Instructor at Üsküdar University Department of Occupational Health and Safety, Road and Traffic Safety Consultant Özgür Şener, discussed why tunnel accidents are more critical.
Accidents in Tunnels Can Be Much More Complex
Özgür Şener stated that traffic accidents on highways can always have serious consequences, adding, “However, accidents in tunnels can be much more complex than those on open roads. An accident that may occur especially in long underwater tunnels can lead to many additional negative consequences such as fire, smoke, loss of visibility, unsafe behaviors of exposed people due to panic, evacuation difficulties, and secondary collisions.”
A Small Incident in Tunnels Can Quickly Escalate
Özgür Şener reminded that drivers have alternative routes and escape areas on open roads, stating, “While open roads offer escape areas, alternative routes, and natural ventilation options for drivers, tunnels are enclosed and limited spaces. Therefore, even a minor incident can quickly turn into a serious safety problem.”
Özgür Şener explained some distinctive features of accidents occurring in tunnels as: “Limited escape areas, especially the inability to evacuate the area before the accident zone in one-way tunnels, panic-driven behaviors of drivers and passengers causing new dangerous situations, rapid spread of flames and smoke in case of fire leading to life-threatening danger, more difficult access for emergency response teams due to restricted movement space, easier occurrence of chain collisions due to insufficient attention to following distance, sudden decrease in visibility if there is smoke in the environment, and very rapid temperature rise in case of fire causing life-threatening danger.”
Şener stated that for this reason, tunnels worldwide are designed and operated with higher safety standards than normal highway sections.
Underwater Tunnels Have a Multi-Layer Security System
Özgür Şener stated that high-resolution camera systems, artificial intelligence-supported incident detection technologies, fire detection systems, emergency escape corridors, and advanced communication infrastructures are used in modern underwater tunnels, and continued as follows:
“Modern underwater tunnels are equipped with multi-layer security systems. The entire tunnel is monitored with high-resolution cameras. Operators track traffic flow in real-time and can initiate immediate intervention in any unusual situation. Thanks to artificial intelligence and image processing technologies; unusual situations such as stationary vehicles, vehicles going in the wrong direction, traffic slowing down compared to routine flow, lane violations, smoke formation, objects falling onto the road or spills of liquids such as oil, etc., can be detected within seconds. Tunnels are equipped with temperature sensors, smoke detectors, and fire detection systems. In a potential fire situation, ventilation systems automatically activate to control the smoke evacuation direction. In long tunnels, emergency exit doors and escape galleries are located at regular intervals. These areas allow people to reach safe zones. Drivers can be informed instantly through emergency telephones, announcement systems, and radio broadcast integrations. Especially in underwater tunnels, pressure, deformation, water leakage, and structural movements are continuously monitored with sensors. Potential risks are attempted to be detected before they reach a more critical level.”
Regular Maintenance and Inspection are of Great Importance
Özgür Şener noted that the mere presence of security systems is not enough, and regular maintenance and inspection are of great importance, stating, “In international practices; periodic safety drills involving different scenarios are conducted. Fire scenarios are tested. Camera and sensor systems are regularly checked. Ventilation performance is continuously measured. Emergency evacuation times are evaluated. Independent technical audits are performed. The aim is to ensure that systems work not only in theory but also in practice during any emergency.”
A Significant Portion of Tunnel Accidents are Human-Caused
Özgür Şener stated that research shows the human factor is effective in most tunnel accidents, saying, “Drivers may unknowingly increase their speed in tunnels due to changes in distance perception. Due to the enclosed environment, drivers may follow the vehicle in front more closely than usual. This can lead to chain collisions during sudden braking. As driving takes place on a closed and confined route, phone use, preoccupation with navigation, or in-car distractions negatively affect safe driving in the tunnel. Although lane changes are not desired in tunnels, unexpected lane changes and sudden maneuvers, especially by impatient drivers, can cause accidents.”
Şener explained that engine failures, tire blowouts, running out of fuel or electricity, and load-related problems are also among the important causes of unplanned stops in tunnels and the negative events resulting from these stops.
Driver Psychology Can Affect Safety
Şener stated that stress levels can increase in individuals with a tendency for claustrophobia, and said, “While believing in the importance of revealing this through interviews with those involved after incidents, the negative effect of increased stress on driving in individuals with claustrophobia, reduced attention due to monotony in long tunnels, inadequate or inappropriate lighting and roadside reference lights not providing enough information to the driver, uncontrolled speed caused by the tension of the enclosed space and the desire to reach the exit as soon as possible, and reduced environmental awareness due to focusing on the exit point can negatively affect driver performance.”
Özgür Şener also stated that the effect of transitioning to a different light level from daylight when entering the tunnel, and similarly, the adaptation of the eyes to changing light levels when exiting the tunnel, can cause short-term vision problems and lead to unsafe driver behaviors.
Speed Limits and Following Distance Must Be Obeyed
Şener stated that obeying speed limits and maintaining a safe following distance are of great importance for safe driving in tunnels, and offered the following advice to drivers:
“If there is an announcement system inside the tunnel, these announcements and driver warnings must be listened to carefully and obeyed. Speed limits set by the tunnel authority must be strictly followed. The safe following distance determined by the tunnel authority must be maintained, and if necessary, the following distance should be increased by carefully observing the behavior of drivers ahead. Headlights should be kept on for visibility. Lane changes should not be made. Mobile phones and other distracting devices should not be used. Sudden braking should not occur at the tunnel entrance. The vehicle's fuel and energy status should be checked before entering the tunnel.”
Do Not Panic in an Emergency
Şener stated that in the event of a possible accident or fire, drivers should primarily follow the announcements of the tunnel management, adding, “It is essential to try to act safely and in a controlled manner by making a correct situation assessment, not with assumptions and panic. The most important issue is to fully comply with the announcements of the tunnel authority and the instructions of the tunnel emergency teams. Because the authorities know and evaluate the entire negative situation. Especially in the event of a fire, the first few minutes are critically important. People's priority should not be to save their vehicles or valuable equipment if they have any in their vehicles, but to reach a safe area in the safest and shortest possible time.”
Safety is a Shared Responsibility
Özgür Şener, stating that tunnels are among the safest transportation structures in the world from an engineering perspective, concluded his words as follows:
“Tunnels are indispensable elements of modern transportation and are among the safest transportation structures in the world from an engineering perspective. However, the sustainability of this safety depends not only on advanced technological systems but also on drivers' compliance with the rules. Obeying speed limits, maintaining following distance, and knowing emergency procedures significantly reduce the risks that can be experienced in tunnels. Especially in underwater tunnels, safety is not only an engineering matter but also a shared responsibility shaped by driver behavior.”
