Development of safety performance measures for different crashes severity at urban roundabouts

Roundabouts are widely utilized due to their perceived safety benefits compared to other unsignalized intersections. Studies have demonstrated that roundabouts are effective in reducing the frequency and severity of traffic crashes. However, the crash rate at roundabouts in Jordan has increased over...

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Main Authors: Taqwa I. Alhadidi, Mohammad Nour Al-Marafi, Asma Alazimi
Format: Article
Language:English
Published: Elsevier 2025-03-01
Series:Results in Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2590123024019236
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author Taqwa I. Alhadidi
Mohammad Nour Al-Marafi
Asma Alazimi
author_facet Taqwa I. Alhadidi
Mohammad Nour Al-Marafi
Asma Alazimi
author_sort Taqwa I. Alhadidi
collection DOAJ
description Roundabouts are widely utilized due to their perceived safety benefits compared to other unsignalized intersections. Studies have demonstrated that roundabouts are effective in reducing the frequency and severity of traffic crashes. However, the crash rate at roundabouts in Jordan has increased over time. A range of factors can influence the safety performance of roundabouts, including geometric and traffic characteristics. This study aims to quantify the impact of these factors on the safety of urban roundabouts in Amman, the capital of Jordan. To achieve this, three different crash severity prediction models were developed to assess the influence of various contributing factors. Data was collected from 16 roundabouts over a period of seven years, including traffic crashes, geometric characteristics, and traffic counts. Different models were tested, and the Negative Binomial (NB) model was found to be the best fit for traffic crashes frequency. The results indicate that an increase in entry width, inscribed diameter, entry path radius, entry angle, speed limit, number of approaches, weaving length, and weaving width are associated with an increase in roundabout crash risk. On the other hand, an increase in circular width, central diameter, and exit width is associated with a decrease in crash risks. The study also developed Crash Modification Factors (CMFs) using a cross-sectional method, which can be used to investigate the relationship between safety and geometric design features of roundabouts. The findings of this study can be used effectively to determine the appropriate intersection improvement strategies to enhance traffic safety conditions.
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spelling doaj-art-a28cbde3e1884697a6d46a663510034b2025-08-20T02:01:24ZengElsevierResults in Engineering2590-12302025-03-012510368010.1016/j.rineng.2024.103680Development of safety performance measures for different crashes severity at urban roundaboutsTaqwa I. Alhadidi0Mohammad Nour Al-Marafi1Asma Alazimi2Civil Engineering Department, Al-Ahliyya Amman University, Amman, 19328, Jordan; Corresponding author.Department of Civil Engineering, Tafila Technical University, Tafila, JordanDepartment of the Construction Project, Ministry of Public Works of Kuwait, Kuwait City 12011, KuwaitRoundabouts are widely utilized due to their perceived safety benefits compared to other unsignalized intersections. Studies have demonstrated that roundabouts are effective in reducing the frequency and severity of traffic crashes. However, the crash rate at roundabouts in Jordan has increased over time. A range of factors can influence the safety performance of roundabouts, including geometric and traffic characteristics. This study aims to quantify the impact of these factors on the safety of urban roundabouts in Amman, the capital of Jordan. To achieve this, three different crash severity prediction models were developed to assess the influence of various contributing factors. Data was collected from 16 roundabouts over a period of seven years, including traffic crashes, geometric characteristics, and traffic counts. Different models were tested, and the Negative Binomial (NB) model was found to be the best fit for traffic crashes frequency. The results indicate that an increase in entry width, inscribed diameter, entry path radius, entry angle, speed limit, number of approaches, weaving length, and weaving width are associated with an increase in roundabout crash risk. On the other hand, an increase in circular width, central diameter, and exit width is associated with a decrease in crash risks. The study also developed Crash Modification Factors (CMFs) using a cross-sectional method, which can be used to investigate the relationship between safety and geometric design features of roundabouts. The findings of this study can be used effectively to determine the appropriate intersection improvement strategies to enhance traffic safety conditions.http://www.sciencedirect.com/science/article/pii/S2590123024019236Traffic crashesRoad safetyCrash prediction modelCrash modification factorCross-sectional modelAccident severity
spellingShingle Taqwa I. Alhadidi
Mohammad Nour Al-Marafi
Asma Alazimi
Development of safety performance measures for different crashes severity at urban roundabouts
Results in Engineering
Traffic crashes
Road safety
Crash prediction model
Crash modification factor
Cross-sectional model
Accident severity
title Development of safety performance measures for different crashes severity at urban roundabouts
title_full Development of safety performance measures for different crashes severity at urban roundabouts
title_fullStr Development of safety performance measures for different crashes severity at urban roundabouts
title_full_unstemmed Development of safety performance measures for different crashes severity at urban roundabouts
title_short Development of safety performance measures for different crashes severity at urban roundabouts
title_sort development of safety performance measures for different crashes severity at urban roundabouts
topic Traffic crashes
Road safety
Crash prediction model
Crash modification factor
Cross-sectional model
Accident severity
url http://www.sciencedirect.com/science/article/pii/S2590123024019236
work_keys_str_mv AT taqwaialhadidi developmentofsafetyperformancemeasuresfordifferentcrashesseverityaturbanroundabouts
AT mohammadnouralmarafi developmentofsafetyperformancemeasuresfordifferentcrashesseverityaturbanroundabouts
AT asmaalazimi developmentofsafetyperformancemeasuresfordifferentcrashesseverityaturbanroundabouts