Safety evaluation of design alternatives to separate freeway-opposing traffic

Figures & data

Figure 1. (a) Hazard-free median in Illinois, USA, (b) Cable barrier installed on one side of a hazard-free median in Illinois, USA, and (c) W-beam guardrail installed on both sides of a hazard-populated median in the UAE.

Table 1. Fourteen design alternatives to separate freeway-opposing traffic.

Barrier type	Design description
None	Narrow/wide (Figure 1a) hazard-free median
	Narrow/wide hazard-populated median
TL-3 low-tension (LT) cable	In the middle of a narrow/wide hazard-free median
	On both sides of a wide, hazard-populated median
TL-3 high-tension (HT) cable	Only on one side of a narrow/wide (Figure 1b) hazard-free median
TL-3 w-beam (WB) guardrail	On both sides of a narrow/wide hazard-free median
	On both sides of a narrow (Figure 1c)/wide hazard-populated median
TL-4 concrete	No median separation. Concrete barrier separates opposing traffic

Table 2. Traffic, road, and roadside attributes used to build the modeled road scenarios.

Category	Attribute	Unit	Baseline value(s)
Traffic	Average Annual Daily Traffic (AADT)	Vehicles/Day	135,329
	Traffic Growth Factor	%	4
	Percent of Trucks		10
	Percent of Traffic in Primary Direction		50
Road	Posted Speed Limit	Km/h	120
	Total Number of Lanes	Unit	6
	Lane Width	Meters	3.6
Roadside	Left Shoulder Width	Meters	3
	Median Width		10, 20