White Rose University Consortium logo
University of Leeds logo University of Sheffield logo York University logo

Area Speed-Flow Relationships by Micro-Simulation: Sensitivity Issues and Problems with the Tracking Approach When Extended to Multi-Zone Networks

Shepherd, S.P. and May, A.D. (1994) Area Speed-Flow Relationships by Micro-Simulation: Sensitivity Issues and Problems with the Tracking Approach When Extended to Multi-Zone Networks. Working Paper. Institute of Transport Studies, University of Leeds , Leeds, UK.

Full text available as:
[img]
Preview
Text
ITS160_WP430_uploadable.pdf
Available under licence : See the attached licence file.

Download (301Kb)
Published Version: http://www.its.leeds.ac.uk/

Abstract

This working paper is the third in a series relating to the EPSRC funded project, " The definition of capacity in urban road networks : the role of area speed-flow relationships". The paper looks at the sensitivity of the results to the process of modelling blocking-back in NEMIS, for the same 6x6 grid network described by May and Shepherd (1994b).

First of all the blocking-back logic implemented in NEMIS is described. This logic was developed by Shepherd (1990) for use on an arterial network with the intention of blocking cross flows at signalised junctions. When implemented on grid networks with high demands and certain turning ratios this logic can lead to gridlock conditions. The logic implemented in NEMIS caused an irrecoverable gridlock condition i.e. once gridlock occurs it cannot be cleared. Although gridlock conditions may exist for short periods of time in the real world driver behaviour and or external factors combine to relieve the condition eventually. The results will be discussed with and without the blocking-back model implemented in NEMIS for matrix B - heavy inbound traffic.

This work also revealed some problems with the tracking approach described by May and Shepherd (1994a) and the definition of demand when extended from single link/zone networks to multi-zone networks. One of the main problems was that of overlapping in the space-time domain, the amount of overlap increasing as demand is increased.

Item Type: Monograph (Working Paper)
Copyright, Publisher and Additional Information: Copyright of the Institute of Transport Studies, University Of Leeds.
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Environment (Leeds) > Institute for Transport Studies (Leeds)
Depositing User: Adrian May
Date Deposited: 13 Apr 2007
Last Modified: 09 Jun 2014 00:31
Published Version: http://www.its.leeds.ac.uk/
Status: Published
Publisher: Institute of Transport Studies, University of Leeds
Identification Number: Working Paper 430
URI: http://eprints.whiterose.ac.uk/id/eprint/2150

Actions (login required)

View Item View Item