for the levitation, implying a polarized synchronous linear motor. The polarization is obtained with permanent magnets NdFeB. This paper presents some key issues related to such technical choices. The motor design is described and the power balance is presented. The thermal behavior is analyzed using a numerical platform of the complete vehicle-tunnel system, based on computation of the air flow dynamic.

More tunnel projects to rely less on state funds: M. Page, Tunnels & Tunnelling, 27(10), 1995, pp 18–22

This article discusses plans for extensive tunnelling in Germany, Switzerland and Austria, and how they will be financed. Thousands of km of tunnels and microtunnels are being planned in these countries, for a variety of reasons. For example, growth in prosperity and environmental issues will create a demand, not only for rail and road tunnels, but also for: (1) water and sanitary systems expansion and rehabilitation; and (2) transport and storage of hazardous goods. Germany has a very active urban rapid transit tunnelling programme for light and heavy rail, together with plans for some underground urban ring roads and car parks. A significant Berlin 2000 consortium has been established. Hamburg will have a fourth road tunnel under the River Elbe. Swiss Federal Railways (SBB) plans about 120km of railway tunnels under the Alps, to relieve increasing congestion on trans-Alpine rail routes. Austria is planning several major tunnelling works as part of a programme to upgrade its rail routes. Although all three countries have had long-term infrastructure planning, with extensive public funding of rail and road tunnels, tunnel construction financing is changing there, and several new approaches to private participation in funding are emerging.

Once again, the costs of urban rapid transit

This paper re-examines the question of short-run economies in the provision of rapid-rail transit. In order to satisfy the theoretical requisite that all observations show costs no less than the theoretical minimum implied by a cost function, I estimate here a frontier cost function. The results indicate decreasing returns for all properties in the sample, a change from previous results. There appears to be only a small amount of technical inefficiency in the industry. I also discuss the implications for marginal-cost pricing of these services in the absence of externalities.

Urban electric railway management and operation in Britain and America 1900–14

The debate about the comparative performance of the British and American economies around the turn of the century has involved most industrial sectors. In the case of the railways, the argument goes back at least to 1887, when a critical analysis of English railway operations compared to those of the United States was published. For British railway companies, the years after 1900 were a particularly difficult time especially in the capital market, and many new investment projects were abandoned, although not solely because of adverse conditions in the capital market. A substantial number of these projects were probably of a marginal nature but the eighteen-year period between 1890 and 1908 also saw the development of a new type of railway – the urban rapid transit system. This was in response to two very different factors – the continuing growth of cities and the application of electric power in a form suitable for railway use. The spread of these systems in Britain paralleled their expansion in the United States.

Cost-benefits in underground urban public transportation

There are now more than 80 rapid transit systems worldwide, and the number is expected to grow as the number of cities with populations greater than one million increases. This paper compares the characteristics and limits of four types of urban rapid rail transit systems: commuter railway; metro/subway; light railway; and tramways. General rules regarding costs of such systems are illustrated with examples from several countries. Benefits of underground urban rapid transit systems are discussed with regard to time aspects, passenger loads, environmental effects, safety, impact on urban development and economic implications. The author discusses the issue of costs vs benefits, which involves assessing the financial, qualitative and quantitative impacts of transit systems on the entire community. This paper describes a cost-benefit analysis method developed in 1981 in West Germany to evaluate effects of transportation projects on passengers, the transit authority and the general public. The author concludes with specific recommendations for future studies of cost-benefit analyses and methods. Il y a maintenant plus de 80 systèmes de transit rapide dans le monde, et ce nombre doit s'accroître de beaucoup suite à l'explosion du nombre de villes de plus d'un million d'habitants. Cet article compare les caractéristiques et les limites de quatre systèmes ferroviaires de transport rapide urbain: trains de banlieue, métro, trains légers, et tramways. Les règles générales sur les coûts de tels systèmes sont illustrées avec des exemples de plusieurs pays. Les avantages des systèmes de transport sous terre sont évalués en fonction des aspects de temps, du nombre de passagers, des impacts sur l'environnement, de la sécurité, des effets sur le développement urbain et des implications économiques. L'auteur discute les problèmes de coûts par rapport aux avantages, ce qui implique l'estimation des effets financiers, qualitatifs et quantitatifs des systèmes de transport sur la communauté entière. L'article décrit une méthode d'analyse coût-bénéfice développée en 1981 Allemagne de l'Ouest pour estimer les conséquences des projets de transport sur les passagers, sur le service de transport et sur le public en général. L'auteur conclut ave des recommendations spécifiques pour de futures études d'analyses et de m'ethodes coûts-bénéfices.

Noise generation in railway wheels due to rail-wheel contact forces

In urban rapid transit systems the squeling noise of railway wheels during the passage through narrow curves is very troublesome to passengers and city dwellers. Frequency analyses of measured curving-noise levels show that the bending vibrations of the wheel disks excited by stick-slip motion between the wheel rim and the rail are the main sources of this sound radiation. To get insight into the dynamics of the noise generation it is necessary to understand the bending vibration behaviour of a wheel disk as well as the sound radiation mechanism and the generation of selfsustained oscillations in the contact area. The present paper deals with a theoretical model which comprises all three parts of the problem. In the first part the natural bending vibrations of the wheel are calculated by means of a finite element model. In the second part the forced and self-sustained oscillations are determined using modal expansion techniques. The third part deals with the calculation of the radiated sound pressure and sound power due to wheel oscillations. Here, an acoustical quality level is introduced to classify the various types of wheel disks. The major assumptions in the present paper are rigid rails and point contact between wheel and rail.

NOISE GENERATION IN RAILWAY WHEELS DUE TO RAIL-WHEEL CONTACT FORCES

SUMMARY In urban rapid transit systems the squealing noise of railway wheels during the passage through narrow curves is very troublesome to passengers and city dwellers. Frequency analyses of measured curving-noise levels show that the bending vibrations of the wheel disks excited by stick-slip motion between the wheel rim and the rail are the main sources of this sound radiation. To get insight into the dynamics of the noise generation it is necessary to understand the bending vibration behaviour of a wheel disk as well as the sound radiation mechanism and the generation of self-sustained oscillations in the contact area. The present paper deals with a theoretical model which comprises all three parts of the problem. In the first part the natural bending vibrations of the wheel are calculated by means of a finite element model. In the second part the forced and self-sustained oscillations are determined using modal expansion techniques. The third part deals with the calculation of the radiated sound pre...

Licensing of Safety-Related Equipment of Track-Bound Transportation Systems

One very important aspect of the operation of track-bound transportation systems (e.g. railways, urban rapid transit systems, automated guideway transit systems) is safety. The demand for safe operation is based on statutory requirements. The following paper goes briefly into the philosophy of safety and deals with the problems of verification of safety in connection with the realization of various technologies. It attempts to highlight the importance of verification and licensing conditions and thus show that “the creation of safety” is not enough, it must be verified. The importance of reliability as opposed to safety is also touched on.

The Study for a Way to Introduce Gaming Simulation into Urban Rapid Transit Construction Plan

The Study for a Way to Introduce Gaming Simulation into Urban Rapid Transit Construction Plan

Underground Transit Station Construction in Japan

Technologies used in Japan for constructing underground stations for heavy-rail urban rapid transit systems are described. Two example projects have been chosen that illustrate different approaches which incorporate several advanced engineering features. These examples illustrate the top-down, or reverse construction method, secant-pile walls, and underground mining of stations in soft ground. With higher direct costs and longer durations, the methods discussed here will not offer solutions to all U.S. station construction projects. Nevertheless, there is a lot to be learned from the Japanese about working on congested sites in urban areas, particularly under the tough geotechnical conditions in Japan. Considering total costs, including disruptions to commerce and traffic in urban areas, the bad publicity, loss of citizen and political support, litigation and other factors that are increasingly encroaching on United States construction methods, it is argued that Japanese construction methods might provide attractive alternatives.

Construction noise control for a major urban rapid transit line extension

The northwest extension of the Massachusetts Bay Transportation Authority Red Line Rapid Transit System involves the demolition and reconstruction of the current terminus station—Harvard Square Station, Cambridge—and the construction of three new stations, and associated subway tunnel and track work. This major construction program, scheduled to extend over a five year period, recognizes the potential noise impacts on the densely populated and highly developed communities in which the new construction is to take place. Cambridge, the most significantly affected community, currently has a noise ordinance limiting property line L10 and maximum A‐weighted sound levels due to construction operations. The MBTA has incorporated the Cambridge limits into construction contract documents and has also included limits on noise produced by individual pieces of construction equipment. The construction noise specifications and implementation procedures are described along with the experience to date in actual contract ...

Passenger requirements in an automated transport system : Richardson, J., and Stroud, P.G.Transport and Road Research Laboratory, Department of the Environment, 1975, 151 pp

This report presents the results from an experimental study which provided human factors data on passenger behaviour in relation to certain aspects of vehicle design and station layout on an urban rapid transit system. An extensive series of tests was carried out using full scale mock-up vehicle and platforms to study, inter alia, the effects on vehicle dwell time of: 1 vehicle size; 2 vehicle door size and using separate doors for entry and exit; 3 the number of people in the vehicle, on the platform and inter-changing between the two; 4 overloading the vehicle with passengers; 5 platform size and layout, including the provision of barriers. The tests were mainly carried out using a static vehicle but in some cases the vehicle was moved in and out of the station to determine the effect of vehicle movement, particularly deceleration, on passenger behaviour at the station. The rapid transit system under study will serve as great a proportion as possible of the urban community; the handicapped persons and those inconvenienced with luggage or pushchairs have been given special considerations in the experimental trials. The report also discusses the implication for passenger behaviour, and hence system performance, of choosing certain vehicle and station design features. (A) /TRRL/

Determination of optimal headways for urban rapid transit systems : Lingaraj BP, Chatterjee A and Sinha KC (1974) 1974 joint national meeting of the Operations Research Society of America and the Institute of Management Sciences. Paper available from Arun Chatterjee, Department of Civil Engineering, University of Tennessee, 118 Perkins Hall, Knoxville, Tennessee 37916, U.S.A.

Determination of optimal headways for urban rapid transit systems : Lingaraj BP, Chatterjee A and Sinha KC (1974) 1974 joint national meeting of the Operations Research Society of America and the Institute of Management Sciences. Paper available from Arun Chatterjee, Department of Civil Engineering, University of Tennessee, 118 Perkins Hall, Knoxville, Tennessee 37916, U.S.A.

Routing algorithms for urban rapid transit

A basic routing algorithm is presented for finding optimal routes for cars in a rapid transit system. The algorithm uses predicted path cost, depth-first search, and threshold acceptance to minimize computation cost. It is applicable to synchronous, cycle-synchronous, and trans-synchronous control strategies, and will minimize either departure time, transit time, or arrival time as may be needed. Extensions of the algorithm to allow finding empty cars to answer service requests, to dynamically reroute cars in the system, and to handle multistation routes are presented.

Acoustic Scattering by Reflective Barrier Geometries

Attenuation of sound by barriers is of much practical interest for abatement of highway and urban rapid transit noise. An effective attenuation prediction scheme cannot be based on the usual diffraction from a rigid semi-infinite plane concept because the ground effect creates localized regions of high attenuation. Assuming a coherent line source radiating above a reflecting plane, theoretical expressions are derived for the scattered sound field of semi-elliptic and wedge-shaped acoustically opaque barriers. Theoretical insertion loss predictions, at several measurement locations in the diffracted field, show major dependenceies on the source's position and frequency, but only a minor dependency on barrier shape. Experimental measurements agree favorably with theoretical predictions.

Paper 5: Guided Buses on Segregated Ways

Throughways is the name given to an urban rapid transit system that is based on the use of standard buses operating on ordinary urban roads for part of the route and on reserved tracks, either at ground level or as elevated structure, on sections of routes where traffic congestion would ordinarily restrict the speed and make it difficult to predict schedules. On the reserved tracks the buses are automatically steered by a guidance unit. By this means narrow tracks can be used, and the buses can keep up a higher average speed (which is largely independent of weather) than would be possible with manual steering. The system includes automatic signalling equipment, to ensure safe merging of buses from lay-bys and feeder routes into a main stream operating at high density. This is intended not only to help maintain high schedule speeds and high capacities, even in bad weather or poor visibility, but also to reduce braking and acceleration rates, thus contributing to passenger comfort.