Take the transport of dangerous goods. A serious incident involving, say, explosive or toxic chemicals in a tunnel can be extremely costly in terms of loss of human lives, environmental degradation, tunnel damage and transport disruption. On the other hand, a blanket ban on carrying dangerous goods through all tunnels is unthinkable, since it may create unjustified economic costs. Moreover, bans can force operators to use more dangerous routes, such as those through towns and other populated centres.

The rules and regulations for the transport of dangerous goods in tunnels vary considerably among countries and even within countries. This contrasts with the transport of dangerous goods by open road, which are consistently regulated, often based on international model regulations. For tunnels, the definition of regulations, decision-taking, responsibility and enforcement are often left to local or provincial authorities, the tunnel owners, or “expert” opinions. The lack of general rules or regulations that are applicable to all road tunnels at the national level limits the capacity to assess risks and take action.

The OECD and the World Road Association have addressed these problems in this new study, which covers both regulatory and technical issues. For instance, a relatively simple system of grouping dangerous loads has been devised, which transporters could refer to when planning their route. Currently, transport operators have to refer to extensive lists of goods and quantities which are banned from individual tunnels. A quantitative risk assessment model has been developed to compare the risks involved in transporting dangerous goods through a tunnel, with the risks taken on alternative routes. In addition, extensive work was done to study the effectiveness of risk-reducing measures such as drainage, ventilation or fire detection systems.

One encouraging message is that, with the right management, tunnels have a good future. Improving incident prevention and construction techniques means they are increasingly safe and cost-effective for crossing difficult terrain, and also for traversing urban areas, reducing local environmental impact from roads and traffic. Road traffic using these tunnels (heavy goods in particular) is increasing, though, which makes the arrival of this new study all the more welcome.

©OECD Observer No 229, November 2001