Every day, railcars filled with dangerous chemicals that could take out much of Center City move unhindered and unnoticed from one end of Philadelphia to the other.
It's one of the most daunting risks to the city's security - and one City Council may try to stop.
Frustrated by the lack of federal action to secure the nation's rail lines, more cities are trying to take matters into their own hands, considering laws to block the transport of hazardous rail cargo through neighborhoods.
The District of Columbia was the first to attempt to force detours, with Chicago, Cleveland, Baltimore, Las Vegas and now Philadelphia thinking of similar steps. This year, Washington's city council banned rail shipments of hazardous materials through the district. Tankers with poisonous chlorine gas used to pass four blocks from the Capitol.
But the Washington ban is on hold as CSX Corp. - joined by the Bush administration - challenges the legality of the local law in federal court.
Railroads argue that cities have no business interfering with interstate commerce. Regulating interstate commerce is the job of the federal government, and the Justice Department concurs.
The rail industry, too, warns that such hazmat detours would cause chaos in commerce.
"This is a situation that creates confusion and could ultimately bring the rail system to a halt," said Robert Sullivan, a CSX spokesman.
He said industrial customers, like refineries and bulk shippers using the Philadelphia port, need to be able to move materials through the region. In testimony last month before City Council, Sullivan said half the local traffic CSX handles is for chemical customers.
But the fear among local lawmakers and environmental activists is that terrorists could turn railcars carrying dangerous cargo into weapons.
"I'm not a Luddite who wants to go back to the preindustrial age, but there are more opportunities than are being taken to reduce hazards," said Stuart Greenberg, an emergency management committee member in Cuyahoga County, Ohio, which includes Cleveland.
A bill introduced in October in City Council would allow shipments of hazardous materials to customers inside the city - but would prohibit dangerous cargo from passing through on its way to New Jersey or Baltimore.
"If there is an opportunity to reroute some of these hazardous materials, we need to seriously look at that," said Councilman Darrell Clarke, who introduced the bill.
For Russell Meddin, the fear comes down to this: He doesn't like the idea of chlorine tank cars idling next to his Logan Square neighborhood.
And that's just what happens, he says.
Meddin said CSX, which took over the former Conrail rail operations in Philadelphia, often uses the rail line next to Schuylkill River Park to temporarily park trains, often ones hauling hazmat tank cars.
"As someone who uses the park, I'm gravely concerned that hazardous material is brought into residential areas of the city of Philadelphia," Meddin said.
Meddin works for a neighborhood coalition that is battling CSX on another issue: access to the city's new riverside park. CSX is trying to stop pedestrians from crossing its tracks at Locust Street to enter the park.
The neighborhood group - the Free Schuylkill River Park Coalition - alleges that CSX frequently uses a second rail line next to the river as a parking lot for trains when its railyard is busy.
On its Web site ( www.freetheriverpark.org), the group has photographs of parked hazmat tankers, as well as a video clip of a chlorine gas car slowly passing the park on the western edge of Center City.
"Not even an accident, but just a malfunction of a tank car could kill hundreds or thousands of people," Meddin said. Earlier this year, a rail accident involving a chlorine tanker killed nine people and injured about 250 in Graniteville, S.C.
"If this happened anywhere in Center City, it would shut down the city for weeks," Meddin said.
Al Caporali, a community activist from Southwest Philadelphia, is also alarmed by hazmat tankers routinely parked for upwards of an hour near his home.