The outcome show that the length of extra lane is concerned with the traffic flow of the exit and the secondary road,and the reasonable length is recommended as 100～120 m.

The rational length of auxiliary lane and channelization of urban expressway exit have an important role to increase the exit capacity and decrease the influence to expressway traffic flow from exit.

extrapolate the algorithm of additional extent of acoustic baffle by following Jing-Hu High-speed Railway Tentative Provision, approximating the varied denoise effect of acoustic baffle with different distance and height, propose preferred controlled range that shall be taken in acoustic baffle design through field survey.