State Highway Access Manual - Sight Distance Standards

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
Intersection Sight Distance Required (ft)
Two Lanes Crossed
Intersection Sight Distance Required (ft)
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:

  1. 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).
  2. Assumes passenger vehicle for design purposes and level grade +3% maximum.
  3. 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.).
  4. Sight distance measurement must conform to the AASHTO models.
  5. Refer to 10.4 for discussion of sigh distance requirements and any substandard conditions

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