Critical length determination for long and longitudinal slope of expressway based on performance of heavy duty vehicles(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2019年03期
- Page:
- 108-116
- Research Field:
- 交通工程
- Publishing date:
Info
- Title:
- Critical length determination for long and longitudinal slope of expressway based on performance of heavy duty vehicles
- Author(s):
- XU Ting; ZHAO Lei; ZHANG Min; LI Min; LIU Jianbei
- (1. School of Automobile, Changan University, Xian 710064, Shaanxi, China; 2. CCCC First Highway Consultants Co., LTD., Xian 710075, Shaanxi, China)
- Keywords:
- traffic engineering; traffic safety; critical length; speed profile; powertoweight 〖JP〗ratio; heavy vehicle
- PACS:
- -
- DOI:
- -
- Abstract:
- Aimed at the unreasonable combination of different lengths and grades of slopes of expressway in mountainous areas have led to an increase in traffic accidents on long and steep slopes. A model was designed to explore the relationship between the heavyvehicle speed characteristics and slope length after analyzing the speed and stress distribution in moving uphill and downhill taking F3000 heavyhaul vehicle produced which by Shaanxi automobile company as an example. The reasonable critical slope length was determined by simulating the relationship between the speed of heavy vehicles with different specific power and the slope length during uphill and downhill. The research scenario was assumed that the slope of the expressway was 1% to 6%, the initial speed of uphill was 80 km/h and the final speed range was 50 km/h, and the initial speed of downhill was 0 km/h and the final speed was 80 km/h. The relationship between the slope and the speed was calculated through MATLAB simulations. The results show that when going uphill, if the initial speed is 80 km/h, the stable speed is 45 to 61 km/h. When the slope is constant, the higher the specific power of the heavy vehicle, the faster is the decrease in the speed, and the larger the stable speed, the longer is the equilibrium slope required to achieve stable speed. In the downhill process, when the slope is constant, the higher the specific power of the heavy vehicle, the greater the speed increase, the higher is the increase in speed, and further, the greater the steady operation speed, the shorter is the equilibrium slope length to reach the final driving speed. It is not necessary to set a climbing lane when the grade is 1% to 3%. When the slope is greater than 3%, the speed decreases fast for lower specific power of vehicles with a poor climbing performance. It is therefore required to set up a climbing lane or other safety facilities to increase road safety. When heavy vehicles run in the 4%, 5%, and 6% slope range, the thresholds for setting escape lanes are 5.5, 4, 3 km, respectively. The results can provide guidelines for the rational design of mountain highway alignment and road safety protection, as well as the designing of climbing lane and escape lane in order to improve the driving safety of heavy vehicles on the mountain expressway. 6 tabs, 9 figs, 26 refs.
Last Update: 2019-05-23