Quantification of Rear-End Crash Risk and Analysis of Its Influencing Factors Based on a New Surrogate Safety Measure

Table 2

Summary of independent variables.

Categories	Variables	Conditions
Behavioral variables	Duration of car-following event	Continuous variable (0.1 s)
	Mean time headway	Continuous variable (s)
	Average speed difference	Continuous variable (km/h)
	Acceleration difference ratio	Continuous variable
Temporal variables	Day-of-week	Holiday, workday
	Time-of-day	Off peak, morning peak, evening peak
Environmental variables	Light condition	Daytime, nighttime
	Weather condition	Sunny, rainy
	Traffic density	High, median, low