Why is the speed limit on the He-Da Expressway set at 80 km/h?
2 Answers
The He-Da Expressway has a speed limit of 80 km/h only on certain sections, primarily due to technical conditions affecting interchange areas and tunnel sections. The design speed of the He-Da Expressway is 100 km/h, but it is limited to 80 km/h in areas such as the Dongjiagou Interchange curve and the Jinshan Tunnel. The specific reasons are as follows: 1. Dongjiagou Interchange Curve: Interchanges are critical nodes on expressways and frequent sites of safety incidents, hence the design speed is set at 80 km/h. If the design speed were too high, it would result in insufficient length for deceleration lanes, causing vehicles to enter the ramp at speeds exceeding the required limit. Similarly, acceleration lanes would also be inadequate, leading to lower speeds when merging into the main lane. Both scenarios pose significant safety risks. 2. Jinshan Tunnel: Poor lighting inside the tunnel affects driving visibility. If the design speed were too high, it would be difficult to react promptly in case of sudden emergencies.
Last time I drove on the He-Da Expressway, I noticed the strict speed limits. After asking a friend from the local road administration, I learned that this highway has many sections winding through mountains and hills, like the Changbai Mountain area in Jilin, where there are often continuous stretches of steep downhill curves for over ten kilometers. Driving at night, I once encountered thick fog with visibility less than 50 meters; if I hadn't slowed down in advance, it could have been dangerous. The tunnel clusters are also critical, especially the section from Jingyu to Fusong where tunnels follow one after another, and the sudden changes in lighting can be disorienting. I heard that the accident rate was high in the early years, with trucks overheating their brakes on long downhill stretches and crashing through guardrails. Now, the 80 km/h speed limit throughout is meant to force everyone to drive slower. Actually, driving slower saves fuel—I calculated that the same trip only takes 20 minutes longer, but the safety factor doubles.
