Abstract: In urban transportation network,two-way road flows may be disequilibrium during some time(e. g. on/off duty).Aiming to make full use of the existing road resource and reduce transportation congestion,this paper proposed a two-way road lane reallocating approach under asymmetric flows,and established a corresponding discrete bi-evel programming model in which transportation managers at the upper level minimize the total system co st by reallocating lanes on the two-way road Then,a chaotic optimization algorithm for the bi-level programming model is proposed Finally,the proposed approach was verified through the famous Sioux Falls network.

Key words: two-way road, variable lanes, bilevel programming, chaotic optimization