Safer and more efficient terminals: the role of movement, behaviour and evacuation simulation in design

Abstract not available

The use of a biased heuristic by a genetic algorithm applied to the design of multipoint connections in a local access network

This paper presents a genetic algorithm for finding a constrained minimum spanning tree. The problem is of relevance in the design of minimum cost communication networks, where there is a need to connect all the terminals at a user site to a terminal concentrator in a multipoint (tree) configuration, while ensuring that link capacity constraints are not violated. The approach used maintains a distinction between genotype and phenotype, which produces superior results to those found using a direct representation in a previous study.

Estimating the flow rate capacity of an overturned rail carriage end exit in the presence of smoke

While incidents requiring the rapid egress of passengers from trains are infrequent, perhaps the most challenging scenario for passengers involves the evacuation from an overturned carriage subjected to fire. In this paper we attempt to estimate the flow rate capacity of an overturned rail carriage end exit. This was achieved through two full-scale evacuation experiments, in one of which the participants were subjected to non-toxic smoke. The experiments were conducted as part of a pilot study into evacuation from rail carriages. In reviewing the experimental results, it should be noted that only a single run of each trial was undertaken with a limited — though varied — population. As a result it is not possible to test the statistical significance of the evacuation times quoted and so the results should be treated as indicative rather than definitive. The carriage used in the experiments was a standard class Mark IID which, while an old carriage design, shares many features with those carriages commonly found on the British rail network. In the evacuation involving smoke, the carriage end exit was found to achieve an average flow rate capacity of approximately 5.0 persons/min. The average flow rate capacity of the exit without smoke was found to be approximately 9.2 persons/min. It was noted that the presence of smoke tended to reduce significantly the exit flow rate. Due to the nature of the experimental conditions, these flow rates are considered optimistic. Finally, the authors make several recommendations for improving survivability in rail accidents. Copyright © 2000 John Wiley & Sons, Ltd.

An introduction to China's rail transport Part 1: History, present and future of China's railways

In this paper an introduction is given to the history, current situation and future plans of China's railway industry. The history of China's railway is divided into four development phases: the phase in Imperial China, the phase in the Republic of China and the phases before and after the economic rejuvenation of the People's Republic of China. An introduction to the current situation and future plans includes the major projects under construction and development trends of China's railways. The environment of China's railways is also presented. This is the first of two papers on the railway scene in China.

An introduction to China's rail transport Part 2: Urban rail transit systems, highway transport and the reform of China's railways

In this paper, an introduction is provided to some of the components of China's transport system. The authors include the urban rail transit systems, the highway transport systems and its competition for China's railways and the reform of China's railway industry. This is the second of two papers on the situation of rail transport in China.

Modelling collisions of rail vehicles with deformable objects

This study utilized the latest computing techniques to analyze the driver's cab of a railroad vehicle colliding with deformable objects. It explored the differences between a collision with a deformable object and a collision with a rigid object. It also examined the differences between a collision with a large simple shaped object and a collision with a life-like object. Tools of analysis included vehicle dynamics analysis and finite element analysis.

Analysis of the structural characteristics of an intermediate rail vehicle and their effect on vehicle crash performance

In the current paper, the authors present an analysis of the structural characteristics of an intermediate rail vehicle and their effects on crash performance of the vehicle. Theirs is a simulation based analysis involving four stages. First, the crashworthiness of the vehicle is assessed by simulating an impact of the vehicle with a rigid wall. Second, the structural characteristics of the vehicle are analysed based on the structural behaviour during this impact and then the structure is modified. Third, the modified vehicle is tested again in the same impact scenario with a rigid wall. Finally, the modified vehicle is subjected to a modelled head-on impact which mirrors the real-life impact interface between two intermediate vehicles in a train impact. The emphasis of the current study is on the structural characteristics of the intermediate vehicle and the differences compared to an impact of a leading vehicle. The study shows that, similar to a leading vehicle, bending, or jackknifing is a main form of failure in this conventionally designed intermediate vehicle. It has also been found that the location of the door openings creates a major difference in the behaviour of an intermediate vehicle. It causes instability of the vehicle in the door area and leads to high stresses at the joint of the end beam with the solebar and shear stresses at the joint of the inner pillar with the cantrail. Apart from this, the shapes of the vehicle ends and impact interfaces are also different and have an effect on the crash performance of the vehicles. The simulation results allow the identification of the structural characteristics and show the effectiveness of relevant modifications. The conclusions have general relevance for the crashworthiness of rail vehicle design

Comparison of crash dynamics of articulated and non-articulated trains

This paper presents a comparison of impact dynamic performance between articulated trains and non-articulated trains. This is carried out by investigation of the characteristics of the two trains types and analysis of their effects on impact dynamics. The analysis shows that the differences in bogie support positions on the carbody and coupling devices lead to differences in several structural and compositional characteristics. These characteristics result in different impact responses for the two types of train and are directly related to their impact stablity. Articulated trains have stiff connection and integral performance in collisions but with less capability for absorbing impact energy between carriages, whereas non-articulated trains show loose connection and scattered performance in collisions but with more options for energy absorber installation between carriages.

Intrinsic measure of diversity gains in generalised distributed antenna systems with cooperative users

The diversity gains achievable in the generalised distributed antenna system with cooperative users (GDAS-CU) are considered. A GDAS-CU is comprised of M largely separated access points (APs) at one side of the link, and N geographically closed user terminals (UTs) at the other side. The UTs are collaborating together to enhance the system performance, where an idealised message sharing among the UTs is assumed. First, geometry-based network models are proposed to describe the topology of a GDAS-CU. The mean cross-correlation coefficients of signals received from non-collocated APs and UTs are calculated based on the network topology and the correlation models derived from the empirical data. The analysis is also extendable to more general scenarios where the APs are placed in a clustered form due to the constraints of street layout or building structure. Subsequently, a generalised signal attenuation model derived from several stochastic ray-tracing-based pathloss models is applied to describe the power-decaying pattern in urban built-up areas, where the GDAS-CU may be deployed. Armed with the cross-correlation and pathloss model preliminaries, an intrinsic measure of cooperative diversity obtainable from a GDAS-CU is then derived, which is the number of independent fading channels that can be averaged over to detect symbols. The proposed analytical framework would provide critical insight into the degree of possible performance improvement when combining multiple copies of the received signal in such systems.