Two Stop-Line Method for Modern T-Shape Roundabout: Evaluation of Capacity and Optimal Signal Cycle

Table 1

Notations’ variables used in this article.

Notations	Description	Units
	Origin or centre of the roundabout
	Angle between two radian points
	Angle between two radian points of auxiliary queuing lane
	Limited vehicles queue before second stop-line from approach x	m
	Radius of the roundabout	m
	No. of possible vehicle’s queue on the approach x	m
	Average occupied space of a single vehicle	m
	Left-turning lanes in circulatory roadway for the approach x vehicles	m
	No. of vehicles
	Capacity of circulatory roadway for left-turn vehicles	Pcu/h
	Weaving width of circulatory roadways	m
	Entry lane
	Exit lane
	Signal cycle length	s
	Total lost time	s
	Total no. of phases j to k for approach x	s
	Saturation flow towards circulatory roadway by using phase j	Pcu/h
	Lost time during signal cycle	s
	Total lost time of red light during change cycle	s
	Time to leave vehicle before second stop line (SL) from approach x	s
	Saturation flow of circulatory roadway	Pcu/h
	Effective green total time per cycle	s
	Effective green time for approach 1	s
	Effective green time for approach 2	s
	Effective green time for approach 3	s
	Saturation flow rate of straight-going traffic at approach x	Pcu/h
	Traffic flow rate of approach x	Pcu/h
	Green time adjustment of straight-go flow of approach (2, 3)	s
	Saturation flow rate of straight-go traffic of approach x	Pcu/h
	Width of one circulatory lane of roundabout	m
	Green time for straight-go traffic on approach x	s
	Left-turn vehicle ratio from approach x	Pcu/h
	Saturation flow rate for left-turn vehicles on approach x	Pcu/h
	Limited no. of lanes for left-turn vehicles
	Saturation flow of left-turn lane on approach x	Pcu/h
	Green time for left-turn flow before second stop line	s
	Changing interval between and	s
	Capacity of one approach direction	Pcu/h
	Total capacity of TLSR-2SL	Pcu/h
	Capacity of first stop-line from approach x	Pcu/h
	Capacity of second SL from approach x	Pcu/h
	No. of straight-going lanes at first SL on approach x
	Green time for first SL vehicles at approach x	s
	Capacity of left-turn vehicles on approach x at first stop-line	Pcu/h
	Green time of left-turn vehicles at first SL on approach x	s
	No. of left-turn lanes at first SL on approach x
	Left-turn flow inside circulatory from approach x	Pcu/h