Illegal carriage of dangerous goods and their effects on tunnel safety

Consequent to a recent fire resulting from a truck carrying illegal diesel outside a tunnel in Hong Kong, people are quite concerned about the safety aspects of vehicular tunnels. That truck was an ordinary vehicle without appropriate protection against the possible accidental fires due to those liquid fuels. The safety impact on a vehicular tunnel of a fire in an unprotected truck carrying illegal diesel is studied in this paper. Empirical results on spill fires and cooling jet expressions were applied to assess the probable tunnel environment. The two-layer zone model CFAST was also used to verify the results. The smoke temperature in the tunnel within 100 m of the fire might be up to 300°C, and smoke would travel rapidly. It is recommended that a proper safety management scheme should be worked out by the tunnel management authority. If necessary, every truck of enclosed structure should be inspected before entering a vehicular tunnel longer than a specified length, say 230 m.