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Using a simple piecewise linear exit-flow function, a cell-based variant of the Merchant-Nemhauser (M-N) model is proposed for the system optimum (SO) dynamic traffic assignment (DTA) problem. Once augmented with additional constraints to capture cross-cell interactions, the model becomes a linear program that embeds a relaxed cell transmission model (CTM) for traffic propagation. The proposed cell-based M-N model is different from the existing CTM-based SO-DTA models in that (1) it does not require intersections to be standard merge and diverge; and 2) it does not directly solve for cell-to-cell flows. Generally, the proposed model has a simpler constraint structure and is easier to construct. Path marginal costs are defined using a recursive formula that involves a subset of multipliers from the linear program. This definition is then employed to interpret the necessary condition, which is a dynamic extension of the Wardrop's second principle. An algorithm is presented to solve the flow holding back problem that is known to exist in many existing SO-DTA models. A numerical experiment is conducted to verify the proposed model and algorithm.

01147878

10-0367

English

24p

2010

Transportation Research Board 89th Annual Meeting

DVD

Figures (4) ; References; Tables (4)

Dynamic traffic assignment; Intersections; Marginal costs; Real time information; Traffic flow; Traffic models; Travel surveys

Cell transmission models; System optimal models

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

Transportation Research Board Annual Meeting 2010 Paper #10-0367

TRIS, TRB

Jan 25 2010 10:12AM