Reliability of travel times in transportation systems and particularly freeway networks has gained considerable interest in the past decade. In this paper we present two measures for travel time reliability which could be exploited by both researchers and practitioners. Since day-to-day variability of route travel times freeway corridors is generally considered closely related to the reliability of a road network, we argue that both skew and width of the day-to-day distribution of route travel times are relevant indicators for unreliability. Consequently, we propose two reliability measures, based on three characteristic percentiles, that is, the 10th, 50th and 90th percentile for a given route and time of day (TOD) and day of the week (DOW) period. High values of either measure indicate high travel time unreliability. However, the weight of each measure on travel time reliability may be application or context specific.
The practical value of these particular measures amongst other things that they can be used to construct so-called reliability maps, which visualize not only the unreliability of travel times for a given DOW/TOD period, but also help identify DOW/TOD periods in which it is likely that congestion sets in (or dissolves). This means identifying the uncertainty of start, end and hence length of morning and afternoon peak hours. Also, the measures may be used in discrete choice models as explanatory variables for driver uncertainty.
|Title of host publication||TRAIL Conference Proceedings, selected papers|
|Editors||PHL Prof.dr.ir. Bovy|
|Place of Publication||Rotterdam|
|Publisher||TRAIL Research School|
|Number of pages||19|
|Publication status||Published - 2004|
|Event||8th TRAIL Congress 2004 - Rotterdam|
Duration: 19 Nov 2004 → 23 Nov 2004
|Publisher||TRAIL research School|
|Conference||8th TRAIL Congress 2004|
|Period||19/11/04 → 23/11/04|