7.1.2 Target Design Values

Table 7-1

shows target design values for Arterials 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 (see

Chapter 2

The subsections following

Table 7-1

provide additional discussion for each design element and factors influencing these values.

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

Table 7-1: Target Design Values for Arterials
Design Element			Rural	Rural Town	Suburban	Urban	Urban Core	Reference
Roadway		Design Speed¹	70 MPH	40 to 45 MPH	50 to 60 MPH	40 to 45 MPH	30 to 35 MPH	See 7.1.3
		Travel Lane Width	12-ft	11 to 12-ft	12-ft	11-ft	11-ft	See 7.1.6
		Shoulder Width (Uncurbed)²	10-ft²	4 to 10-ft²	8 to 10-ft²	4 to 10-ft²	4 to 10-ft²	See 7.1.7
		Offset to Face of Curb	2-ft					See 4.10.12
		Curb Parking Lane Width⁵	N/A	10-ft	N/A	10-ft	10-ft	See 4.10.16
		On-Street Bike Lane Width	N/A	5-ft	5-ft	5-ft	5-ft	See 18.4.5
		Speed Change Lane Width	12-ft	12-ft	12-ft	11-ft	11-ft	See 4.10.2
		Median Width	See 4.10.15
		Horizontal Curve Radius	See 4.7
		Cross Slope on a Tangent	2%					See 4.10.4
		Cross Slope on a Tangent (Maximum)	3%					See 4.10.4
		Superelevation Rate	See Table 4-3 through 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%	6%	5%	6%	8%	See 4.8.1
		Maximum Grade (Rolling)	4%	7%	6%	7%	9%	See 4.8.1
		Vertical Clearance at New Structures³	18.5-ft³					See 4.8.6
		Design Loading Structural Capacity	HL-93					AASHTO LRFD Bridge Design Specs
		Stopping Sight Distance (SSD)	See 4.11.1
		Design Vehicle⁴	WB-67	WB-67	WB-67	SU-40⁴	SU-40⁴	See 4.3.2
		Level of Service (LOS Design Year)	B	B	B	B	C	See 4.3.4.1
Roadside		Clear Zone (Curbed)	See 4.10.7
		Clear Zone (Uncurbed)	See 4.10.7
		Sidewalk Width	5-ft (if applicable)	5-ft	5-ft	6 to 8-ft	5 to 8-ft	See 19.3.2
		Sidewalk Offset	N/A	Varies 6-ft or more for curbed roadways Clear Zone width or more for uncurbed roadways				See 19.3.2
		Border Width	N/A	20-ft	20-ft	20-ft	15-ft	See 4.10.9
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.
	2	A 12-ft paved shoulder should be considered where the volume of truck traffic exceeds 250 DDHV. An 8-ft minimum paved shoulder should be considered for truck traffic volumes that are less than 250 and the highway is located on the Texas Highway Freight Network (THFN).
	3	A 16.5-ft vertical clearance may be used if the highway is not on the Texas Highway Freight Network (THFN). Specific railroad company guidelines may require additional vertical clearance requirements.
	4	Consider providing intersection turning radii for a WB-67 design vehicle on roadways or streets that are located on the Texas Freight Network and when high (>10%) truck turning movements are known or expected.
	5	If a bike lane is adjacent to a parking lane, the parking lane width should be increased to 12-ft to allow car doors to be open without bicyclist conflict. See Section 4.10 for additional guidance.

7.1 Design Considerations