[en] A fire occurred in the Caldecott Tunnel on April 7, 1982. This fire was one of five major highway tunnel fires involving large shipments of hazardous materials that have happened worldwide since 1949. In the Caldecott tunnel fire, approximately 32,000 liters (8500 gallons) of gasoline were burned causing about three million dollars in damage to the tunnel (which was reopened approximately 135 hours after the fire), the loss of seven lives, and the destruction of eight vehicles. Shortly after the Caldecott tunnel fire occurred, Sandia National Laboratories obtained permission from the California Highway Patrol to send observers to the fire scene before the debris and other evidence had been removed from the tunnel. The observations made at the scene and the analyses of the information gathered there form the basis of this study. Observation and analyses yield a consistent description of the Caldecott Tunnel fire thermal environment of approximately 1000₀C for 28 to 40 minutes. This environment was nearly uniform for a distance of 100 to 200 meters downwind (east) of the tank truck and trailer. Predictions of the response of a Type B package using simple analytical models indicate that the net thermal energy received by the package is a strong function of the surface and material properties and package design. The thermal input from the tunnel fire may be either greater or less than that from regulatory conditions. The likelihood of a tunnel-fire accident occurring when a Type B package is in the tunnel is small