As one of important issues in transportation planning, capacity of road network offers theoretical support to the quality evaluation of urban network in traffic control and management. This paper investigates the capacity of road network from a new perspective in which the experimental traffic engineering concept is adopted through macro traffic simulation and planning with the Cube software. By considering the impact factors on roadway capacity and evaluation index system of road network operational quality, we carried out stress tests over the roadway network and developed a process for conducting such tests. The Cube based process was then used in a field test in the Huairou District, Beijing, where the capacity of the roadway network has been estimated.