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Abstract: Macroscopic fundamental diagrams (MFD) of traffic for some networks have been shown to have similar shape to those for single links. They have erroneously been used to help estimate the level of travel in congested networks. We argue that supply curves, which track vehicles in their passage through congested networks, are needed for this purpose, and that they differ from the performance curves generated from MFD. We use a microsimulation model, DRACULA and two networks, one synthesizing the network for Cambridge, England, and one of the city of York, England, to explore the nature of performance curves and supply curves under differing patterns of demand. We show that supply curves differ from performance curves once the onset of congestion is reached, and that the incorrect use of performance curves to estimate demand can thus seriously underestimate traffic levels, the costs of congestion, and the value of congestion relief measures. We also show that network aggregated supply curves are sensitive to the temporal distribution of demand and, potentially, to the spatial distribution of demand. The shape of the supply curve also differs between origin–destination movements within a given network. We argue that supply curves for higher levels of demand cannot be observed in normal traffic conditions, and specify ways in which they can be determined from microsimulation and, potentially, by extrapolating observed data. We discuss the implications of these findings for conventional modelling of network management policies, and for these policies themselves. [Copyright &y& Elsevier]

Developing a network for cycle traffic is a complex process, particularly in a dense and heavily motor trafficked city such as London. The London Cycle Network Plus has delivered cycle routes on strategic highways, and local cycling stakeholders have assisted in the design process through cycle route implementation and stakeholder plans. Stakeholders were trained in aspects of highway engineering and used the London cycling design standards as a reference tool. The paper summarises the lessons learnt, and concludes that knowledge from stakeholders is needed to help in the design process, and such intense involvement was novel in transport planning. The current proposals for cycle superhighways and other borough transport schemes seek to build on previous participative successes and also emphasise planning issues in the geographical neighbourhood of routes. [ABSTRACT FROM AUTHOR]

The origins of a road user charging concept for central London and the development of the central London congestion charging scheme are outlined. The paper then explains the objectives and the main features of Transport for London's programme of impacts monitoring of the scheme. It summarises the main results that were obtained. Drawing on the extensive data from the monitoring programme, the paper then compares the patterns of congestion and traffic flows that were observed in the original scheme and in its western extension. This shows how congestion was initially eased as traffic levels were reduced and how it subsequently increased as the effective capacity of the road network was reduced or reallocated. The paper concludes with some reflections on the achievements of the charging scheme. [ABSTRACT FROM AUTHOR]

By the 1990s, the average speed of trips across London was below that at the beginning of the twentieth century--before the car was introduced--and by the end of that decade, public concern over levels of traffic congestion was high. In early 2003, London imposed a congestion charge--a daily charge for driving or parking a vehicle on public roads within central London between the hours of 7:00 a.m. and 6:30 p.m. on workdays. Traffic congestion has declined substantially, and the program is largely popular. This article describes the origins of the London congestion charge, how it overcame practical and theoretical difficulties, and what effects it has had. The introduction of the London congestion charge is, in important respects, a triumph of economics. It represents a high-profile public and political recognition of congestion as a distorting externality and of road pricing as an appropriate policy response. [ABSTRACT FROM AUTHOR]