01047029

Component

The problem of estimating origin-destination travel demands from limited observations of road traffic conditions has been conventionally formulated as a network design problem (NDP). The intrinsic bi-level structure of NDP poses both analytical and computational difficulties. In an earlier attempt, we overcame the bi-level structure by decoupling equilibrium conditions. The decoupled formulation, however, requires that traffic counts to be available on all links and to satisfy equilibrium conditions perfectly. This paper proposes a path-based formulation which relaxes the equilibrium conditions but still takes users' route choice behavior into account. The relaxation strategy intends to discourage the use of non-equilibrium paths by incorporating Beckmann's cost function into the objective. Both historical O-D information and path travel times measured from probe vehicles are considered as inputs other than traffic counts. An algorithm based on column generation is devised to solve the relaxed formulation and its convergence is proved. Using a benchmark example, we compare the estimation results obtained from bi-level, decoupled and relaxed formulations, and conduct various sensitivity analysis.

01042056

07-1122

English

27p

2007

Transportation Research Board 86th Annual Meeting

CD-ROM

Figures (3) ; References (23) ; Tables (4)

Benchmarks; Mechanical relaxation; Origin and destination; Sensitivity analysis; Traffic congestion; Traffic control; Traffic counting; Traffic equilibrium

Bilevel model; Decoupling; Network design problem; Path-based algorithms; Relaxation methods (Mathematics)

Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2007 Paper #07-1122

TRIS, TRB

Feb 8 2007 5:44PM