Amtrak President David L. Gunn apologized to Virginia commuters yesterday afternoon for lengthy delays on commuter trains operated by Amtrak that were ordered to crawl at 15 mph Thursday evening because of the weather, while freight trains were allowed to travel at 40 mph.

Virginia Railway Express and Maryland MARC trains were delayed for up to five hours when CSX Transportation and Norfolk Southern Corp. placed the speed limit on all passenger trains because of flash flood warnings.

Freight trains, however, were allowed the higher speed limit on both railroads, and officials said some commuter trains were delayed further when some CSX freight trains were allowed to overtake and pass the slower passenger trains.

Amtrak operates VRE trains under contract. Officials at VRE and MARC joined Gunn in criticizing CSX and said they would ask for explanations from the railroad.

Commuter rail is the fastest-growing form of transit. However, commuter rail operations often must use the tracks of freight railroads, and tensions inevitably arise when the needs of freight and passengers clash.

Adam Hollingsworth, a CSX spokesman, said the speed restrictions were necessary for safety. He said CSX and Norfolk Southern have "the most aggressive safety programs in the railroad industry."

As for allowing faster freight train speeds, Hollingsworth said an engineering study is underway to determine exactly what the speed limit for freight and passengers should be in such conditions. That study was requested by VRE in the aftermath of the February snowstorm, during which CSX shut down all passenger service on its tracks.

No one yesterday criticized Norfolk Southern, which lifted its speed restrictions shortly after 6 p.m. Thursday, allowing VRE trains using its tracks to Manassas to speed up. The maximum delay on the Manassas line was 45 minutes, according to VRE.

CSX did not lift its restrictions till 9 p.m., producing lengthy delays during rush hour. Hollingsworth said the limits were lifted later because it takes more time to perform federally mandated inspections on the longer CSX lines than on the shorter Norfolk Southern line to Manassas.

Hollingsworth said that without a "rigorous factual analysis," it would not be "safe or appropriate" to change speed limits in certain weather conditions.

In a note to passengers left in the seats on VRE trains, Gunn said CSX senior management had assured him after the snowstorm that "speed restrictions on passenger trains would be no more restrictive than those for freights."

"For what it's worth," Gunn wrote, "last night I contacted a senior CSX official and expressed my outrage."

VRE's chief of operations, Pete Sklannik Jr., called CSX's actions unacceptable.

"Last night is another example of putting freight trains ahead of people and their families," Sklannik said in an e-mail note to VRE customers. "Rest assured, we are going to continue to pursue this to ensure that our passengers receive the type of service that will allow them to commute in a safe and timely manner."

The Federal Railroad Administration requires that railroads have an operating plan for flash flood conditions and that track be inspected during such warnings, but it does not set specific speed limits. A Railroad Administration source said officials will talk to CSX and Norfolk Southern about their programs.

The requirement for a flash flood plan grew out of a 1997 wreck of the Los Angeles-Chicago Amtrak train, the Southwest Chief, which derailed at 90 mph near Kingman, Ariz., because of a flash flood. There were injuries but no deaths in that wreck.

Amtrak chief David Gunn said he had been assured that speed restrictions would be equitable.