Fire Protection of Bridge Cables

Abstract

Large suspension bridges are increasingly being exposed to greater fire risks as the volume of traffic carried by them increases. A serious truck fire in 2013 on the New Little Belt Bridge in Denmark threatened the integrity of the bridge due to fire exposure of the main cable at its lowest point. Compared to fuel tankers, the relatively high number of trucks carrying normal but flammable goods makes serious truck fires more likely. Such fires can lead to strength reduction or cable failure that could result in a reduction in bridge load rating and the need for long-lasting repairs. A concept and design for passive fire protection for main cables of large suspension bridges have been developed, tested and implemented. Two major Danish suspension bridges have been retrofitted with this design. The type and extent of fire protection are established through risk analyses, fire testing and investigations involving the cable steel, the fire protection material and the installation method. The extent of emergency preparedness and the timeline for fire-fighting actions are also taken into account. This paper describes a systematic approach to design, evaluate and provide fire protection systems for suspension bridge main cables.