On two-lane roadways, it is important to provide adequate passing sight distance
for as much of the project length as possible to compensate for missed opportunities
due to oncoming traffic in the passing zone. On roadways where the design hourly
traffic volume exceeds 400, the designer should investigate the effect of available
passing sight distance on highway capacity using procedures outlined in the latest
Transportation Research Board “Highway Capacity Manual” (Ref. 10). If the available
passing sight distance restricts the capacity from meeting the design level of service
requirement, then adjustments should be made to the profile to increase the distance.