Caldecott Tunnel fire

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The Caldecott Tunnel fire killed seven people in the north tube of the Caldecott Tunnel, on State Route 24 between Oakland and Orinda just after midnight on 7 April 1982. It is one of the few major tunnel fires involving a cargo normally considered to be highly flammable, namely gasoline; most tunnel fires have involved less volatile materials.[citation needed]

The Caldecott tunnel complex consists of three tunnels side-by-side, each just over a kilometer long. The north tube, where the fire occurred, is dedicated to westbound traffic. It has a slope of approximately 4.7%, going downhill from the entry portal to the exit portal.

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[edit] Description of events

Shortly after midnight a driver drifted out of lane and her car struck the tunnel wall. She was legally drunk at the time. She brought the car to rest in the left-hand (fast) lane and got out to inspect the damage. The car was almost half-way through the tunnel. The initial accident created a bottleneck for traffic coming up behind. However, due to the late hour of the accident, there were few other vehicles on the road.

A few minutes later, a double tanker (fixed tank plus trailer-tanker) carrying gasoline arrived at the bottleneck. By chance, there was an empty bus close behind it.

The tanker hit the car. The tanker driver then braked to a halt almost exactly half-way through the tunnel. The bus hit either the car, the tanker or both: the bus driver was thrown clear of his vehicle, which continued driverless along the tunnel and crashed into a bridge column not far outside the exit portal.

The driver of the tanker investigated the state of his rig; it was clearly unable to move, the trailer tanker was leaking gasoline into the gutters and small fires had started around the leaks. He ran downhill and made it safely out of the exit portal of the tunnel. By this time, burning gasoline from the punctured tanker was flowing down the drainage system.

The natural draught in the tunnel (and the 4.7% gradient) acted as a chimney encouraging the smoke to flow uphill towards the oncoming vehicles and out of the entrance portal. The tunnel ventilation system, which was not switched on at the time of the accident, remained off throughout the event except for a brief period when the level of carbon monoxide exceeded the trigger level.

Approximately 20 vehicles entered the tunnel in the next few minutes. Most drivers managed to reverse out, prompted by the smoke moving towards them. Four vehicles were trapped behind the burning tanker: a private car, a beer truck and two pickups.

The two occupants of the vehicle closest to the fire (one of the pickups) began to reverse out but soon left their vehicle and walked back uphill to warn the road users behind them. Approximately five minutes after the initial crash, one of the pedestrians called for help at one of the emergency telephones. Shortly afterwards, the fire suddenly increased in size and she was overcome by smoke: the tape recording of the call is blank.

Farther east, the occupant of the other pickup left his vehicle and ran out of the entrance portal. The two (elderly) occupants of the private car were overcome by smoke without ever leaving their vehicle. The two occupants of the truck were also overcome by smoke, and collapsed and died as they stepped out of the truck cab.

In all, two people died in the initial crash, five were killed by the smoke and fire and two were hospitalized for smoke inhalation. All others escaped unharmed.

Unknown to the people fleeing east in the tunnel there were safe passages between the two bores at intervals; these might have enabled some to escape from the fire and smoke, but none of the unlocked doors available were used.

[edit] Casualties

Killed

  • Janice Ferris (driver of the stalled car)
  • John Dykes (driver of the bus)
  • June Rutledge (on emergency telephone when a fireball occurred)
  • Everett Kidney (in the beer truck)
  • Edward Young (in the beer truck)
  • Katherine Lenz and George Lenz (stayed in their car)

Injured

  • Steve Rutledge (in the pickup closest to the fire)
  • Paul Petroelje (in the other pickup)

[edit] Emergency Response and Fire Development

The Caldecott tunnel complex has a permanently manned control room, and the vibrations from the initial accident were felt by those within it. The operator could also see the bus on CCTV when it emerged from the tunnel and crashed into the column.

Crews were dispatched from two local fire brigades, Orinda and Oakland. Emergency services at the entry portal took charge of those evacuated from the tunnel, while the emergency services at the exit portal were able to walk uphill to within a few tens of metres of the fire.

The first concern of the brigade was to ensure that the gasoline running down the drainage system did not pose an explosion hazard to their firefighting efforts. Unfortunately the valves that should have been used to divert the drainage outfall to a hazardous materials sump were rusted stuck and the gasoline went into a nearby lake.

Firefighting at the site in the tunnel began at 1:30 a.m. once the potentially explosive atmosphere at the lake was under control. However, the heat of the fire had seriously affected the integrity of the tunnel firemain, and the water pressure was insufficient to support a hose stream. In the absence of an effective means of fighting it, the fire was allowed to burn out and the remnants were extinguished with foam and dry powder. The Stop message was issued at 2:54 a.m.

[edit] Extent of Damage

The fire burned for between twenty-eight and forty minutes and in this time most of the 8,700 gallons (33,000 litres) of gasoline carried by the truck were consumed. About 250 gallons (1,000 litres) were either discharged into the drainage or recovered from the tanker.

All the heat and smoke from the fire went uphill towards the entry portal, 1720 feet (525 m) away. There was no fire damage west of the fire site.

Brass vehicle components at the tanker melted, indicating that temperatures were slightly over 1800 °F (1000 °C). However, no examples of melted copper (melting point 1981 °F/1083 °C) were found during the clear-up operations, which indicates that the temperatures did not exceed 1800 °F (1000 °C) by much.

The tiles and grout on the walls of the tunnel were damaged and spalled all the way to the entrance portal, 1720 feet (525 m) away.

Over the first 750 feet (230 m) east of the fire site there was spalling of the concrete false ceiling and of the concrete walls behind the tiles. Spalling stopped at the steel reinforcement, approximately 3" (75 mm) below the concrete surface.

Over the first 675 feet (205 m), the steel blanking plates over the ventilation flues in the false ceiling (these blanking plates are used to balance the air supply and extract rates) were buckled by heat and had to be replaced.

The tunnel's wall tiles, firemain, lighting, communications, signage and emergency panels had to be replaced over the whole of the east portion of the tunnel. The ceiling tiles had previously been removed due to poor adhesion. As part of the reconstruction project, enameled metal panels were used to cover the ceiling concrete. The costs of the reconstruction project totaled more than $3 million.

[edit] Sources

[edit] Further reading

  • National Transportation Safety Board, Highway Accident Report - Multiple Vehicle Collision and Fire, Caldecott Tunnel near Oakland, California, APRIL 7, 1982 NTSB/HAR-83/01, 1983.
  • Jackson, L., Serious Tunnel Fires with Emphasis on the Caldecott Tunnel Fire, Oakland, California April 7, 1982. Transportation Research Board Committee A2C04, Tunnels and Underground Structures, 1983.