Hell on rails: the Industrial Accident Scenario: fires spread from a tanker car and jeopardize the facilities of Texas' largest city. "Houston, we have a problem," is the understatement of the day

Risk & Insurance, April 15, 2004 by David Miller

The Hypothetical Scenario:

The fire begins in a rail tanker car loaded with gasoline in the railyards within the international port serving the petrochemical refineries along the shipping channel in Houston.

The yards are unusually crowded with a three-month backlog of tanker cars and other rolling stock following a labor dispute and above-average summer demand.

Fanned by strong onshore winds, the fire spreads from tanker to tanker, incinerating the power lines so that the emergency water systems fail and emergency responders are unable to contain the blaze. The railcar tankers are temporarily parked along sidings adjacent to a tank farm, and despite the best efforts of the firefighters, flames reach to first one and then several 10-million gallon oil-storage tanks.

The flames from these tanks reach 100 feet into the sky, and as the sides of one of the tanks ruptures, a river of burning oil gushes across into the neighboring liquefied natural gas facility, the site of a series of giant pressurized tanks.

The fierce heat causes the first tank to explode. The blast, equivalent to 100 tons of TNT, destroys buildings and equipment within a radius of half a mile. Windows break in buildings up to three miles away. Two other tanks explode before the fire is over.

However, alongside the gasoline tankers are two rail tankers containing 90 tons of liquid chlorine, destined for the water treatment plants of Houston.

The fire ruptures the first of these tankers, releasing a poisonous cloud of gas, lolling three emergency workers and forcing firefighters back half a mile.

Fire captains order breathing equipment to be worn and order the evacuation of everyone within two miles of the rail yard. Choking chlorine gas billows out from the fire and envelops several streets and a hospice before the evacuation can get underway.

An estimated 180 people are killed in their homes, while several hundred are rescued and sent to the hospital with breathing difficulties and burning throats.

Concentrations of chlorine gas--as dense as 500 parts per million--form a lethal cloud that extends over an area of more than two square miles. Concentrations sufficient to cause breathing difficulties extend for several miles downwind. Police begin to evacuate populations in Galena Park and Jacinto City, close to the toxic cloud.

The next day, four million residents of Houston awake from the force and the noise of the explosions as dawn breaks over the threatened city. The smoke from the fire is visible as a pall rising in the distance.

Emergency services from five counties are attending the fire, and the sounds of their sirens, trucks and aircraft can be heard for several blocks. TV news channels provide uninterrupted coverage, and broadcast the pleas from Houston authorities for people to stay home.

Roads leading out of the city to the southwest become choked with ears as people try to leave. Emergency vehicles continue to move toward the fires as the acrid stench of yellowish chlorine descends over the stricken metropolis.

Many people are coughing. Some exhibit mild-to-serious breathing difficulties as they evacuate the area. Medical teams treat thousands of people with respiratory problems.

As the morning winds pick up, rescue teams become increasingly concerned about the possibility of the smoke and chlorine gas being blown across the city.

Air quality monitoring shows that chlorine levels are rising over a large area. Nearly a million people are already on the move. Roads are choked with traffic. The exodus proceeds slowly.

Air conditioning systems in cars provide no protection against the chlorine fumes. Officials move through the traffic jams encouraging people to pull their cars over and walk. By mid-afternoon, hundreds of thousands of people are walking out of the city to rally points where buses and volunteer drivers ferry people to shelters outside the city. Most of the chlorine gas is evaporating in the afternoon heat or dissipating in the breeze.

By evening, the fire is still burning but the levels of chlorine contamination, monitored within the urban areas, are falling as the chlorine becomes diluted in the breeze.

The fire at the port continues to burn throughout the night as firefighters bring the flames under control. It will continue to smolder for several days. City authorities finally declare an end to the emergency after three days. People begin to return to their homes but many complain of lingering chlorine smells and leave again to stay outside the city.

In the fire, explosion and toxic fumes, 600 people die--the most lethal industrial accident in United States in 100 years. Nearly 7,000 people are hospitalized, most of them suffering from chlorine gas or smoke inhalation. Paramedics and medical volunteers during the evacuation treat another 250,000 people. Because the fire occurs in the early hours of the morning, few injuries are caused to people at work keeping workers' comp claims relatively light.

Major parts of Houston's port and nearby refinery have been destroyed. Two ships in the channel are badly damaged and parts of the port remain closed for more than a month.