8.1.2 Target Design Values

Table 8-1

shows target design values of Freeways for each context classification. These design values may be adjusted based on the anticipated target speed and a performance-based practical design evaluation of the corridor as discussed in

Chapter 2

The subsections following

Table 8-1

provide additional detailed discussions for each design element and factors that may influence these values.

The design value thresholds for design exceptions and design waivers are presented in
Appendix A
and
Appendix B
respectively.

Table 8-1: Target Design Values for Freeway Mainlanes
Design Element			Rural	Suburban	Urban	Urban Core	Reference
Roadway		Design Speed¹	75 MPH	70 MPH	65 MPH	60 MPH	See 8.1.3
		Lane Width	12-ft				See 8.1.6
		Inside Shoulder Width (4-Lane Divided)	8-ft				See 8.1.7
		Inside Shoulder Width (6-Lane or More Divided)	12-ft				See 8.1.7
		Outside Shoulder Width	12-ft				See 8.1.7
		Speed Change Lane - Lane Width - Shoulder Width	12-ft 10-ft				See 8.1.8 See 8.1.8
		Median Width	Varies				See 4.10.15 and 8.1.9
		Horizontal Curve Radius (Minimum)	See 4.7
		Cross Slope on a Tangent (Typical)	2%				See 4.10.4
		Cross Slope on a Tangent (Maximum)	3%				See 4.10.4
		Superelevation Rate (Maximum)	See Table 4-3, Table 4-6, and Table 4-7				See 4.7.3
		Minimum Grade	0.25% (lined ditch channels), 0.3% (curbed facilities), or 0.5% (unpaved ditches)				See 4.8.1
		Maximum Grade (Level)	3%				See 4.8.1
		Maximum Grade (Rolling)	4%				See 4.8.1
		Vertical Clearance	18.5-ft				See 4.8.6, and 21.2
		Design Loading Structural Capacity	HL-93				See 8.1.14
		Stopping Sight Distance	See 4.11.1
		Design Vehicle	WB-67				See 4.3.2
		Level of Service (LOS Design Year)	B	C	C	C	See 8.1.5
Roadside		Clear Zone	See Table 4-20				See 4.10.7
Roadside		Outer Separation	Varies				See 8.1.17
Notes		Denotes that this is a design exception condition if the specified values in Appendix A are not met.
		Denotes that this is a design waiver condition if the specified values in Appendix B are not met.
	1.	The selected Design Speed should meet the anticipated target speed of the facility during non-peak hours.

8.1 Design Considerations