Tunnels, Safety and Security Issues in

Types of Tunnel Safety and Security Issues

Tunnel safety and security issues arise in all phases of a tunnel's life, from design and construction through maintenance and operation. Tunnels are by their nature confined spaces with one entryway and one exit. Therefore, incidents or accidents that occur within a tunnel have the potential to result in serious structural damage, injury and loss of life, environmental damage, and/or transportation disruptions. Traffic accidents within tunnels, such as the highly publicized crash that claimed the life of England's Princess Diana in 1997, also present unique challenges.

Tunnel safety and security issues begin to be addressed during the planning, design, and construction phases. The fact that tunnels are constructed underground or beneath bodies of water increases the risks and safety needs inherent in construction.

Tunnel construction necessarily involves disturbances to the rock or soil due to excavation, leading to the potential for ground collapse. Water intrusion can result in flooding, weakening of the soil, electrical equipment malfunctions, and other safety concerns. Other workplace safety issues include noise, lighting and/or visibility, atmospheric conditions, the use of heavy machinery and explosives, and the potential for dangerous fumes, fires, and unplanned explosions.

Fire is one of the most lethal, and therefore most studied, issues involving tunnel safety. More frequent use of tunnels has given rise to more actual and potential tunnel fires, as well as the resulting damage and loss of life.

Tunnels generally have only two entry/exit points, which increases the difficulty of getting firefighters and equipment to the scene and the ability to evacuate people inside. In addition, the confined space of a tunnel also increases the potential for superheated flashovers; concentrates smoke, fumes, flames, and heat radiation; reduces visibility; and hinders escape and rescue.

Hazardous cargo is another significant and growing tunnel safety issue. Incidents involving the transportation of hazardous materials threaten human life, tunnel infrastructure, and the environment, in addition to traffic flow disruption and economic losses.

The transportation of hazardous material cargo has historically received less attention than other tunnel safety issues. Thus, the regulation of hazardous cargoes in tunnels shows considerable variation both within and across local, national, and international levels, but it is a subject that tunnel risk management experts must take into consideration.

The rise of terrorism risks has been heightened in the wake of such highly publicized incidents involving transportation as the September 11, 2001, terrorist attacks in New York City and Washington, D.C.; mass transit bombings in London; and a sarin nerve gas attack in a Tokyo subway. These have raised public awareness of transportation security issues, with bridges and tunnels seen as among the more vulnerable potential targets.

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