"Under the current climate of heightened level security, I am concerned about this type of shipment being left unattended, unsecured in a metropolitan area," Battalion Chief Quentin Maver wrote in a memo to his boss.
Some Charlotte-area towns have also grown uneasy about congregations of hazmat cars.
A rail yard in downtown Kannapolis, officials say, is a temporary parking lot for Norfolk Southern trains. Some cars have displayed placards for highly toxic ammonia and corrosive nitric acid.
Apart from safety concerns, city officials say, the cars won't fit in with the multimillion-dollar redevelopment of the former Pillowtex Corp. complex across the street.
"Certainly, it's not something we want to have," said City Manager Mike Legg. "But we've been down there battling with them before. I think they're doing everything they can."
In Huntersville, area resident John Probst noticed chemical tank cars parked along Main Street about a year ago. He looked up the chemical -- toluene diisocyanate, a chemical whose toxic vapors can cause lung damage -- on the Internet and called town hall.
"Those things were literally parked in peoples' front yards over there," Probst said. "If you're going to have a chemical that's that dangerous, it should not be stored outside a locked facility."
Foamex International, whose Cornelius plant uses TDI to make polyurethane foam, says it secures incoming cars behind locked gates. But its chemical supplier is responsible for the cars until they arrive, the company says, and it's up to Norfolk Southern to decide where to park them.
Huntersville had told Norfolk Southern and Foamex that it preferred the cars be parked elsewhere, said Assistant Town Manager Greg Ferguson.
More recently, Probst said, the cars have been parked farther south on a seldom-used track along N.C. 115. That's where five were parked last month.
In response to questions from the Observer, Norfolk Southern spokesman Robin Chapman said tank cars will no longer be kept at that location. They'll instead be moved to its Charlotte rail yard.
Railroad police "can't stand guard 24-7 over a particular train that's parked, but they do patrol periodically," Chapman said. "We rely on all our employees to keep an eye open" for security risks.
Federal rules require hazmat carriers and shippers to develop security plans, including an assessment of risks en route, and instruct employees. But the rules prescribe only "appropriate measures" to be included in the plans, which are not filed with the government.
"It makes a whole lot of people do not very much," said Millar, the consultant, who helped Washington, D.C., try to block hazmat shipments near the Capitol. "Industry does its own self-analysis and does their own security plan, with pretty good odds that nobody is going to look at it."
Last April, the federal homeland security and transportation departments began jointly working to improve security of rail shipments of hazmat that can be toxic if inhaled, such as chlorine.
Among the group's goals, said a spokesman for the Transportation Security Administration, are improving security during rail car storage, enhancing the cars' ability to survive attacks and developing new protective measures.
Stored hazmat is also addressed in a security plan the rail industry developed soon after 9-11, creating four alert levels, says the Association of American Railroads. Spokesman Tom White said he couldn't discuss the details of the plan.
Charlotte industries that receive hazardous materials shipments began beefing up security before the terrorist attacks, said Charlotte Fire Marshal Bart Massey. Most companies wanted to prevent vandalism, Massey said, but "9-11 kicked it into high gear."
The chemical company Rohm and Haas spent nearly $750,000 to upgrade security at its northeast Charlotte plant after 9-11. The plant converts hazardous materials into nonhazardous polymers used in latex paint, adhesives and coatings.
Incoming hazmat rail cars, which once parked outside the plant's perimeter, now sit inside a tall fence. They're also physically inspected for evidence of tampering. Video cameras, lights and an intrusion detection system help keep watch.