Chapter 6 - Cross Section Elements

6.2. Typical Section Geometrics

6.2.1. Lane Width

GDOT's standard for lane widths is 12-ft., except as noted in Table 6.5. The values presented in Table 6.5. represent typical values used by GDOT and are not a complete list of all lane and shoulder widths used.

Click here for a full page view of Table 6.5. Typical Lane and Shoulder Widths

Table 6.5. Typical Lane and Shoulder Widths(1)
Lane Type	Lane Width (ft)	Inside Shoulder (ft) No Curb and Gutter			Outside Shoulder (ft) No Curb and Gutter		Outside Shoulder With Curb and Gutter (ft)
		Overall(2)		Paved	Overall(2)	Paved
Arterial or Collector	12	6		2	10	6.5	16
Urban Type A	11						16
Urban Type B	12
Local Roads (if ADT<400, refer to AASHTO Green Book)	12	6		2	10	6.5
Shared Bike Routes	14
Designated Bike Routes	4
Channelized Turn Lane	16 (min.)
HOV	14
Two Way Left Turn Lane (TWLTL)	14
TWLTL with provision for future 20-ft.raised median	14	See special details for other roadway dimensions
One-Way Roadway, Single Lane	16
One-Way Roadway, Multilane	12
Loop Ramp
Free Flow Ramps
Single Lane Entrance/Exit Ramps	16	6	4		12	10
Multi Lane Entrance/Exit Ramps	12	6	4		12	10
Interstates & Freeways	12	Refer to the current AASHTO publication,   A Policy on Design Standards -- Interstate System
Notes: (1) The need for additional widening shall be determined in accordance with AASHTO recommendations. (2) Overall shoulder width does not include additional width required for the installation of barrier.

 

In applying these lane width guidelines, two applications are defined; the confined, restricted right-of-way urban area, “Urban Area Type A” and the less confined “Urban Area Type B”. Generally, no single defining criteria, such as speed limit or functional classification, determines lane widths. Instead, a combination of characteristics define the applicable areas.

The characteristics below are representative of and define urban area types, and, in turn, determine the minimum allowable lane width:

Urban Area Type A  

• speed limit 35 mph or less
• curb and sidewalk
• central business district (CBD) / historic districts / overlay streetscape
• zoning /corridor continuity characteristics
• building face to curb typically less than 10-ft.
• low percentage of trucks
• lane widths may be reduced to no less than 11-ft.

Urban Area Type B

• speed limit greater than 35 mph but not greater than 45 mph
• curb and sidewalk
• less confined, less urbanized area, generally automobile dependent, numerous driveways
• building face to curb typically less than10-ft.
• lane widths shall be 12-ft.; design variances will be required for lane width reductions

The standard pavement cross-slope adopted by GDOT for travel lanes is 2% (0.020 ft/ft). Roadways with three or more lanes should break the cross-slope between lane 2 and lane 3 from 2% to 3% (lanes are numbered from inside to outside).