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The choice of intersection type in a road network is one of the most important decisions to be made in transportation engineering. Capacity and level of service are the two main factors considered in the type of intersection design, but safety and economy should also be taken into account when determining the intersection type since these are equally important. A number of parameters can be used to evaluate the performance of an intersection, including travel time, average delay, queue length, fuel consumption and vehicle exhaust emissions. Adding safety and construction costs to these parameters makes decision-making more difficult. In this study, the analytic hierarchy process (AHP) was used as a multi-criteria decision approach to overcome this problem. Three intersection types were modelled and tested using Vissim software in line with the above parameters. An AHP model was then generated using the Vissim results and the AHP results and applicability were analysed. [ABSTRACT FROM AUTHOR]

In previous studies, little attention has been paid to developing methods for estimating passenger car equivalent (PCE) factors under oversaturated conditions. This paper presents a new method to estimate PCE factors for heavy vehicles based on the assumption that backward wave velocities keep consistent under oversaturated conditions. As the variations of backward wave velocities in mixed flows will be minimal if the traffic stream is uniform, a minimum relative standard deviation optimising model is given based on backward wave velocity. The traffic data drawn from I-80 datasets provided by the next generation simulation are utilised to analyse this method and prove the assumption. In view of the limitation of empirical data, Vissim microscopic traffic software is used to simulate oversaturated traffic flow under different percentages of heavy vehicles. The results show that the effects of heavy vehicles under oversaturated conditions are greater than those under free-flow conditions and the proportion of heavy vehicles has a major impact on the PCE factors. [ABSTRACT FROM AUTHOR]

Roundabouts are a widespread form of junction globally, and are particularly common in the UK. This study focuses on the entry capacity at roundabouts under adverse conditions of weather and light in order to determine the extent to which entry capacity is reduced, and the impact that this has on current practical design. So far no specific studies have attempted to quantify this effect. The study was limited to conventional at-grade, normal-size, non-signalised roundabouts in urban areas. Data were collected in 1998 using video capture techniques at four different sites with a total of 13 approaches, comprising 37 entry lanes. The data were transcribed and classified to exclude those minutes of data which did not satisfy the preset traffic criteria, resulting in the extraction and utilisation of 7721 minutes of detailed entry-lane based data. The entry capacities were classified according to whether the conditions were: dry and light; dry and dark; wet and light; and wet and dark. The results identified that wet and dark conditions had a substantial effect on the entry capacity of urban normal-size roundabouts. Entry capacity was found to be reduced by 14% under dry-dark, 17% under wet-light, and 25% under wet-dark conditions. The paper sets out the main practical implications of these findings for design engineers. [ABSTRACT FROM AUTHOR]

A traffic accident results from the combination of various factors each of which plays a role in its occurrence. It is logical that accidents with different causes should not be considered together as accident cause is one of the most important factors for prioritising high crash road segments. In the present study, the main cause of an accident in a high crash road segment were identified and then the accidents in each segment was classified based on their cause. A new model was developed for prioritising high crash road segments based on the causes of accidents. This model is different from the current models and renders different and more accurate prioritisation results. According to the developed model, a segment may be compared with another and identified to be highly accident-prone with the same cause, whereas, the total number of accidents that occurred in the former may be less than that in the latter. The model was evaluated based on real data collected from highway segments in Tehran. [ABSTRACT FROM AUTHOR]

The Victoria line, extended to Brixton by July 1971, was London's first completely new underground line since the 'tube boom' of the early twentieth century. The new line created connections between the underground and national rail networks, and relieved congestion on London's transport network. Three decades later, Brixton station was at the forefront of a new challenge, this time to improve accessibility of the London Underground network to disabled and encumbered passengers. In 2001 work began to provide step-free access from street to platform levels at Brixton station, to alleviate congestion within the station, and to harness additional benefits by constructing new office and retail facilities. This paper describes the construction, emergency preparedness, site safety, contract administration and assurance aspects of delivering the project. The project successfully executed demolition, building construction, structural, tunnelling and services works while maintaining the safe and effective operation of the station. A number of recommendations are made to assist in the execution of similar projects. [ABSTRACT FROM AUTHOR]

The Highways Agency's National Traffic Control Centre (NTCC) became fully operational in November 2003. The services provided by the control centre are key to satisfying the objectives of providing better information to travellers and ensuring more reliable journeys. This paper describes the policy context within which the control centre has been delivered; the means by which it collects data on conditions on England's motorway and all-purpose trunk road network; how those data are analysed; and the means by which information is disseminated to the general public. These services are providing the catalyst for the development of traffic information delivery tools by the Agency and private sector information providers. [ABSTRACT FROM AUTHOR]

The article presents information on several research papers related to traffic engineering presented at the Institute of Civil Engineers. The paper "Transport engineering--a future paved with gold?" by T. Ridley explains that transport engineering offers a potentially rich and fulfilling career, not just financially but in terms of the holistic service that transport engineers can offer society long into the future. The paper "Congestion charging: selling the concept," by S. Ison discusses the problem of increasing urban traffic worldwide, which is leading to increasing problems of congestion and environmental degradation.

The author introduces himself to the readers of the "Transport" journal. As the new honorary editor and chair of the editorial advisory panel, he provides an insight about his work, experience and research interests. He also offers a tribute to his predecessor Martin Roach and the four other members of the editorial advisory panel who completed their terms in 2007. The author encourages readers to offer their suggestions for the future issues of the journal.