Gasoline tanker truck explodes into fire on Seattle's Alaskan Way Viaduct on December 4, 1975.

  • By Daryl C. McClary
  • Posted 1/27/2007
  • Essay 8085
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Early Thursday morning on December 4, 1975, in Seattle, the driver of a tanker truck hauling a full trailer of gasoline loses control of his rig in the southbound lanes of the Alaskan Way Viaduct, in the south end of downtown Seattle adjacent to Pier 48.  The truck jackknifes and the trailer overturns and ruptures, spilling 3,700 gallons of gasoline onto the roadway, which erupts into a wall of flames.  Fortunately, the accident causes no deaths, but six electrical trunk lines are incinerated, leaving several downtown buildings without power including the Seattle Municipal Building and the Public Safety Building, which houses the Seattle Police Department.  Property damage is estimated to be at least $750,000.

Conflagration Possible Becomes Actual

When the Alaskan Way Viaduct (US 99, later SR 99) opened in 1952, there was a total ban against all trucks using the viaduct or the Battery Street Tunnel to transport potentially hazardous cargoes. The Seattle Fire Department said the ban was necessary because flaming liquids flowing down from the viaduct would imperil not only nearby buildings but also trains, cars, and pedestrians underneath the structure.  The ban was eased in 1961 when the Seattle City Council authorized the transportation of heating oil. In 1967, continued pressure from the petroleum and transportation industries caused the City Council to relent further, allowing the transportation of flammable liquids at any time except during weekday morning and evening rush hours.  Fire Department officials warned the City Council “If you ever have a tank-truck fire on either level of the viaduct, you’re going to face a possible conflagration down below” (The Seattle Times).  Before the Fire Department agreed to the changes, the City Council had to finance the installation of water standpipes at intervals of one block along the entire length of the viaduct, to fight fires.

At about 1:00 a.m. on Thursday, December 4, 1975, Richard Leroy Baker, age 40, left the Union Oil of California tank farm (now the Seattle Art Museum’s Olympic Sculpture Park) on Elliott Avenue, north of Broad Street, with a full tank-truck and tank-trailer load of gasoline for delivery to local Union 76 service stations.  Baker was driving southbound in the left-hand lane on the Alaskan Way Viaduct when his truck struck the guardrail at about S. Washington Street (across from Pier 48), and jackknifed.  The abrupt movement caused the trailer, containing 3,700 gallons of gasoline, to disconnect from the tank-truck and overturn. The trailer struck a concrete support column, rupturing the tank and spilling its cargo over the lower deck of the viaduct.  The highly flammable gasoline exploded into a giant wall of fire and flaming liquid cascaded over both sides of the roadway, down 40 feet to the street level, and onto a Burlington Northern Railway (BNR) freight train and several parked cars.

Baker immediately drove the tanker truck, containing an additional 4,800 gallons of gasoline, off the elevated portion of the viaduct to safety.  Firefighters and equipment from Fire Station No. 5, located on the waterfront at the base of Madison Street, were below the scene of the accident within minutes and began pouring streams of water and chemical fire retardant onto the conflagration.  Additional firefighting equipment accessed the burning roadway from the Columbia Street on-ramp and the 1st Avenue S off-ramp.  Approximately 75 firefighters attacked the blaze and brought it  under control within 45 minutes.

Close Calls and Fast Moves

Fortunately there were no lives lost in the accident, but there were some close calls.  Burning gasoline ignited the Alaska Hotel, 75 S Main Street, a three-story brick building located almost directly below the viaduct, housing Shelly’s Leg (Seattle’s first gay discotheque). Some 150 patrons filled the discotheque.  As windows began shattering from the heat, security guards managed to evacuate the occupants through the rear entrance. The flames also damaged several unoccupied buildings in the vicinity.

When the gasoline exploded, two Seattle Police officers were parked in a patrol car underneath the viaduct near Shelly’s Leg, but they were uninjured.  The flaming gasoline also damaged at least 30 automobiles parked underneath the viaduct, 17 of which were total losses.

Burning gasoline also poured onto a BNR freight train, extensively damaging four boxcars.  The railroad crew quickly disconnected the burning cars and moved the rest of the train to safety.  A BNR brakeman, working on the train, was narrowly missed by a set of wheels from the trailer that fell from the viaduct.

Damage to and Below the Viaduct

The heat was so intense that pieces of concrete began falling from the viaduct onto the street.  Six power cables on the underside of the roadway were burned through, blacking out a number of downtown buildings including the Y.M.C.A, the Colman Building, the Seattle Municipal Building, which housed City Hall and the mayor’s office, and the Public Safety Building, which housed the Seattle Police Department and emergency-911 call center.

Fortunately, the blackout did not affect the emergency-911 operators because the system had emergency power generators available.  Unfortunately, Local 77 of the Electrical Workers Union, with some 700 members, was on strike.  When Seattle City Light asked for four emergency crews to repair the power cables, the union’s emergency committee “rejected the manpower request because the power outage did not endanger life” (The Seattle Times).  The power cables were repaired by crews of City Light supervisors and power was restored on Friday, December 5.

Following the accident, both levels of the Alaskan Way Viaduct were closed to traffic until the Seattle City Engineering Department could assess the damage to the structure.  City engineers determined the structure was safe, but ordered crews to chip away loose concrete from beneath the top deck of the viaduct to protect motorists in the southbound lanes from possible falling debris.  The viaduct was opened for morning rush-hour traffic.  Damage to the support beams was repaired later with an epoxy compound.

A Hell of a Problem

Fire Chief Frank Hanson told the news media the accident “had the potential of being as disastrous as any in the city’s history from the standpoint of injuries” (Seattle Post-Intelligencer).  Mayor Wesley C. Uhlman (b. 1935) and the Seattle City Council knew the city had narrowly avoided a catastrophe, but a restoration of the ban on transporting flammable liquids on the viaduct was deemed impracticable.  The City Council had convinced itself that transportation along the waterfront or thorough industrial areas was at least as hazardous as on the elevated viaduct.  Chief Hanson agreed to meet with the National Transportation Safety Board (NTSB) and the National Highway Traffic Safety Administration to discuss means of reducing viaduct hazards, but added: “We’ve obviously got a hell of a problem” (The Seattle Times).

Because of the great potential for disaster, the NTSB took an immediate interest in the accident and dispatched two investigators, Charles P. Hoffman and Hanes G. Gibson, from Washington D.C.  Their report stated that Richard Baker, driving a 1975 Peterbuilt tank truck towing a 1970 Peerless tank trailer, was traveling on a “traffic-polished concrete roadway” at 52 miles-per-hour (posted 45 mph) during a rainstorm when he struck the left-hand guardrail at about S. Washington Street, where the Alaskan Way Viaduct curves 30 degrees to the right, and lost control.  When the combination vehicle jackknifed, the trailer struck a viaduct support column located between S Main and S Jackson Streets, rupturing the tank and spilling its cargo. 

The NTSB determined the accident was caused by driver error rather than an equipment malfunction.  Contributing factors were excessive speed, a wet, slippery roadway and the tank-trailer’s lack of an antilock brake system.  Property damage from the accident was estimated at $750,000.

Sources: National Transportation Safety Board, Report No. HAR-76-07, "Union Oil Company of California Tank Truck and Full Trailer Overturn and Fire Alaskan Way Viaduct, Seattle, Washington, December 4, 1975" (Springfield, VA: National Technical Information Service, 1976); "Fiery Blast Rips Truck on Viaduct," Seattle Post-Intelligencer, December 4, 1975, p. A-1; Martin Works, "Viaduct Fire Sparks Action," Ibid., December 5, 1975, p. A-8; Charles Brown, "Viaduct Fire Leaves Damage in Millions," The Seattle Times, December 4, 1975, p. 1; "Three Buildings Without Power," Ibid., December 4, 1975, p. A-15; "Viaduct Given OK," Ibid., December 5, 1975, p. A-3; "Viaduct's Safety Hazards," Ibid., December 5, 1975, p. A-12.

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