Speed Limit
(mph)
|
Sight Distance
(feet)
| |
20
|
115
| |
25
|
155
| |
30
|
200
| |
35
|
250
| |
40
|
305
| |
45
|
360
| |
50
|
425
| |
55
|
495
|
Road Classification
| |||||
---|---|---|---|---|---|
Item
|
Minor
|
Local
|
Collector
| ||
Average daily traffic (ADT)
|
1 to 80
|
81 to 480
|
over 480
| ||
Minimum width of right-of-way (feet)
|
50
|
60
|
66
| ||
Minimum roadway width (feet)
|
22
|
22
|
24
| ||
Minimum pavement width (if paved) (feet)
|
18
|
18
|
20
| ||
Minimum width of shoulders on paved roads (feet)
|
2
|
2
|
2
| ||
Maximum grade (slope)
|
12%
|
12%
|
10%
| ||
(Exception to this grade for distance of 300
feet or less)
|
18%
|
15%
|
12%
| ||
Minimum center-line radii on curves (feet)
|
100
|
150
|
200
| ||
Minimum tangent length between reverse curves
(feet)
|
100
|
150
|
200
| ||
Minimum angle of intersections
|
60º
|
60º
|
60º
| ||
Minimum distance between road intersections
(feet)
| |||||
Same side
|
N/A
|
300
|
400
| ||
Opposite side
|
N/A
|
150
|
250
| ||
Maximum grade within 75 feet of intersection
(measured from edge of roadway)
|
5%
|
4%
|
3%
| ||
Maximum grade of cul-de-sac, dead end, or back-around
|
5%
|
4%
|
3%
| ||
Minimum curb radii (or edge roadway) (feet)
| |||||
60º to 86º intersections
|
25
|
25
|
30
| ||
87º to 94º intersections
|
15
|
20
|
20
| ||
95º to 120º intersections
|
30
|
40
|
40
| ||
Minimum property line radii at intersections
(optional chords allowed) (feet)
|
10
|
15
|
20
| ||
Dead-end streets
|
(See Standard Detail No. 1)[1]
| ||||
Cul-de-sac turnaround radii (minimum) (feet)
| |||||
|
Property line
|
55
|
60
|
N/A
| |
Outside of roadway
|
45
|
50
|
N/A
| ||
Back-around
|
(See Standard Detail No. 2)[2]
| ||||
Road base (total minimum) (inches)
|
14
|
14
|
18
| ||
Subbase material
|
12
|
12
|
12
| ||
Base course or surface material
|
2
|
2
|
6
| ||
Road crown
|
3%
|
3%
|
2%
| ||
Maximum superelevation rate
|
10%
|
10%
|
8%
| ||
Minimum sight distance at intersection
|
10 feet for each 1 mph of posted speed (example:
for a posted speed of 35 mph, sight distance shall equal 350 feet
in both directions)
| ||||
Minimum culvert size (inches)
| |||||
Driveways
|
12
|
12
|
15
| ||
All other
|
12
|
15
|
15
| ||
Side slopes
| |||||
Cut
|
2:1
|
2:1
|
3:1
| ||
Fill
|
3:1
|
3:1
|
4:1
| ||
Minimum overhead clearance (feet)
|
15
|
15
|
15
| ||
Minimum "K" value1 for vertical curves
| |||||
Crest
|
24
|
28
|
55
| ||
Sag
|
30
|
35
|
55
| ||
Minimum length of vertical curve (feet)
|
100
|
150
|
200
|
NOTES:
1 "K" value is a
coefficient by which the algebraic difference in grades must be multiplied
to determine the minimum length (in feet) of the connecting vertical
curve.
|
W = 573/R
| |
Where:
| |
W = extra widening (feet)
| |
R = center-line radius (feet)
|
Percentage by Weight Passing Sieve
| |||
---|---|---|---|
Sieve
|
Gravel
|
Sand
| |
1/4 inch
|
25 to 75
|
60 to 100
| |
No. 40
|
5 to 30
|
0 to 50
| |
No. 200
|
0 to 5
|
0 to 7
|
Percentage by Weight Passing Sieve
| |||
---|---|---|---|
Sieve
|
Screened
|
Crushed
| |
1/2 inch
|
35 to 75
|
45 to 70
| |
1/4 inch
|
25 to 60
|
30 to 55
| |
No. 40
|
5 to 25
|
5 to 20
| |
No. 200
|
0 to 5
|
0 to 5
|
Speed Limit
(mph)
|
Sight Distance
(feet)
| |
20
|
115
| |
25
|
155
| |
30
|
200
| |
35
|
250
| |
40
|
305
| |
45
|
360
| |
50
|
425
| |
55
|
495
|