9.2.6 Stopping Sight Distance

Stopping sight distance for mobility corridors is calculated using Perception-Reaction Distance and Deceleration Distance. The calculated and design distances are shown in
Table 9-1
. Significant changes from level grade may affect deceleration distance. Adjustment factors can be found in
Table 9-2
.
Table 9-1: Mobility Corridor Stopping Sight Distance on Level Grade
Design Speed (mph)
Break Reaction Distance
1
 (ft)
Braking Distance (ft)
Stopping Sight Distance
Calculated (ft)
Design (ft)
85
312.4
693.5
1,005.9
1,010
90
330.8
777.5
1,108.3
1,110
95
349.1
866.21
1,215.3
1,220
100
367.5
959.8
1,327.3
1,330
Notes:
  1. Brake reaction distance predicated on a time of 2.5-s; deceleration rate 11.2-ft/s².
Table 9-2: Adjustment to Braking Distance On Grades
Grade
-4%
-3%
-2%
-1%
1%
2%
3%
4%
Adjustment
1.130
1.094
1.061
1.030
0.972
0.946
0.921
0.897