Highway Performance Monitoring System

FHWA > Policy Information > HPMS > HPMS Field Manual > Appendix N: Procedures for Estimating Highway Capacity 
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HPMS Field ManualAppendix N: Procedures for Estimating Highway CapacityRural OneLane CapacityApplicationThese highways, though rare, do exist in HPMS. They include facilities with both oneway and twoway operation. ProcedureOneWay Operation The capacity of these sections should be computed using the procedure for Rural TwoLane Highways, with the following changes:
The resulting capacity is, by definition, a oneway value. TwoWay Operation Onelane highways open to both directions of traffic are extremely rare. For these cases, compute the capacity for oneway operation and divide by 2. Rural ThreeLane Highway CapacityApplicationThese highways have two through lanes in one direction and a single lane in the opposite direction. The through lanes are assumed to cover an extended length and are not auxiliary or truck climbing lanes. (This is consistent with the coding of HPMS data). ProcedureIt is assumed that these highways operate as a multilane undivided facility in the twolane direction and as a single direction of a rural twolane facility in the onelane direction. The twoway capacity (required by HPMS for these facilities) is then the sum of these two separate capacities. The capacity for the twolane direction is computed using the Multilane Highway capacity procedure assuming an undivided crosssection. The capacity for the onelane direction is computed using the procedure for Rural OneLane, OneWay Highways.

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Updated: 08/18/2015 