关键词: 双车道公路, 期望车速, 线形, 交通环境

Abstract: As the upper limit of running speed，expectation speed is the key parameter of the running speed forecasting. In view of current problem that the expectation speed is excessively high in running speed prediction of double － lane road，the relationship between road conditions and drivers’choice of expectation speed are focused; the survey method is used to quantify the effect of road conditions on the expectation speed，which improves the prediction method for expectation speed of double-lane road，and lays a good foundation to test the alignment safety of double － lane road by using driving speed.

Key words: double － lane road, expectation speed, alignment, traffic environment