To optimize the geometric design of dedicated freight corridors on highways and reduce the probability of truck accidents

PC-Crash software was used to conduct accident simulation tests with speed

horizontal curve radius

longitudinal slope

superelevation slope

hard shoulder width

widen value of curve

adhesion coefficient

and vehicle type (heavy trucks and articulated trains) as risk factors. The significant risk factors were screened by binary Logistic regression analysis

and the prediction model of roadside accident probability on dedicated freight corridors was constructed. Based on the probabilistic prediction results and the thought of "cumulative frequency curve method"

the probability thresholds of potential blackspot and frequent blackspot of roadside accidents were given

and the identification method of roadside accident blackspot on dedicated freight corridors was proposed. In view of the sections with frequent occurrence of roadside accidents on dedicated freight corridors

the optimization geometric design of dedicated freight corridors was carried out by using classification and regression tree (CART) algorithm. Results show that the importance of significant risk factors on roadside accidents from the largest to the smallest was as followings: speed

horizontal curve radius

adhesion coefficient

vehicle type

hard shoulder width

longitudinal slope

and superelevation slope. For the dedicated freight corridor section with horizontal curve radius of R≤400 m and operating speed of 60 km/h＜v≤80 km/h

the longitudinal slope should be ＜4%; if this design requirements were not met

the superelevation slope should be ≥4%. For the section of dedicated freight corridor with operating speed of 80 km/h＜v≤100 km/h and horizontal curve radius of 400 m＜R≤800 m

the hard shoulder width should be ≥2.25 m. Additionally

increasing the hard shoulder width had a significant effect on reducing the risk of roadside accidents for heavy trucks.