Methodology for the prioritization of environmental sensor station installation (case study of South Korea) Choong Heon Yang a,n , Amelia C. Regan b a Highway & Transportation ResearchDivision, KoreaInstitute of Construction & Technology, 2311 Deahwa-Dong, Ilsan-Gu, Goyang-Si, Gyenggi-Do 411-712, Republic of Korea b Department of Computer Science and Institute of Transportation Systems Engineering, University of California, Irvine, 4068 Bren Hall, Irvine, CA 92627, USA article info Keywords: Road weather information system (RWIS) Environmental sensor station (ESS) Analytical hierarchy process (AHP) Automated weather station (AWS) Snow removal abstract A road weather information system is increasingly recognized as a critical proactive tool for winter maintenance because of recent unexpectedly heavy snowfalls and continuously colder temperatures in Korea. Therefore, effective operation of this system is a high priority. Environmental sensor stations are important components in such systems. However, resources do not permit the installation of an unlimited number of these sensor stations so some method of site prioritization must be implemented. To date however, no explicit method has been adopted. Therefore, this study proposes a decision support methodology to enable the prioritization of installation of new environmental sensor stations and then demonstrates the effectiveness of the methodology by applying it to road sections in South Korea which are especially vulnerable to snow. The primary feature of this methodology is that it provides a rational ranking for prioritizing these installations. This method can readily be applied to other geographic locations. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction Adverse weather such as temperatures cold enough to cause road freezing and unexpected heavy snowfall significantly impacts the safety and traffic flow of transportation systems. Even though these cannot be perfectly prepared for, resulting damage can be dramatically reduced through interventions involving technologies and public policies. A road weather information system (RWIS) is a network of meteorological and pavement sensors located along the roadway system, used to monitor and then minimize damage caused by harsh weather conditions (Boselly and Doore, 1993; FHWA, 2004). A RWIS consists of many environmental sensor stations (ESS) which are connected to a traffic management center as shown in Fig. 1. ESSs are generally installed at strategic locations to provide accurate real- time road weather information and critical observations for weather forecasts (FHWA, 2005,2008). Unfortunately, no specific policy or guideline for the prioritization of ESS installation has been developed. Therefore, this study proposes a methodology for prioritizing ESS locations so that a limited budget can yield the most useful results. In South Korea, the application of RWIS is still in its infancy. This is because road agencies did not earlier recognize the significance of practical use of road weather information, and resources for develop- ing such systems were insufficient. However, during the last five years there have been unexpectedly heavy snowfalls and continuously colder temperatures in South Korea (MLTM, 2011a,2011b). Therefore, effective operation of a road weather information system is a higher priority than in the past. In the U.S. for example, ESSs are well established along major freeways to collect road weather observations. This is because road agencies consider general weather forecast information insufficient for maintaining highways, especially during the winter season. In the 1970s, Surface System Inc. developed a RWIS, and then applied this to airport runaways and some freeway ramps. In the beginning of the 1980s, RWISs had been tested in the highway, and appeared to be a success (Boselly, 2001). In addition, specific guidelines were developed to guide the installation of environmental sensor stations based on various factors such as installation cost, road manager 0 s experience, and topographic conditions (FHWA, 2005). In Northern Europe where the winter weather is similar to that of South Korea, such systems were a priority much earlier in North America (Eriksson and Norrman, 2001). The UK 0 s National Weather Service (called Met Office) has provided road weather information service for highway managers for nearly twenty-five years. In Austria, road weather observations are collected through diverse sensors and equipment along the roads at intervals of approximately 10–15 km. In addition, Switzerland and Germany use road weather information extensively for highway management. Recently, in Sweden, a probe car has been used to observe road weather and then transmit observations at real-time to road agencies (Bogren and Gustavsson, 2012). Ideally, ESS would be installed on all road sections vulnerable to snowfall or freezing, but that would be prohibitively expensive. Therefore these systems are implemented and operated at sections Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/tranpol Transport Policy 0967-070X/$ - see front matter & 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.tranpol.2013.12.012 n Corresponding author. Tel.: +82 1020260772. E-mail address: chyang231@gmail.com (C.H. Yang). Transport Policy 32 (2014) 53–59