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
|