01594109

Component

This paper presents a simple method to develop the capacity distribution of a freeway bottleneck from field sensor observations. The approach clearly distinguishes between capacity, a spatial attribute of the bottleneck geometry and period of observation and the observed pre-breakdown flow rate, which tends to be correlated with the configuration of the traffic volume profile level over time. The estimated capacity distribution is shown to be independent of time of day. The relationship between the true capacity distribution and pre-breakdown flow rate distribution is best characterized by a non-homogeneous geometric distribution. By testing the hypothesis on several real world facilities, the proposed relationship is demonstrated, and a parameter defined as the ‘Acceptable Breakdown Rate’ is used to extract a single capacity value from the distribution. All flow rates are aggregated in 15 minute intervals. For Highway Capacity Manual analysis purposes, a breakdown rate of 15% is proposed, although the method is not bound by a single acceptable value. By applying the acceptable breakdown rate estimation method on four real world facilities in three states, capacity values that varied between 1900 to 2200 pc/h/lane were estimated. The findings of this research are proposed for incorporation in the Highway Capacity Manual 2010 update.

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

01584066

16-5813

English

17p

2016

Transportation Research Board 95th Annual Meeting

Digital/other

Figures; References; Tables

Bottlenecks; Distributions (Statistics); Estimating; Freeways; Highway capacity; Methodology; Periods of the day; Sensors; Traffic flow rate; Traffic volume

Highway Capacity Manual

Highways; Operations and Traffic Management; Planning and Forecasting

Transportation Research Board Annual Meeting 2016 Paper #16-5813

TRIS, TRB, ATRI

Jan 12 2016 6:33PM