A surrogate safety analysis at sharp gore areas of diverging freeway ramps using micro simulation under congested traffic conditions

Abdulaziz H Alshehri; Muhammad Umer Farooq; Abdul Farhan; Ahmed M Yosri; Fayez Alanazi; Ahmed Farouk Deifallah; Mohamed Ahmed Okail

doi:10.1038/s41598-023-49728-4

A surrogate safety analysis at sharp gore areas of diverging freeway ramps using micro simulation under congested traffic conditions

Sci Rep. 2023 Dec 18;13(1):22465. doi: 10.1038/s41598-023-49728-4.

Authors

Abdulaziz H Alshehri¹, Muhammad Umer Farooq², Abdul Farhan², Ahmed M Yosri^{3

4}, Fayez Alanazi⁵, Ahmed Farouk Deifallah⁶, Mohamed Ahmed Okail⁷

Affiliations

¹ Department of Civil Engineering, College of Engineering, Najran University, 66446, Najran, Saudi Arabia.
² Civil and Environmental Engineering Department, University of Nebraska - Lincoln, Lincoln, USA.
³ Civil Engineering Department, Delta University for Science and Technology, Belkas, Egypt. amyosri@ju.edu.sa.
⁴ Civil Engineering Department, College of Engineering, Jouf University, Sakakah, Saudi Arabia. amyosri@ju.edu.sa.
⁵ Civil Engineering Department, College of Engineering, Jouf University, Sakakah, Saudi Arabia. fkalanazi@ju.edu.sa.
⁶ Structural Engineering and Construction Managment Department, Future University in Egypt, New Cairo, 11835, Egypt.
⁷ Faculty of Engineering and Technology, Badr University in Cairo (BUC), Cairo, 11829, Egypt.

Abstract

Safety at the gore areas near diverging ramps is very crucial during planning and implementation of highway safety improvement programs. Limited research has been conducted on safety at the gore areas on arterial roads. This study aims at investigating the impact of improving a sharp gore area in Lincoln, Nebraska by performing a micro simulation before-and-after study with respect to its underlying state of safety and congestion. Data on travel times and traffic volumes for peak hours are incorporated after successful calibration to find out how a geometric intervention can decrease mobility issues as well as the likelihood of crash involvement. This study has utilized VISSIM software package to run the simulation however, to perform safety analysis, Surrogate Safety Assessment Model (SSAM) is used which is developed by the Federal Highway Administration (FHWA). During the model calibration, custom driving behaviors are created to represent driving tendencies of familiar drivers. The simulation results indicated that by adding an auxiliary lane near the gore area, the mobility issues such as bottle necks, lane changing dilemmas and queue lengths are substantially decreased. However, geometric interventions such as provision of a separate lane, increasing ramp spacing, nose spacing, deceleration area and queue storage area considerably reduced the likelihood of rear-end and lane changing crashes. Surrogate safety assessment in diverging ramps, particularly for sharp gores, has not previously been studied, and this study can serve as a primary footmark for future research on ramp-gores safety.