Chapter 6 - Cross Section Elements

6.5. Curbs – Outside Shoulders

The type and location of curbs affects driver behavior and the safety and utility of a highway. Curbs serve any or all of the following purposes:

• drainage control

• pavement edge delineation

• right-of-way reduction

• aesthetics

• delineation of pedestrian walkways

• reduction of maintenance operations

• assistance in orderly roadside development

 

In the interest of safety, curbs should not be used on rural highways if these objectives can be attained by other means. Sloped curbs may be used in rural areas with posted speeds greater than 45 mph if right-of-way and/or environmental impacts can be minimized or drainage issues need to be addressed.

Sloped curbs on outside shoulders should be located a minimum distance of 10-ft. from the edge of outside travel lane or back of useable shoulder as required by the AASHTO Green Book (2004). Curbs on inside shoulders shall be offset at least 4-ft. from the inside edge of travel lane to face of curb.

Curbs may be constructed by a variety of methods. Typical shapes and dimensions for various types of curbs, including curb and gutter, are shown in GDOT Construction Standards and Details Ga. Std. 9032B.

 

Table 6.7. Curb Types Allowed for Various Types Of Roads
Curb Type(1)	Road Type
	Interstate	Urban Type A	Urban Type B	State Route Design Speed < 45 mph	State Route Design Speed > 45 mph	Other Off Roadway Classification
Concrete Curb and Gutter
Type 1						x
Type 2		x	x	x		x
Type 3						x
Type 4						x
Type 7		x	x	x	x	x
Concrete Header Curb
Type 1						x
Type 2		x	x	x		x
Type 3						x
Type 4						x
Type 7		x	x	x	x	x
Type 8		x	x	x	x
Raised Median
Type 1
Type 2				x
Type 7	x	x	x	x	x
Raised Island
Type 1
Type 2				x
Type 7		x	x	x	x
V Gutter	x	x	x
(1) Typical shapes and dimensions for various types of curbs, including curb and gutter, are shown in Ga. Std. 9032B. Four-inch sloped Type I curbs placed at the back of the usable shoulder may be used on high speed facilities.