Engineering design is a highly knowledge-intensive task. Current practice of engineering design usually refers to documentations of similar design projects conducted previously. Time-consuming design works are inevitable if the scope of work for the new project exceeds the scope of referred projects, and thus the cost and time required for the new design work are expected to increase. To improve such a situation, the present research proposes a Knowledge-based engineering design assistant for road construction project (EDA-Road) to assist engineers in performing road design works. With the assistance of seven developed functional modules, the engineers are able to shorten the time for finding useful historical design alternatives. Such a system does not only reduce the cost of design, but also provide a vehicle for knowledge transfer from previous to new engineering design project.