Calculating the Contribution Rate of Intelligent Transportation System in Improving Urban Traffic Smooth Based on Advanced DID Model

Table 2

Main impact indicators of traffic smooth.

Category	Indicator contents	Relevance to the smooth
The social economic	Population; GDP	Negative correlation
Traffic demand	Motor vehicle ownership; Civilian car ownership	Negative correlation
Traffic supply	Road mileage, road area	Positive correlation
	Public vehicle number	Positive correlation
	Public transportation passenger	Positive correlation