Abstract:From the view point of the affection of investment on traffic network capacity,a new kind of expressway investment optimization method based on the cell transmission model (CTM) theory was put forward.The cell transmission model was improved in order to realize the local ramp control.A particle swarm expression method for the meta cell capacity optimization problem was constructed by using the particle swarm intelligent optimization method.And the total mileage (TDT) and system delay (TD) were defined as a measure of the performance of expressway system.The calculation results show that before the investment,the TDT is 12 004 874 m,the TD is 3 582 405.1 s,and after investment,the TDT is 13 128 283 m,increased by 1 123 409 m,the TD is 3 537 468.7 s,reduced by 44 936.4 s.The results show that the new optimization method makes the total mileage significantly grow and the total delay significantly reduce.The performance of the entire road network is also improved.The investment optimization method can better solve the optimization problem of expressway investment.