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Highway speed limit of 120 km/h is the most effective way to prevent accident

News by ninechip | On 2018-12-19 09:17
With the continuous improvement of vehicle performance and quality, road quality is getting better and better, but the maximum speed limit of expressway 120Km/h cannot be broken for many years. Why should the domestic expressway limit at 120Km/h?
Some developed countries, due to the overall high quality of roads and drivers, the speed limit of expressways is higher than that in China. Germany has no speed limit for some speed, while Italy has a maximum speed limit of 150Km/h. Of course, we can also find law-abiding Japan has a speed limit of 100Km/h with special governor control systems in each car.
In fact, 120Km/h is the domestic reference standard for road design and the road friction coefficient, guardrail strength, lane width, slope, radius of curvature, sign size are designed in accordance with this standard. If road traffic increases traffic, these designs will all be remodified, and existing motorways will face constructive reconstruction, with very high costs. Of course, many users may think that the new highway can be designed to be built in accordance with the higher speed standard, but the problem is that the cost is increased, and the most important thing is that the law currently does not allow the speed to exceed 120Km/h, which undoubtedly leads to high price waste of the road, so the road is still built in accordance with the 120Km/h standard.
Of course, the construction of roads in accordance with the 120Km/h standard does not mean that the speed limit can be set according to 120Km/h. It also requires the comprehensive factors such as road environment and climate, such as tunnels and bridges in mountainous areas and even the speed limit of 80Km/h or 60Km/h.
Besides, drivers' vision, visual field and reaction time are the three most important factors affecting traffic safety. For vehicles traveling at 120Km/h, the reaction distance is: 120x1000x2.5/60=83 (m). If vehicle braking and freewheeling are added, the effective reaction distance is more than 100m. It is assumed that there is an obstacle outside 100m, and you have 3 seconds to react if the speed is 33m/s at 120Km/h. When the speed is 44m/s at 160Km/h you only have 2.2s. For most people, it's not enough. Therefore, when most people encounter an emergency at 160Km/h, they are unable to make a timely and correct reaction.
As the speed increases, the wind resistance increases in a coefficient form, which is why it is difficult for the top speed of a modern traditional diesel locomotive to exceed 500Km/h. The explosive growth of wind resistance makes the vehicle need generator governor speed control.
A speed device in car will significantly increase the energy consumption of vehicles, which is directly reflected in the significant increase of fuel consumption of 100 km. Generally speaking, 100-120 km is the best combination point of vehicle performance, speed, safety and other factors, which is not only fuel saving, environmental protection, but also safe and fast.

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