Road Safety Assessment with Emphasis on Environmental Parameters: Dehgolan to Sanandaj Route

A B S T R A C T
The Dehgolan–Sanandaj corridor is one of the key transportation routes connecting Dehgolan County to Sanandaj and serves as a primary access road from Sanandaj to Tehran. Various natural factors influence road-related hazards, including precipitation, slope, elevation, mass movements, freezing, and others. Due to its passage through mountainous areas with steep gradients and diverse environmental and climatic conditions, this route is prone to hazards such as flooding, landslides, and avalanches. This study aims to identify and map the hazard-prone zones along this corridor by considering regional characteristics. To this end, key environmental criteria affecting road safety—including elevation, slope, slope aspect, land use, precipitation, and freezing—were first prepared and standardized. In the next step, the relative importance (weight) of each criterion was determined through expert opinion using pairwise comparisons within the Analytic Hierarchy Process (AHP), analyzed with the Expert Choice software. Finally, a road safety risk assessment map was developed. The zoning results revealed that the vulnerability levels along the studied route are distributed as follows: 56.43% in the very low-risk class, 2.17% in low-risk, 5.41% in moderate-risk, 10.74% in high-risk, and 25.23% in the very high-risk class. Moreover, results indicate that the low-risk zones predominantly occur in areas with 0–10% slope, covering approximately 76% of the route. In contrast, zones with very high risk are mainly located at elevations above 2000 meters, featuring mountain passes and steep slopes, with 21.3% and 3% falling into high and very high elevation classes respectively—collectively accounting for about 1% of the total route area
Extensive Abstract
Introduction
Currently, the functioning and progress of modern society heavily relies on road networks. Road networks are one of the vital networks whose damage can cause excess pressure on other networks, especially in emergency situations. Also, road transport networks, as the most widespread and accessible form of freight and passenger movement, are exposed to a wide range of natural and man-made hazards. Extreme weather conditions or natural disasters can significantly disrupt the transport network. Natural hazards such as floods, landslides, earthquakes and tsunamis have significant impacts on the ability of transport systems to provide safe, efficient and accessible transport. Many road hazards are associated with various climatic, hydrological, geomorphological, etc. factors. In this regard, the geographic information system, with its capabilities of linking spatial and descriptive environmental characteristics, is a suitable tool for assessing road hazards with an environmental approach. any road hazards are associated with various factors, including climatic, hydrological, geomorphological, and other environmental elements. In this context, Geographic Information Systems (GIS), with their capability to integrate spatial and descriptive environmental characteristics, serve as an effective tool for assessing road hazards through an environmentally oriented approach. Accordingly, this study aims to utilize Geographic Information Systems (GIS) and the Analytic Hierarchy Process (AHP) method to identify and evaluate the contributing factors to road hazards along the Dehgolan to Sanandaj route.
 
Methodology
In this study, the Analytic Hierarchy Process (AHP) method based on climatic variables was used to assess road safety on the Dehgolan-Sanandaj axis. In this regard, influential criteria including climatic data, land use, and physiographic characteristics were used to investigate the safety of the Dehgolan-Sanandaj axis. In this regard, six influential factors including slope, slope direction, digital elevation model, land cover, precipitation, and frost were selected. Each of the above criteria was extracted in the ArcGIS 10.8.2 software environment and standardized according to their nature. In the following, the Analytic Hierarchy Process (AHP) method was used to obtain the importance of each of these factors (criteria) in relation to road hazard risk.
 
Results and discussion
The study of the importance of the criteria shows that the slope factor has the greatest effect on the occurrence of road environmental hazards compared to other factors. Also, the land use criterion has the least effect on the occurrence of road hazards. The results show that most of the studied axis is in the low slope and very low risk class, which generally includes agricultural vegetation lands. According to Table (5), about 57 percent of the axis surface has very low risk, about 2 percent of the axis surface has low risk, and about 5 percent of the axis surface has medium risk. Along the Dehgolan to Sanandaj axis, the presence of a high-slope pass in the study area has caused about 10 percent of the axis surface to be in the high risk class and 25 percent of the axis surface to be in the very high risk class.
 
Conclusion
The occurrence of various environmental hazards, including floods, landslides, avalanches, etc., in interprovincial and urban road communications leaves significant human and financial losses. In order to reduce losses and increase the safety factor, it is necessary to predict, examine and analyze hazardous areas using various parameters. In this regard, using climatic, topographic and land cover criteria, environmental hazard zoning was carried out to assess the safety of the Dehgolan-Sanandaj axis. Based on the results obtained from zoning in the studied axis, the risk level of this axis was extracted and identified as 56.43% in the very low risk class, 17.2% in the low risk class, 41.5% in the medium risk class, 74.10% in the high risk class and 23.25% in the very high risk class. The results also show that the low risk class is mostly in the 0 to 10% slope class, which covers 76% of the axis. But the very high risk areas at an altitude above 2000 meters, which have passes and steep slopes, are 21 and 3 percent in the high and very high altitude classes, which cover about 1 percent of the axis area.
 
Funding
There is no funding support.
  
Authors’ Contribution
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
We are grateful to all the scientific consultants of this paper.