Institute of Transportation, MOTC

　　The Pick Up and Delivery Problem with Time Windows (PDPTW) was solved via the proposed Guided Adaptive Ant Colony System (GAACS), which was integrated by the Guided Local Search (GLS) and Adaptive Ant Colony System (AACS) proposed by Lee Tai-Lin, etc. However, in order to solve the PDPTW more efficiently and effectively, a PDPTW was transferred to be a new similar PDP (SPDP) without time window via the Time Window Partitioning and Discretization Strategy. In order to show the contribution of the GAACS, 18 Solomon benchmark VRP problems were transferred to be PDPTW problems via the method developed by Lau and Liang. According to the computation results, we obtained the average percentages of errors of the best published solutions among18 PDPTW test instances, with 1.80% and an average computation time of 25.9 minutes. This shows that our proposed GAACS method can solve PDPTW accurately in a reasonable time.