LAC 70:I.1313 – Minimum Design Guidelins for Rural Collector Roads

Item No.	Item	Rural
		RC-1	RC-2	RC-3
1	Average Daily Traffic 1	Under 400	400-2000	Over 2000
2	Design Speed (mph)	40–60²	50–60²	60
3	Number of Lanes	2	2	2–4³
4	Width of Travel Lanes (ft)	11	11–12⁴	12
5	Width of Shoulders (ft)
	(a) Inside on multilane facilities	N/A	N/A	4
	(b) Outside	2⁵	4–5⁶	8
6	Shoulder Type	Paved	Aggregate (2' min paved)	Aggregate (2' min paved)⁷
7	Width of Parking Lanes (ft)	N/A	N/A	N/A
8	Width of Median on multilane facilities (ft)
	(a) Depressed	N/A	N/A	42-60
	(b) Raised	N/A	N/A	N/A
	(c) Two way left turn lane	N/A	N/A	N/A
9	Width of Sidewalk (minimum) (ft)
	(a) Offset from curb	N/A	N/A	N/A
	(b) Adjacent to curb	N/A	N/A	N/A
10	Fore Slope (vertical-horizontal)	1:4	1:4	1:6
11	Back Slope (vertical-horizontal)	1:4⁸	1:4	1:4
12	Pavement Cross Slope (%) 8	2.5	2.5	2.5
13	Stopping Sight Distance (ft)	305 (40 mph) 425 (50 mph) 570 (60 mph)	425 (50 mph) 570 (60 mph)	570
14	Maximum Superelevation (%)⁹	10	10	10
15	Minimum Radius (ft) 10 (with full superelevation)	450¹¹	700¹²	1,100
16	Maximum Grade (%)	7 (40 mph) 6 (50 mph) 5 (60 mph)	6 (50 mph) 5 (60 mph)	5
17	Minimum Vertical Clearance (ft)¹³	15	15	15
18	Minimum Clear Zone (ft) (from edge of through travel lane)	10, 14, 24¹⁴	26 (50 mph) 32 (60 mph)	30
19	Bridge Design Live Load¹⁵	AASHTO	AASHTO	AASHTO
20	Minimum Width of Bridges (face to face of bridge rail at gutter line) (ft)	30	Roadway width	Roadway width

Authority Note

AUTHORITY NOTE: Promulgated in accordance with R.S. 48:35(C).

Historical Note

HISTORICAL NOTE: Promulgated by the Department of Transportation and Development, Office of Highways/Engineering, LR 30:809 (April 2004), repromulgated LR 30:2335 (October 2004), amended LR 35:2844 (December 2009).