WASHINGTON (Reuters) - The U.S. Federal Railroad Administration has recommended passenger railroads take steps to prevent speeding trains following a deadly Amtrak accident in May in which a train derailed in Philadelphia after entering a curve at double the speed limit.

The agency on Tuesday said railroads should identify locations where trains must reduce speed by more than 20 miles per hour in their approach to a bridge or curve and should modify automatic systems to meet speed limits. It also said railroads should post more signs highlighting the maximum allowed speed.

The agency also said it would enforce a deadline of the end of 2015 for railroads to install new safety equipment known as positive train control. Some passenger and freight carriers are expected to miss the deadline.

(Reporting by Emily Stephenson; Editing by Susan Heavey)