Investigation on Two-Stop-Line Signalized Roundabout: Capacity and Optimal Cycle Length

Table 1

Variable notations in this research.

Variable notations	Description	Unit
	Capacity of one through lane at the 1st stop line	pcu/h
	Capacity of one left-turn lane at the 1st stop line	pcu/h
	Capacity of one left-turn lane at the 2nd stop line	pcu/h
	Overall capacity of one left-turn lane	pcu/h
	Overall capacity of one direction approach	pcu/h
	Saturation flow of one through lane at the 1st stop line	pcu/h
	Saturation flow of one left-turn lane at the 1st stop line	pcu/h
	Effective green time for through traffic flow	s
	Effective green time for left-turn traffic flow at 1st stop line	s
	Cycle length of the traffic signal	s
	Optimal cycle length of the traffic signal	s
	Vehicle-storage capacity of and part of queueing area	pcu
	Number of circulatory lanes assigned to left-turn traffic flow during phase P-2
	Total number of circulatory lanes excluding right-turn lane
	Radian of the 1st part of queuing area	rad
	Radian of the 2nd part of queuing area	rad
	Radius of the central island	m
	Radius of circulatory lane	m
	Average parking space for a vehicle, normally is 6	m
	Traffic volume of lane	pcu/h
	Average traffic delay of lane	s