Steve McCan cruised along the Southwest Freeway in his new Grand Prix on a Tuesday morning in 1976, happy to be home from Vietnam and free from the confines of a Navy submarine.

McCan, 27, glanced at a green Volvo and noticed the driver, a young woman with a baby. She's pretty, he thought, as he drove past and into the shadow of the 610 overpass.

Above McCan, in the right lane of Interstate 610, a tractor-trailer struck the bridge rail. McCan watched in his rearview mirror as the truck rolled over the edge and fell about 15 feet onto the freeway. The tractor separated from the trailer, and its tank exploded, spewing 7,509 gallons of anhydrous ammonia. The toxic fog killed six people and injured 178.

Chemical Breakdown In November 2014, four workers died at a DuPont plant in La Porte after being exposed to a toxic gas. Responding emergency workers weren’t sure what was in the air. The surrounding community wasn’t, either. This Houston Chronicle investigation explores how another fatal mistake could have the largest consequences and probes the regulatory failures that put us in jeopardy. Click here to read the series.

Afterward, the National Transportation Safety Board praised the city of Houston for having designated the 610 Loop as the official route for hazardous materials, keeping trucks from more populous areas.

Forty years later, however, the 38-mile route remains the city's designated hazardous transportation route. No longer the outer loop, 610 snakes through a congested city that has doubled in population, leaving Houston vulnerable to a catastrophic accident.

About 400 trucks a day loaded with tons of hazardous chemicals, such as chlorine, butadiene and formaldehyde, inch along 610 in bumper-to-bumper traffic and pass within a mile of NRG Stadium, Memorial Park and the Galleria shopping center.

Nearby cities and towns have even more dangerous routes, designating their main thoroughfares for transporting hazardous chemicals, including Mont Belvieu and Conroe. The last time a route was updated anywhere in the Houston area was more than 20 years ago, according to data from the state Department of Transportation.

Other Texas cities, including Austin, have no designated routes at all.

Designated hazardous materials routes in the Houston area Source: Texas Department of Transportation | Created by Rachael Gleason/Houston Chronicle

Old or nonexistent routes aren't the only safety issue. The U.S. government systematically does not track what's coming and going on the highways and rails, a Houston Chronicle investigation has found. It has the authority to demand manifests but largely relies on companies to operate safely.

Hazardous chemicals roll on tracks past Saturday morning soccer games at the YMCA in Garden Oaks and through congested Highland Village at rush hour. Union Pacific tracks also cross Lake Houston, a major water storage reservoir.

The potential for calamity is real. Since 2000, Texas has lead the nation in fatalities, injuries and evacuations related to moving hazardous chemicals on roads or rails, according to an analysis of incident data from the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration.

The 19 fatal accidents in Texas included a two-train collision in Bexar County involving a tank car carrying chlorine. That accident in 2004 killed three and injured 66.

In February 2014, a state trooper driving near the 610 East ramp and Interstate 45 saw a diesel truck explosion. The trooper found the truck driver lying on the grass by the road. He was on fire.

Last spring, a semi-truck carrying propane collided with another truck. The explosion killed one, injured two and forced 120 people to evacuate.

Fatal hazardous materials incidents in the United States Source: U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration | Created by Rachael Gleason/Houston Chronicle

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State and local officials seem confused about who has the power to designate a hazardous materials route.

State law requires all cities with populations greater than 850,000 to have such routes, and the Texas Department of Transportation is responsible for putting up signs. Austin is the only one of that size without a route. The capital city exceeded that population level in 2012, according to U.S. Census estimates, but is still in the process of choosing a route, according to City Council minutes.

A spokesman for the state Department of Transportation said it is up to municipalities to designate hazardous materials routes. Houston officials insisted, however, that the state also has the power, outlined in Texas Administrative Code, Title 43, Chapter 25, Section 104.

Houston's Office of Emergency Management doesn't know why the city's designated route hasn't been updated in decades. The department said Houston Fire is responsible for oversight of hazardous materials, including transportation.

Spokespersons for the fire department did not reply to requests for comment.

City Council member Larry Green, chair of the Transportation, Technology and Infrastructure Committee, said in response to questions from the Chronicle that he plans to review the 610 Loop's designation and that dangerous cargo should be routed through less-populous parts of Houston.

Steve McCan, who survived the deadly tanker accident in 1976, wishes officials would update Houston's hazmat route and get chemicals off 610. "If something like that was to happen today, how many more people would suffer?" less Steve McCan, who survived the deadly tanker accident in 1976, wishes officials would update Houston's hazmat route and get chemicals off 610. "If something like that was to happen today, how many more people ... more Photo: Michael Ciaglo, Staff Photo: Michael Ciaglo, Staff Image 1 of / 11 Caption Close Hazardous routes to a disaster: Chemicals still roll through populated areas of Houston 1 / 11 Back to Gallery

One government-funded study of hazardous materials required Texas A&M University researchers to stand at rail and road crossings in Houston for more than 300 hours to count signs on cargo because there was no better method available.

The study, done five years ago, found that an average of 468 trucks carrying hazardous materials use Interstate 45 each day, though it is not a designated route. Another 249 per day, on average, use U.S. 59. Trucks are allowed to make deliveries or pickups outside of designated routes.

David Bierling, the study's author, said trucking is essential to the chemical industry in Houston, but he encouraged city officials in 2011 to use the study as a starting point to improve safety.

When the Chronicle asked for the report, city officials said to ask the Greater Houston local emergency planning committee. The committee initially couldn't locate the study, then found it in a storage unit.

Texas A&M hazardous materials study

Federal regulations say that even without a designated hazardous material route, trucks are supposed to avoid heavily populated areas, tunnels, narrow streets or places where crowds assemble.

The rules are not often enforced.

Only specifically trained officers can issue tickets for hazardous materials violations. About 600 Department of Public Safety employees have that training, as do another 175 from local police forces across the state.

From 2013 to June 2015, DPS officers handed out three tickets.

The Federal Motor Carrier Safety Administration also enforces hazardous material transportation rules. It has not issued any fines in Texas since 2010. Nationwide, in the last six years, it handed out 10 fines to trucking companies, for a total of $192,880. Most violations were for not having a written route plan.

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The Union Pacific and Burlington Northern Santa Fe railroads both have large switching yards in Houston and rail lines that run through densely populated neighborhoods, according to the city's emergency management plan.

Railroads carry hazardous materials along with regular cargo, the plan states.

Neither railroad responded to the Chronicle's request to comment on safety precautions.

Tiffany Lindemann, a spokeswoman for the Federal Railroad Administration, said if a train carrying hazardous materials has more than one route option, the railroad must conduct a comprehensive analysis to determine the safest path. Twenty-seven factors, including population and proximity to "iconic targets," should be taken into account as part of assessing risk, according to the FRA. Lindemann said the agency audits the railroads' analyses annually but declined to provide the Chronicle with copies for Union Pacific or Burlington Northern.

Rail carrier regulations also are enforced by the FRA. It issued $24.1 million in penalties for hazardous material violations since 2010. A breakdown for Texas was not available.

The American Association of Railroads made an agreement to provide annual data on hazardous material transportation to any local emergency planning committee that asks for it, but the companies are under no obligation to give that information to anyone else.

When the Chronicle asked the Greater Houston committee for the analysis of hazardous material moved by rail, it was directed to get written permission from the federal secretary of transportation.

Mapping transportation accidents from just one plant Source: U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration | Created by Rachael Gleason/Houston Chronicle

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On that May day in 1976, after the ammonia tank exploded, a piece of metal hit McCan's car, and he pulled over. Two men who drove up beside him fell over onto the payment as fumes poured out of their car.

McCan looked for the woman in the Volvo, but the car had disappeared in a white cloud. He glanced across the highway and saw a businessman step out of a Lincoln town car. They locked eyes for a moment.

The man ran one way; McCan ran the other.

McCan, now a Peterbuilt truck salesman and grandfather of eight, remembers holding his breath that day and trying to outrun the vapor cloud. He remembers jumping into the car of a good Samaritan, who drove him out of danger.

He remembers hearing that afternoon that a car crushed under the ammonia tank held a woman and her baby.

He'd always assumed it was the young mom in the Volvo. But the forensic investigator's reports, stored in the old county archive, show that the woman whose car was crushed was driving an Oldsmobile. The baby in the car, a 5-month-old boy, survived.

He remembers learning that the man that he had locked eyes with had died in a field on the other side of the highway. He had run the wrong way.

Kenneth MacKenzie, Houston's former air pollution control chief, said even in the '70s, the ammonia tanker explosion was a "nightmare" scenario.

He dispatched teams to monitor the air quality and was thankful that the wind had not shifted, or the death toll could have been far worse. Anhydrous ammonia kills by sucking the moisture from vital organs.

"It could have wiped out the Galleria," he said.

MacKenzie, who is now 75, cringes at headlines about chemical accidents.

Some are scarier than others, like the train derailment in 2012 that sent a toxic fog of vinyl chloride over the small town of Paulsboro, N.J. Or the 193-car pileup near Battle Creek, Mich., in 2015 that spilled formic acid and detonated thousands of pounds of fireworks. Or the train derailment this summer along the Washington-Oregon border that spilled tens of thousands of gallons of crude oil and burned for hours.

"You have every kind of chemical in the world coming through Houston," he said. "We've been very fortunate with the amount of problems we've had."

MacKenzie testified at an NTSB hearing on July 22, 1976.

The 610 Loop "was probably reasonable routing at one time, but Houston has grown rapidly," he said then. "Routes for these types of trucks must be put farther away, even if it costs you something extra."

Forty years, three months and 22 days later, nothing has changed.

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Read part 8: Efforts to improve laws eroded by the influence of chemical industry

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Susan Carroll joined the Chronicle in 2006 and works as an investigative/projects reporter. Along with colleagues Matt Dempsey and Mark Collette, her 2016 work on the danger posed by chemical plants in southeast Texas won awards from the National Press Foundation and Investigative Reporters and Editors. Carroll previously covered the U.S.-Mexico border for the Arizona Republic and the Tucson Citizen. She can be reached by e-mail at Susan.Carroll@chron.com or by Twitter: @_SusanCarroll

Matt Dempsey is the data editor for the Houston Chronicle. He joined the Chronicle in 2014 and has worked on several major projects, including the investigation on the dangers of chemical plants. Matt previously worked for the Arizona Republic and Atlanta Journal-Constitution. Contact him at matt.dempsey@chron.com. Follow him on Twitter at @mizzousundevil.



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