Locating Road Meteorological Stations Using Analytical Hierarchy Process Method – Case Study, Alborz mountain roads

Roads are part of the development of civilization and support economic activities and the foundation of new life, but unfortunately in the last decade due to low driving culture, non-standard vehicles and roads, environmental factors and increasing traffic volume, number of road accidents increased dramatically. Four human factors, vehicle, road and environmental factors, are always involved in the occurrence of accidents, among which environmental, climatic and climatic factors that occur due to the special geographical conditions of Iran and its mountainous nature, along with other factors play a significant role in accidents. Major road meteorological tasks include continuous preparation of statistics and information, Changes and evolution of meteorological elements in the area of roads covered by the relevant station, Issuance of specific meteorological forecasts along the route in relation to wind intensity and speed, Various storms with lightning and the occurrence of destructive phenomena, Publication of notices and warnings in the event of dangerous weather phenomena on the way, Wind intensity on various stairs and phenomena that are effective in reducing vision, Land and rail transportation is one of the most important issues at the national level. The aim of this study is to locate the meteorological stations of the Alborz mountain axes (Chalous and Haraz) using the Location-Allocation method.

The present study is conducted in the mountainous roads of Alborz (Chalous axis and Haraz axis). Criteria used to locate road meteorological stations include climatic (rainfall of more than 30 mm, avalanche, snow cover, fog, minimum and maximum temperature of -10 and 30 degrees Celsius), geomorphological (rock fall, Landslides and active faults), traffic (accidental points and environmental criteria) and economic-security (traffic). Then, using the Analytical Hierarchy Process (AHP) method, based on the determination of the variable comparison matrix and weighting of each criterion, the final prioritization map is prepared according to the final weight. In the following, based on the Location-Allocation analysis, the proposed meteorological stations on the mountainous axes of Alborz will be determined.

The three meteorological stations of Karaj (from Karaj to km 43), Siah Bisheh (km 43 to 110) and Nowshahr (110 km onwards) reflect the climatic conditions of each section. The number of days recorded for the occurrence of fog at Siah Bisheh station is approximately 844 days in 10-year statistics. Nowshahr and Karaj stations had 70 and 50 foggy days, respectively, in the study of available statistics and information. Therefore, the approximate kilometer of 43 to 110 km in terms of the phenomenon of fog, according to the statistics of Siah Bishe station, has the highest probability of fog days. 60 to 100 km from the beginning of Karaj (middle part of the axis) has a high risk of frost. From the beginning of the axis to 60 km and the approximate area between Vali-Abad and Marzanabad, the risk of frost is moderate. In other parts of the axis, the intensity of frost in the classroom is low and very low. Chalous axis in Mazandaran province from the approximate area of Vali-Abad village to Chalous city includes high and very high risk classes in rainfall of more than 30 mm and Chalous axis in Alborz province experiences low rainfall risk conditions.Due to the minimum threshold temperature in the middle part of Chalous axis, which includes two provinces of Alborz and Mazandaran, it is in moderate danger. This part of the axis includes the range of Nesa, Gachsar, Siah Bisheh and Harijan. Other parts of the axis are in the low risk class. Also, due to the maximum threshold temperature in Chalous axis, the hazardous conditions of the axis in Alborz province are low and in Mazandaran province it is very low.Examining the average of snow cover by the desired months in this study, it can be seen that the middle parts of the Chalus axis experience the highest frequency of snowfall. As we approach the warmer months of the year, a gradual trend of snowmelt is observed. In avalanche risk, the area of Asara village has a moderate risk. The central sections range from Garmab village to Zangoleh bridge in high and very high classes. From the Black Forest area to the end of the Chalous axis, the avalanche falls to the low-lying class.Ranks 74, 78, 82, 84-85, 88-89 have been reported to be affected by the landslide phenomenon. In terms of point density, 78 km to Chalous in Mazandaran province have the highest amount.In sunny weather, km 20-17 and 41, in cloudy weather, km 62, during rainfall, km 40 and 70, in snowy weather, km 40, 60 and 62, and during foggy weather, km 60, 62 and 65 have been the maximum number of accidents.The importance of each of the criteria andsub-criteria was determined according to library studies, installation guidelines for road meteorological stations and expert opinions. The uncertainty coefficient was also 0.6, which is less than the defined 0.1, andaccording to this result, the weighting process is approved. According to global standards and studies conducted, the distance between meteorological stations on the road varies between 30 and 50 square kilometers. In general, each meteorological station can cover an area of about 30 km.Then, using AHP method, the final weight of climatic, geomorphological, traffic and economic-security criteria and sub-criteria in Haraz and Chalous axis were determined. After prioritizing the new stations in terms of need, in the last step, by analyzing LocationAllocation and examining the optimal distances of the axis from the highway, fuel stations, surveillance cameras and villages around the axis, the final stations in priority-oriented are introduced.

Due to the importance of optimal development of the road meteorological network, which reduces road damages and losses and destroys the surrounding environment and economic savings, the optimal location on the Chalous and Haraz axis was examined. The results showed that the required stations on Chalus Road are in the area of Kiasar, Marzan abad, Khargoosh Darreh and Vali abad and Haraz road are in the Polur, Abali, Rahdari and Rineh.