Traffic peak spreading in congested urban environments Traffic peak spreading in congested urban environments

The paper will describe the results of research recently completed, funded by Transfund New Zealand, into the phenomenon of traffic peak spreading in congested urban environments. The work looked specifically at two facets: 4 the extent to which traffic peak spreading has been observed and the underlying behavioural aspects 4 how (if) traffic peak spreading is modeled in different countries and the consequences for scheme evaluation. In terms of the former, data has been collected from a number of key sites, in the urban areas of Wellington and Auckland. This includes some data from an earlier study which is being ‘revisited’ and its forecasts re-examined. Although comprehensive time series data has proved elusive in some cases, there is sufficient evidence in New Zealand and overseas to demonstrate the occurrence of peak spreading conclusively. Information on the modelling of traffic peak spreading has been collected from a number of countries, although it would appear that in many cases it is left to the modeller’s discretion. Elasticity approaches appear to be most tractable, although in the UK a number of highly sophisticated, scheduling type approaches have been developed and piloted. Not unexpectedly, these can be very “data hungry” and go hand-in-hand with other modelling techniques such as time slicing. It is particularly noteworthy that time-of-day choice is now seen as being second in its importance in the choice process after route choice. Reports of the impact of traffic peak spreading on scheme evaluation have to date proved to be few in number, although this is not the case with the wiser issue of “induced traffic” which generally includes peak spreading. Contact author [email protected], [email protected] Booz Allen Hamilton PO Box 10926, Wellington, New Zealand Ph 64 4 915 7777 Fax64 4 915 7755