It's happened again. AP reports that a CSX train carrying crude oil from North Dakota derailed yesterday on a bridge over a river in Philadelphia.

Local police contacted the Coast Guard at about 1 a.m. Thursday to report that a train had derailed on the Schuylkill Arsenal Bridge.

The Coast Guard says in a news release that a small crew on a boat is monitoring the derailment near the bridge and another team that monitors for pollution is also at the scene. Authorities say there’s no report any of the oil has leaked from the cars. It’s not yet clear what may have caused the train to derail. reports that the derailment location is in a densely populated Philadelphia neighborhood adjacent to Drexel University, Childrens Hospital and the entire University of Pennsylvania complex. The incident made history as the 6th derailment of Bakken Shale oil trains in six months. The derailment was a near-disaster. Its the only known derailment of a Bakken Shale oil train which did not result in a major fire, series of explosions, toxic smoke plumes or evacuations.

Parts of the Schuylkill Expressway were reported to remain closed for 12 hours, as the danger of the derailed train exploding, burning, and spilling flaming oil below remained a live risk. As this story goes to press, several train cars, including at least one carrying crude oil, remain twisted off the tracks, just hanging on where the century-old railroad appears broken.

In all, seven cars of a 101-car CSX train from Chicago derailed on the Schuylkill Arsenal Railroad bridge over the Schuylkill River. Six were carrying crude oil, and one was carrying sand. The bridge runs just south of the South Street Bridge from University City to Grays Ferry. It also runs over the heavily travelled Schuylkill Expressway, which was shut for hours following the derailment.

At least twice each day, one-mile-long Bakken Shale oil trains per day pass right over and along the Schuylkill River, on old elevated tracks near Drexel University and 30th Street Station, past Woodlands Cemetery and Bartram Gardens, and onward deep into South Philadelphia to terminate at the newly re-named “Philadelphia Energy Solutions” refinery.

Because of the huge explosions the trains are causing, residents near areas where the trains have blown up are calling the trains “oil bombs.” The recent explosion on December 30th, 2013 in Casselton , North Dakota, created a mushroom-shaped fireball that left eyewitnesses stunned. All residents within a five-mile radius were urged to evacuate to avoid breathing the toxic smoke, which rolled in heavy plumes.

Most Philadelphians live within five miles of the Bakken Shale oil train tracks. There is no evacuation plan for an incident on this scale, despite the fact that Bakken Shale oil trains have blown up five times in six months. The most recent incident, in New Brunswick, Canada on January 7th, involved 17 cars derailed. Oil and gas tank cars burned all night and into the next day, with 150 people evacuated in the relatively remote area.

A railroad CEO and lifelong “railroad man,” E. Hunter Harrison, said on January 15th, 2014 that the tank cars used to ship the Bakken Shale oil not only are unsafe, but should be stopped immediately.

“The 111 tank cars that you hear so much about, if I was calling the shots would be stopped tomorrow,” Harrison said, speaking with Tyler Matheson on CNBCs Nightly Business Report. “They're not ready, they're not equipped for that commodity [Bakken Shale crude] as I see it, they've been controversial for two decades now, so that needs to change.”

Harrison began his half-century career in 1963 as a carman-oiler on the Frisco, and then moved on to the Burlington Northern in 1980 and the Illinois Central in 1989. Harrison took the reins as CEO of Canadian Pacific in June 2012, and in 2013 Morningstar named him CEO of the year.