| Appendix G: Highway Design Reference |
SIGHT DISTANCE STANDARDS
(Applies to Full Movement Access on Undivided Highways)
|
Actual Posted Speed (mph)
|
Assumed Design Speed(mph)
|
Stopping Sight Distance Required (ft)
|
Intersection Sight Distance Required (ft)
|
|
One Lane Crossed
|
Two Lanes Crossed
|
Three Lanes Crossed
|
|
30
|
40
|
305
|
445
|
475
|
500
|
|
35
|
45
|
360
|
500
|
530
|
565
|
|
40
|
50
|
425
|
555
|
590
|
625
|
|
45
|
55
|
495
|
610
|
650
|
690
|
|
50
|
60
|
570
|
665
|
710
|
750
|
|
55
|
65
|
645
|
720
|
765
|
815
|
Notes:
- Values and methodology based on A Policy on Geometric Design of Highways and Streets, AASHTO, 2001 for the design speeds shown. Intersection sight distance values shown are governed by the left turn movement from the access point onto the state highway (Case B1, p.660).
- Assumes passenger vehicle for design purposes and level grade +3% maximum.
- Refer to the AASHTO guidelines to address different conditions (e.g. access limited to specific turning movements, more than two opposing lanes of traffic to be crossed, steep grade, median crossover, other design vehicles, etc.).
- Sight distance measurement must conform to the AASHTO models.
- Refer to 10.4 for discussion of sigh distance requirements and any substandard conditions
|
|
