## 1 Introduction  
Motorways are generally considered safe road infrastructures. That is evident for three main reasons: (1) motorways are thoroughly inspected and monitored, (2) drivers are more precautious when passing through them, and (3) they are unaffected by open road weather conditions. As a result, tunnels are safer than open road infrastructures in terms of accident rates. However, accidents that occur inside tunnels can have a more significant impact and cause more casualties due to the constrained space of the tunnel itself. Moreover, negative consequences can arise when such accidents occur, particularly regarding human losses and damage to tunnel equipment and infrastructure [1]. The most serious threat to road tunnel systems is fire. Destructive events such as the Mont Blanc fire in France (1999) or the fire in Yanhou, China (2014) are only examples of the magnitude of such events. Furthermore, previous tunnel fire accidents have shown that, in addition to the thermal radiation and toxic effects of the trapped fire, smoke inside the tunnel can cause many fatalities among trapped tunnel users, as mentioned by [2]. According to [3], the primary goal of dangerous goods transportation safety management is to reduce the frequency of fire accidents. Furthermore, [4] has emphasized the significance of tunnel operators' information in the event of a fire accident. They have insisted that such details about the specific characteristics of the fire incident have to be delivered to the motorway management staff as soon as possible to take appropriate actions. Furthermore, the substance involved in the accident is one of the most crucial pieces of information to predict fire progression. A significant number of studies focusing on analyzing fire accidents in road tunnels indicate that fire is the most ominous and considerable threat inside tunnels, even though fires in road tunnels are not common cases [5; 6]. Analysis of the Mont Blanc and Tauren tunnel accidents by [7] revealed the implication of hazardous substances, while the primary vehicles were not carrying hazardous substances but were simple HGV (Heavy Good Vehicles). Vehicles loaded with dangerous goods above a certain quantity were not allowed to use the tunnel in the Mont Blanc tunnel. However, as dramatically shown, this ban has not been enough to prevent the occurrence of major accidents, as mentioned by [8]. As mentioned by [9], in a Yanhou 2014 tunnel accident, a coal truck rear-ended a methanol truck (classified as an ADR vehicle--ADR regulation, Section 1.1). It resulted in a massive fire burning for three consecutive days, leading to 40 fatalities and 12 injuries. This event led to the prohibition of ADR vehicle use on the highway for one year. A recent analysis by [10] regarding fire accidents in Chinese highway tunnels has shown that the average prevalence of tunnel fire accidents increased over the last 20 years. Furthermore, as [11] mentions, several aspects of tunnel design and safety regulations need to be reviewed due to their low standards and the severity of modern incidents. Heavy vehicles are also indicated by [10; 12], as the vehicle type is mainly involved in many tunnel fire accidents. The involvement probability of heavily loaded vehicles in fire tunnel accidents is higher in contrast to other types of vehicles compared to their frequency of appearance. Their percentage is even higher when they carry flammable substances [13]. The same has been concluded by [9] study of 156 tunnel fire accidents in China, which recommended that large trucks, especially those carrying hazardous substances, should be tracked and managed during their tunnel passing. Therefore, developing an automated tool to track and efficiently monitor those vehicles' passage is necessary to ensure safer dangerous goods passage from tunnels. As previously stated, this paper emphasizes the significance of an automated tool for identifying and recognizing ADR [14] vehicles before they enter tunnels.