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Numerical Simulation of the Caldecott Tunnel Fire, April 1982.


pdf icon Numerical Simulation of the Caldecott Tunnel Fire, April 1982. (444 K)
McGrattan, K. B.

NISTIR 7231; 21 p.

, December 2005.

Keywords:

tunnel fires; tank trucks; simulation; geometry; thermal environment; gasoline; spill fires; fire models; experiments; highways; gas temperature; surface temperature; wall temperature

Abstract:

In the early morning of April 7, 1982, a gasoline tanker truck travelling westbound in the No. 3 bore of the Caldecott Tunnel overturned and caught fire as a result of a multi-vehicle accident. The tunnel connects Oakland andWalnut Creek, California. The National Transportation Safety Board (NTSB) and the California Highway Patrol (CHP) conducted investigations of the accident. In addition to a detailed account of the events leading up to the fire, their reports contain information about the tunnel, the damage to the vehicles, walls and fixtures, and various other details. As part of its on-going study of the safety of waste transportation casks, the US Nuclear Regulatory Commission (NRC) requested that the Building and Fire Research Laboratory of the National Institute of Standards and Technology (NIST) perform numerical simulations of the fire to assess the thermal environment within the tunnel. The results of the simulations were used as boundary conditions for a detailed thermo-structural analysis of a transportation cask. The simulations described in this report were not intended to replicate every detail of the fire, since the information about the gasoline spill, tunnel lining materials, etc., was not known to a high enough level of certainty to permit an exact reconstruction of the event. The approach taken was to use what information was known about the incident as a starting point for the calculations, and then to vary the unknown parameters to ascertain the range of possible outcomes. A similar study to that presented here was conducted by NIST to estimate the thermal environment of the Howard Street Tunnel in Baltimore, Maryland, following the derailment in July 2001 of a freight train and the burning of spilled tripropylene and the contents of surrounding rail cars. The similarities and differences between the Caldecott and Howard Street Tunnel fires are discussed in this report.