When implementing an underground pipeline project, the overall programme should be progressed in accordance with the appropriate regulations and contract provisions, with consideration of physical restrictions, time durations and construction materials. The foregoing restrictions are difficult to change; however, they can be managed with proper advance planning such as clearly defined construction routes and proper work schedules. Hence the efficient management of the work front and manpower to complete the works at the minimum cost is an important issue. Aiming at the minimization of total operating cost, this study considers a number of practical constraints on construction and applies the integer programming technique to construct an optimization model for the assignment of constructionn crew to multiple underground pipelines. The model is solved using the mathematical programming software LINGO. To evaluate the proposed model, a case study has been performed using the preliminary plan of an underground pipeline project in New Tipei City. The test results show that the model performs well and is both more effective and efficient than the manual planning approach. Finally, A numer of sensitivity analyses have also been performed to provide useful references for the decision makers.