Analyzing the Safety Impacts of Variable Speed Limit Control on Aggregated Driving Behavior Based on Traffic Big Data

Table 4

Percentages of smaller than 100 m headway within different density intervals under different speed limits (“—” means less than 300 vehicles are observed).

Lane	Density (veh/km)	Percentage of less than 100-m headway under different speed limits (%)
		No VSL (%)	120 km/h (%)	100 km/h	80 km/h	60 km/h	50 km/h
Left lane	5–10	23	21	15%	—	—	—
	10–15	32	28	19%	17%	—	—
	15–20	35	26	15%	18%	14%	—
	20–25	38	27	18%	23%	28%	24%
	25–30	42	33	33%	38%	42%	—
Middle lane	5–10	9	6	—	—	—	—
	10–15	15	11	8%	—	—	—
	15–20	22	17	13%	17%	—	—
	20–25	28	22	19%	23%	35%	21%
	25–30	34	30	29%	—	—	—
Right lane	5–10	4	4	—	—	—	—
	10–15	9	9	8%	9%	—	—
	15–20	16	18	12%	14%	22%	—
	20–25	29	27	—	—	—	—