Freight railroads say service could be halted unless safety technology deadline is extended

Freight railroads are warning they may halt certain toxic chemicals shipments and stop allowing passenger trains to use their tracks if Congress doesn't extend a looming deadline to start using certain safety technology.

The railroads say in letters to the Senate Commerce Committee that they won't have the technology in operation by Dec. 31, the deadline set by a 2008 rail safety law.

The technology, called positive train control, automatically stops trains to prevent collisions with other trains or derailments due to high speeds.

Sarah Feinberg is head of the Federal Railroad Administration. Feinberg has said her agency intends to enforce the 2008 law, including possibly applying fines.

The technology is required on tracks used by passenger trains and to transport chemicals that are toxic to inhale.