01555653

Component

Chapters 17, 18, and 22 of the 2010 Highway Capacity Manual (HCM) contain computational procedures for evaluating operational efficiency of signalized intersections, urban street segments, and interchange ramp terminals. These procedures are implemented within several commercial software packages, and likely used by thousands of engineers and planners across the U.S. There has been interest in integrating these computational procedures, because they all require detailed signalized intersection analysis. This integration has presented various challenges, including the treatment of right turns on red (RTOR). The signalized intersection procedures require advance knowledge (or estimation) of RTOR vehicles per time period. Subsequently, RTOR’s are automatically subtracted from right-turn volumes, before executing the full procedure. Although the signalized intersection procedures continue to support this treatment of RTOR, the urban streets and ramp terminals procedures lose accuracy when this occurs. Flow profiles and flow balancing should properly address RTOR to allow accurate computation of vehicle proportions arriving on green, and downstream analysis volumes respectively. This paper highlights urban streets procedure deficiencies, and proposes seven improvements. The changes in flow profiles, and comparisons to micro-simulation results, provide evidence of improved accuracy. Two improvements relate to including major-street and minor-street RTOR in the flow balancing process, two more improvements involve computing base and adjusted RTOR maximum flow rate, and the last three improvements create discharge flow profile logic for three types of RTOR (i.e. permissive, shielded, and free). Four improvements may someday be superseded by explicit RTOR modeling, but the last three should be permanent.

This paper was sponsored by TRB committee AHB40 Highway Capacity and Quality of Service.

01550057

15-1365

English

17p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; References; Tables

Accuracy; Interchange ramps; Methodology; Right turn on red; Signalized intersections; Traffic flow rate

Highway Capacity Manual 2010

Data and Information Technology; Highways; Operations and Traffic Management; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2015 Paper #15-1365

TRIS, TRB, ATRI

Dec 30 2014 12:31PM