Amtrak said it will expand its use of a speed restriction system on Philadelphia's northbound rails and abide by other federal directives issued after one of its trains sped into a curve and crashed in the city last week, killing eight people.

The automatic train control system already is being used for southbound trains approaching the curve where Tuesday's derailment occurred. The system notifies an engineer when a train is above the speed limit and automatically applies the brakes if the engineer doesn't slow down the train.

The Federal Railroad Administration on Saturday ordered Amtrak to expand use of the system.

Amtrak said Saturday it would comply, adding that its "overarching goal is to provide safe and secure rail passenger travel."

The company hopes to resume limited service between Philadelphia and New York on Monday and full service on Tuesday.

The Federal Railroad Administration also ordered Amtrak to analyze curves to assess risks on the Northeast Corridor, the busy stretch of tracks between Washington and Boston, and determine if more can be done to improve safety.

"In areas where approach speed is significantly higher than curve speed, the appropriate technology intended to prevent over-speed derailments must be implemented immediately," the agency said.

Amtrak also will have to increase the amount and frequency of signage alerting engineers and conductors of the maximum authorized speed.

Amtrak posted a message on its website Saturday touting a "very strong" safety record, including a claim that yearly derailments fell from 80 to 28 between 2000 and 2014.

"While any train derailment is unacceptable, it has been 28 years since a derailment resulting in a passenger fatality occurred on the Northeast Corridor," the company said.

After the crash, Amtrak President Joseph Boardman vowed to have the next-generation positive train control system in operation along the railroad by the end of the year, as Congress mandated in 2008. The system uses transponders, wireless radio and computers to prevent trains from going over the speed limit.

Company spokesman Craig Schulz said Saturday that Amtrak also plans to look into whether it can partially activate some of the capabilities already installed along the Northeast Corridor without delaying the complete activation of the next-generation system later this year. The system -- which can be programmed with specific speed limits based on work schedules, track curvature and other conditions -- is in service on only 50 of the 226 miles between Washington and New York.

Officials say the railroad has been repairing the tracks, signals and overhead power lines since the crash.

The train was traveling from Washington, D.C., to New York when it flew off the tracks in Philadelphia. About 200 people were injured, and at least eight people remained in critical condition in Philadelphia hospitals Saturday. All were expected to survive.

Investigators have been looking into why the train hit the speed of about 106 mph in a 50 mph zone. The FBI also is looking into the possibility that the windshield of the train was hit by an object shortly before the train derailed. The engineer, who was injured in the crash, told authorities he did not recall anything in the few minutes before it happened.

NTSB member Robert Sumwalt said investigators have been documenting safety features in all cars and testing signals and signal circuitry as the track was being rebuilt.

Sumwalt also said the FBI is investigating the possibility that the windshield of the train was hit by an object shortly before the train derailed. Officials said an assistant conductor said she heard the engineer talking with a regional train engineer and both said their trains had been hit by objects.

A funeral was held Friday on Long Island for Justin Zemser, a 20-year-old midshipman at the U.S. Naval Academy. A memorial service was held Saturday for 39-year-old educational-software executive Rachel Jacobs in New York, and a funeral is scheduled Monday in Holmdel, New Jersey, for Robert Gildersleeve Jr., 45, of Elkridge, Maryland. Gildersleeve was vice president of a food-safety company called Ecolab.