Intersection Delay in Regionwide Traffic Assignment: Implications of 1994 Update of the Highway Capacity Manual

Abstract

The original 1985 Highway Capacity Manual (HCM85) described widely recognized relationships for traffic delay that could be incorporated into travel forecasts. Applications of the HCM85 procedures demonstrated that such delay relationships were both technically feasible and beneficial. In early 1995, the Transportation Research Board released the 1994 update to the HCM (HCM94), heavily revising the signalized and two-way stop intersection procedures and introducing a detailed all-way stop intersection procedure. These new procedures have the potential to improve the accuracy of forecasts and to make forecasts consistent with other design practices. Implementation of the HCM94 procedures into travel forecasts reveals that fewer adjustments are required to make them work within equilibrium traffic assignments. The two-way stop procedure can be used nearly intact. The signalized intersection procedure, although still requiring some adjustments, allows a greater range of traffic conditions and phasing options. The all-way stop procedure cannot be incorporated into travel forecasts because of its restrictions on allowable volumes and turning movements. Tests of the HCM94 procedures in traffic assignments indicate that they produce noticeably different results (both volumes and link delays) than the original HCM85 procedures. Multiple equilibrium solutions are possible, but the differences between these solutions are small and manageable.

A Bi‐Level Model for Planning Signalized and Uninterrupted Flow Intersections in an Evacuation Network

“…An underestimation of such delays may result in a traffic distribution far from realistic. To provide a reliable travel time calculation and simplify the model formulation, this research first incorporates a generalized Bureau of Public Roads (BPR) function developed by Horowitz (1997) to account for the potential turning delays for a road section link upstream to an uninterrupted flow intersection. On the other hand, if the link's downstream intersection is signalized, we consider incorporating turning delays by adopting a flow‐weighted method.…”

“… In the BPR function, are set to be 0.15 and 4. and are set at 1.0, 1.0, and 0.4 according to Horowitz (1997), respectively; The large enough positive integer and penalization are set to be 10,000 and 1,000, respectively; The mutation probability for both the external module and the internal module is 0.03; The population size for the external module and the internal module is set to be 200 and 300, respectively; The crossover probability for both the external and the internal module is set to be 0.2; The maximal number of generations for the external module and the internal module is set to be 100 and 200, respectively; If the difference between 2 adjacent iterations is lower than 0.1% for 5 continuous iterations, the algorithms for both external and internal module are terminated. …”

“…In the BPR function, are set to be 0.15 and 4. and are set at 1.0, 1.0, and 0.4 according to Horowitz (1997), respectively;…”

Stochastic User Equilibrium Traffic Assignment with Turn‐delays in Intersections

“…For two-lane roads one might consider the in¯uence of the trac in the opposite direction (controlled by the g-parameter) by modifying the BPR-formula as described in Horowitz (1997):…”

Assessing the benefit of improved traveler information: a pseudo-dynamic modeling approach

“…In two papers by Horowitz, a modified version of QRSII (AJH and Associates. Milwaukee, WI) was used to incorporate actuated signal control in a sample network and test the use of the HCM 1994 revisions (27,28). Horowitz concluded that actuated signals added realism to the network.…”