Forecasting and Appraising Travel Time Variability in Urban Areas
I Black, J Fearon, C Gilliam, Hyder, UK; F Oladeinde, Department for Transport, UK
Forecasting and appraising travel time variability in urban areas using data collected from Global Positioning System (GPS) tracker-equipped vehicles
Recent years have seen a growing interest in monitoring travel time variability (TTV) on the highway network and developing methods to forecast TTV. This paper describes work currently (February 2008) being undertaken for the UK Department for Transport to develop methods for calculating and forecasting TTV using data collected from Global Positioning System (GPS) tracker-equipped vehicles.
Primary data on vehicle location and time can be transformed into data on times taken to traverse different links on the road network. A database has been constructed comprising travel times for individual vehicles on 34 routes (up to 12km long) within the 10 largest urban areas in England for a period of 3 years. This database on individual vehicles has been used to construct a TTV database containing data on the standard deviation of travel time along individual links in these routes as well as journeys comprising more than one consecutive links.
The paper will describe the quality of the database and its usefulness for monitoring TTV. It will also describe the analysis undertaken to understand the impact on TTV of such factors as link/junction characteristics and journey length. This will be followed by indications of appropriate relationships that can be used to predict TTV in urban areas. Finally it will demonstrate how changes in TTV can be incorporated into an assessment framework, thereby providing a monetary estimate of the forecast benefits due to changes in TTV following a policy or scheme intervention.
The work builds on earlier resesarch for the UK Department for Transport that was presented to ETC in 2004.
Association for European Transport