Road-traffic-accident (RTA) is a global issue. According to The Organization for Economic Co-operation and Development (2017), around 1.3 million people worldwide die due to traffic accidents each year. Among RTA occurrences, the crashes which occur in the road tunnel always be a flaming issue for the public, and the politician because the crashes occurred in tunnels can trigger the fire and sometimes with an explosion.
This RTA resulting in negative opinion to the people that tunnel is a dangerous infrastructure. Thus, an evaluation about the causes of collisions in road tunnels is compulsory to reduce the risk of accident and give the recommendation for designing safer road tunnels. The main causes of traffic accident are elaborated in the next paragraph. From the road user point of view, there are some behaviors while driving in the road tunnel which can be dangerous. These include conducting land-changing behavior, and speeding when overtaking the front car. Many drivers often perform the lane-changing maneuver to maintain desired velocity and to avoid slow vehicles. This maneuver will exacerbate the situation if they are driving in the road tunnel which has limited space. A common phenomenon when overtaking is accelerated the vehicle speed. Unprepared overtaking can cause head-on crashes because the highest accident probability occurs when the speed accelerates from 65 to 90 km/h, or when the speed is decelerated from 110 to 85 km/h.
The crashes which are occurred due to the vehicle problems generally related to the vehicle brake failure and tire conditions. It is widely believed that excellent brake system can prevent the RTA, some of the main causes of brake failure are the shortage of brake fluid, brake overheating, and undisciplined brake servicing periods. In addition, tire condition is assumed as one of the contributors in the collisions occurrences. Edunyah (2016) found out that over inflation, under inflation, overloading and excessive tire wear are the main causes of tire failure.
While, from the road tunnels perspective, tunnel segment and tunnel length are parameters which can be used to evaluate the cause of RTA. The segment which needs higher consideration is entrance zone. Elaboration of traffic accident occurrences in Norwegian and Singaporean tunnels shows that the entrance zone has the higher rates compared to other segments. In terms of tunnel length, the short tunnels resulted in higher crash rates than long tunnels. The driver alertness is lower in short tunnel compared in a long tunnel because the driver has increased their alertness after passing the transition zone. Based on those points of views, both of road user and the vehicle perspective are mainly laying on the human awareness. The solution for these perspectives is education to raising their alertness. On the other hand, the road condition is always related to the tunnel design, evaluation of road tunnel design is proposed to provide information on how to design safer road tunnels.