9.2.8 Horizontal Alignment

Table 9-4
shows the maximum allowable side friction factors and assumed running speeds for design speeds from 85-mph to 100-mph. The maximum side friction force is only realized at full superelevation and should be avoided unless conditions where limited space places constraints on the horizontal geometry allow no other options. These maximum side forces may be allowed for temporary traffic control during construction or maintenance.
Table 9-4: Mobility Corridor Side Friction Factors and Running Speeds for Horizontal Curves
Design Speed (mph)
Maximum Allowable Friction Factor
Assumed Running Speed (mph)
85
0.07
67
90
0.06
70
95
0.05
75
1
100
0.04
82
1
Notes:
  1. Values adjusted up to accommodate application of AASHTO Method 5 calculations.