01046973

Component

The user-equilibrium (UE) assignment is widely used in predictions of travel on roadway systems. It is well known, that under appropriate assumptions, total link flows are uniquely determined by the UE assumption, but route flows are not. Route flows have become increasingly important in practical applications as the variety of analyses performed on traffic assignment results expands. The purpose of this paper is to examine the extent by which results of analyses may be influenced from this issue of non-uniqueness. As a case study, we use a medium size network for the roadway system in Israel. We employ a new assignment algorithm to obtain a precise UE solution, and to determine the set of UE routes in this solution. Random processes are used to generate 450 alternative route-flows UE solutions and 1000 alternative origin-based-link-flows solutions. The effects of differences among solutions are analyzed at the route level and for two types of applications: "select link" analysis and license plates surveys. The results show that for almost every OD pair with multiple UE routes the route flows are nearly completely arbitrary. Substantial arbitrariness remains in aggregate analyses as well; for example for 9% of the links the origin cannot be determined for at least half of the flow.

01042056

07-1335

English

14p

2007

Transportation Research Board 86th Annual Meeting

CD-ROM

Figures (9) ; References (6) ; Tables (2)

Network links; Origin and destination; Route choice; Traffic assignment; Traffic flow; Traffic lanes; Travel; Travel patterns; Trip length

User equilibrium

Israel

Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2007 Paper #07-1335

TRIS, TRB

Feb 8 2007 5:56PM