sustainability Article Crash- and Simulation-Based Safety Performance Evaluation of Freeway Rest Area Hyeonseo Kim 1 , Kyeongjoo Kwon 2 , Nuri Park 1 , Juneyoung Park 1,2, * and Mohamed Abdel-Aty 3   Citation: Kim, H.; Kwon, K.; Park, N.; Park, J.; Abdel-Aty, M. Crash- and Simulation-Based Safety Performance Evaluation of Freeway Rest Area. Sustainability 2021, 13, 4963. https:// doi.org/10.3390/su13094963 Academic Editor: TamásBányai Received: 5 April 2021 Accepted: 25 April 2021 Published: 28 April 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Smart City Engineering, Hanyang University, Ansan 15588, Korea; pass782@naver.com (H.K.); nuripark@hanyang.ac.kr (N.P.) 2 Department of Transportation and Logistics Engineering, Hanyang University, Ansan 15588, Korea; koy3450@naver.com 3 Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816, USA; M.Aty@ucf.edu * Correspondence: juneyoung@hanyang.ac.kr; Tel.: +82-31-400-5151 Abstract: The main objective of this study was to evaluate the safety effects caused by altering the lengths of deceleration and acceleration lanes at rest areas on expressways in Korea. Although general conclusions can be found through crash-based safety analysis, to examine more specific optimal conditions considering various traffic conditions, this study proposes a novel framework to explore and evaluate crash-based and simulation-based safety performances. For this purpose, the safety performance function (SPF) and crash modification factor (CMF) were developed to reflect real-world safety impacts. To consider nonlinear trends of the parameters, nonlinearizing link functions were introduced into the analysis. Two types of simulation analyses were conducted to (1) find the combination of surrogate safety measures (SSMs) that best fit with the crash-based safety performance results and (2) determine the optimal lengths of deceleration lane and acceleration lanes for different traffic conditions. The results showed that the best length of deceleration lane of a rest area is between 240 and 260 m, depending on the traffic conditions. The results also indicated that the optimal length of acceleration lane of a rest area is between 385 and 400 m, depending on the traffic parameters. The findings of this study could be used to determine the safety solutions with a micro-traffic simulator. Keywords: safety performance; traffic simulation; surrogate safety; rest area; crash modification factor 1. Introduction According to the KoEX (Korea Expressway Corporation) (2019) [1], crashes caused by drowsy driving have a higher death rate than general crashes over a recent 10-year period (2007–2016) in Korea. To reduce drowsy driving crashes, the KoEX began installing rest areas in 2011. Currently, 223 rest areas are operating on expressways in Korea. Rest areas are designed to reduce drowsy driving by providing a resting place for drivers. Based on the KoEX crash data, a total of 128 crashes occurred at rest areas over a five–year period (2012–2016), and 99 of these occurred in the deceleration and acceleration lanes of the rest areas. The main cause of crashes at the entry and exit points was rapid deceleration, resulting in conflicts with mainline driving vehicles. In Korea, according to the rest area design manual (Ministry of Land, Infrastructure and Transport in Korea, 2019) [2], the current lengths of deceleration and acceleration lanes in rest areas are constructed based on a designed speed of 100 km/h. The length of the deceleration lane is 215 m, and the length of the acceleration lane is 370 m. The deceleration lanes (used to enter a rest area) and the acceleration lanes (used to exit a rest area) are based on a designed speed of 40 km/h. Rest areas can be broadly divided into parallel types, in which a transition section exists, and tapered types, in which a transition section does not exist. Korean rest areas are generally based on the parallel type. It should be noted that there are two types of rest facilities in Sustainability 2021, 13, 4963. https://doi.org/10.3390/su13094963 https://www.mdpi.com/journal/sustainability