Discharge flow rate change under rainy conditions on urban motorways

Göker Aksoy*, Kemal Selçuk Öğüt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Queue discharge flow is the most frequently observed phenomenon on urban motorways when demand exceeds capacity. Once a queue is formed, congestion arises, and the number of vehicles that can pass from downstream reduces. This reduction phenomenon is defined as the capacity drop and calculated by taking the difference between capacity and discharge flow at a road section. Obviously, this capacity drop exists after an onset of congestion and may increase in relation to weather conditions, such as rain, snow, or fog, which cause longer queues and delays. In this paper, the effect of rain on discharge flows is investigated and compared with sunny days on Istanbul urban motorways. Besides, rain precipitation during congestion is considered and related to discharge flow. Four different motorway sections were analyzed, and up to 37% discharge flow reduction was determined between sunny and rainy conditions. Motorway sections with higher free flow speed (FFS) were found to be more affected by rain, and discharge flow reduction was bigger compared to the section with the lowest FFS. For 1 mm/m2/h of precipitation, the discharge flow is estimated as 1,719 pcu/h/lane when FFS is 84 km/h, and as 1,560 pcu/h/lane if FFS is 104 km/h.

Translated title of the contributionKent içi otoyollarda kuyruk dağilma akiminin yağmur etkisi altinda değişimi
Original languageEnglish
Pages (from-to)733-744
Number of pages12
JournalPromet - Traffic and Transportation
Volume30
Issue number6
DOIs
Publication statusPublished - Dec 2018

Bibliographical note

Publisher Copyright:
© 2018, Faculty of Transport and Traffic Engineering. All rights reserved.

Keywords

  • Capacity drop
  • Discharge flow
  • Motorway
  • Rain effect

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