Estimation of Traffic Delay Due to U-turns at Uncontrolled Medians: Case Study in Phnom Penh, Cambodia

Maksat Omarov1, *, Syuhaida Ismail2, Wan Nurul Mardiah Wan Mohd Rani3
1 Research Scholar at UTM Razak Faculty of Technology and Informatics, Malaysia
2 Assoc. Professor at UTM Razak Faculty of Technology and Informatics, Malaysia
3 Senior Lecturer at UTM Razak Faculty of Technology and Informatics, Malaysia


Lack of infrastructure capacity to the demand in mobility results in delays in traffic. U-turns restrict the movement of the opposing through traffic during the maneuver, hence triggering delays. Significant delays can be observed especially in high volume traffic where U-turning is not restricted. It is imperative to study the delays incurred by the U-turning vehicles to assess their impact on the traffic congestion. This study proposes a quantitative method to estimate the aggregate and average delay per vehicle caused by U-turns at uncontrolled medians of urban roads. Traffic data was collected at a corridor where vehicles were allowed to U-turn on a four-lane divided mixed traffic urban road in Phnom Penh, Cambodia. The delay in the opposing lane traffic were calculated by analyzing the data using a novel analytical model, a derivative of the Webster's delay model. The results reveal that the suggested technique evaluates the caused delay with good accuracy. Excessive traffic delay and about three seconds delay per vehicle in the opposite through lane traffic aligns well with the experienced delay at the site. The method can be used to assess the delay at straight corridor sections where U-turns are not restricted; understand the causes of the delay; and develop control measures for improved traffic performance.

Keywords: Traffic delay estimation, Congestion, Traffic flow, U-turn, Phnom penh, Cambodia.

Abstract Information

Identifiers and Pagination:

Year: 2021
Volume: 15
Publisher Item Identifier: EA-TOTJ-2021-10

Article History:

Electronic publication date: 29/7/2021
Collection year: 2021

© 2021 Omarov et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: Address correspondence to this author at Research Scholar at UTM Razak Faculty of Technology and Informatics, Malaysia; E-mail: