



Amtrak this week threatened to suspend some train service in December unless Congress extends a deadline for adding safety technology.

The rail service faces a Dec. 31 deadline to implement positive train control, a speed safeguard. In a letter seen by Reuters, Amtrak told the Senate Commerce Committee the "vast majority" of its network would become inoperable without an extension, adding that it would start notifying customers of disruptions starting Dec. 1.

Amtrak said it could likely install the safety technology by the deadline on the busy piece of the Northeast Corridor it controls, but will not be able to on a stretch of track in New York and Connecticut. Other railroad lines and the Association of American Railroads have also called for extensions, contending inaction could disrupt rail transport and employment.

Positive train control came under scrutiny in May, when a speeding Amtrak train derailed near Philadelphia on a track that did not have the safety technology. Eight people died in the crash.

Read MoreAmtrak train derails in Vermont, injuring 7

The accident also sparked a national conversation on the state of U.S. infrastructure and Amtrak's ability to pay for upgrades.

— Reuters contributed to this report