What does design speed refer to in highway design?

[AvaFitz]

In highway design, the design speed refers to the maximum speed of the highway, intended to ensure safe driving for motorists. Highway regulations: Article 78: According to the "Regulations for the Implementation of the Road Traffic Safety Law of the People's Republic of China," highways must indicate lane speeds. The maximum speed must not exceed 120 km/h, and the minimum speed must not be lower than 60 km/h. The maximum speed for small passenger vehicles on highways must not exceed 120 km/h, while other motor vehicles must not exceed 100 km/h, and motorcycles must not exceed 80 km/h. Posted speed limits: This refers to the speed indicated by speed limit signs and markings on the highway. The specific speed limit is determined by the transportation authorities based on the highway's design speed, functional type, geometric alignment characteristics, traffic flow, roadside environment, and other factors. Legal speed limits: On road sections without speed limit signs, drivers must adhere to the speed limits stipulated by laws and regulations, as per the "Road Traffic Safety Law" and its implementation regulations.