Improving the Functionality and Resilience of Roadway Tunnels

Road tunnels are an important component of transportation infrastructure. Increased urbanization, population density and traffic congestion demand greater investments in underground transportation infrastructure. Underground transportation offers better traffic efficiency and long-term sustainability, but it also poses special design, operation and maintenance challenges. Public safety and traffic efficiency can be severely affected when hazardous events cause a major tunnel in a high capacity road network to partly or fully lose its functionality and resilience.

There are many issues and operational parameters unique to tunnels that are not encountered in open traffic networks. For instance, fire in tunnels behaves differently from typical fires in open space due to limited intake of oxygen, large amounts of smoke, potential toxic gases and a high level of heat. Moreover, the impacts of hazardous events are more severe in tunnels than in roads, highways and bridges. Collateral damage to a tunnel’s structure and equipment can lead to lengthy tunnel closures. Alternate routes used during closures tend to be narrower roads with lower speed limits, causing traffic delays and congestion. More importantly, existing methods to analyze, predict and mitigate the occurrence and impact of hazardous events for road traffic cannot be applied to tunnels.