01127080

Component

Current methods in the Highway Capacity Manual and SYNCHRO for intersections downstream from congested signalized intersections call for the analyst to apply expected reductions in the per-cycle traffic variance (I-factor) and 95th percentile traffic for each individual turn movement. These reductions imply reductions to the delay and the 95th percentile queue values for the affected turn movement. This study compares the current application of I-factors and 95th percentile traffic with theoretical analyses and with a formulation derived from the Dirichlet random distribution. For testing, per-cycle count data was collected for the variance and 95th percentile traffic. Testing of this data shows that no reduction in either the per-cycle variance or 95th percentile traffic is warranted for the analysis of turn movements that are less than a majority of the total approach traffic. The analysis implies that only limited reductions apply to the largest turn movement. Suggestions for application are presented.

01120148

09-0417

English

14p

2009

Transportation Research Board 88th Annual Meeting

DVD

Figures (1) ; References (6) ; Tables (3)

Data collection; Highway capacity; Operations; Signalized intersections; Traffic congestion; Traffic data; Traffic simulation

Highway Capacity Manual

95th percentile speed; Downstream traffic

Highways; Operations and Traffic Management; I73: Traffic Control

Transportation Research Board Annual Meeting 2009 Paper #09-0417

TRIS, TRB

Jan 30 2009 4:41PM