01660313

Component

Freeway merges are typical congestion areas because of the irregularities on lanes between upstream and downstream directions. Generally urban freeways suffer from the interaction between upstream and on-ramp flows that cause a congestion as a result of high demand. The aim of this study is to analyze this interaction and determine the variation of upstream and on-ramp flows at capacity level in İstanbul freeway merges where the ramp metering application is not present.In order to clarify the macroscopic merging behavior, three freeway merges without ramp-metering operation are investigated where a variety of number of lanes at upstream and downstream is present.The presence of initial congestion on merge section is determined by means oftime-speed and rescaled cumulative flow diagrams. It is found that an inverse relationship is present between the upstream and the on-ramp flows at downstream capacity level, the increase of the on-ramp flow is smaller than the decrease of upstream flow. In other word the increase of on-ramps flow decrease the sum of upstream and on-ramp flows. At the capacity level when the upstream flow is four times greater than the on-ramp flow per lane, the lane capacity is determined as 2137 pcu/h; however, this number drops to 1732 pcu/h when the upstream flow is twice the on-ramp flow, and 1316 when the upstream and on-ramp flows are equal to each other. Lane capacities numbers must be multiplied by the number of lanes to determine the upstream and on-ramp capacities.

This paper was sponsored by TRB committee AHB20 Standing Committee on Freeway Operations.

18-04881

English

13p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; References

Expressways; Highway capacity; Merging traffic; On ramps

Istanbul (Turkey)

Highways; Operations and Traffic Management

Transportation Research Board Annual Meeting 2018 Paper #18-04881

TRIS, TRB, ATRI

Jan 8 2018 11:12AM