Abstract
To analyze the influence of the distance between tunnels at the bridge-tunnel junction in the mountainous area on the driving safety under crosswind, a vehicle dynamics model is established by Carsim software. Under the conditions of different driving speeds (60km/h, 80km/h and 100km/h), different wind scales (level 6–9) and three alignment combinations of the tunnels (tunnel-straight road-tunnel, tunnel-curving road-tunnel, tunnel-the combination of straight and curves road-tunnel), the vehicle’s lateral offset and lateral force coefficient are used as evaluation indexes to study the influence of distance between tunnels on driving safety. When the distance is small, the lateral offset and lateral force coefficient of vehicle driving on the bridge-tunnel junction increase firstly and then decrease as the distance increases. But the changes of the lateral offset and lateral force coefficient are not synchronized, and the peak value of the lateral force coefficient occurs earlier than the lateral offset. Finally, the minimum safety spacing of each condition and speed limits for different distances are proposed. Under the condition of the straight-tunnel, 20m distance between tunnels cannot ensure the driving safety when the wind scale reaches level 9, and the road should be closed. Under the conditions of the curve and the combination of straights and curves, driving safety cannot be maintained at each spacing at wind scale level 8 and 9, and the road should be closed. However, when the wind speed is level 6 or 7, speed limits can be adopted to ensure driving safety. The results suggest that vehicles’ lateral offset and lateral force coefficient can be effectively reduced by reducing the driving speed or increasing the distance between tunnels, so the risk of accidents caused by the crosswind can be reduced.
Highlights
There are about 4.7 million traffic accidents every year, more than 200,000 traffic accidents of which cause casualties and the number of fatality accounts for 21% of the total number of casualties
Wind tunnel test and numerical simulation were used to study the vehicle model, and the results showed that the aerodynamic characteristics of vehicle are affected by wind speed, wind directions and road alignment [10]
VEHICLE DYNAMIC ANALYSIS UNDER CROSSWIND CONDITIONS When the vehicle runs on the bridge-tunnel junction in the mountainous area, the vehicle is subjected to the gravity, support and friction, and subjected to the mutually perpendicular aerodynamic forces generated by the wind and the aerodynamic moment
Summary
There are about 4.7 million traffic accidents every year, more than 200,000 traffic accidents of which cause casualties and the number of fatality accounts for 21% of the total number of casualties. According to the crash data from Zhang’s study (2014), from 2006 to 2008, 1220 crashes were reported in Su-Chang section of Hu Ning Expressway in plain area, with. The cash rate of 0.45, with the crash rate (crashes per million vehicle · km) of 0.45; while the crashes number reported on the typical mountainous expressway of north Guangdong section of Jing Zhu Expressway was 1564, with the crash rate of 0.79, which is 0.34 higher than that in plain area. Bridges and tunnels account for a large proportion in mountainous expressways to optimize the road alignment and shorten the mileage. At bridge-tunnel junctions, the driving is greatly affected by
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