More than 11,000 customers rode the train in the four weeks after it entered service Dec. 11. The train's daily roundtrip between Washington and Boston earned more than $1.25 million in ticket sales, beating projections by 12 percent, Amtrak said.

The train was on time - defined as within 15 minutes of its schedule - 94 percent of the time.

Twice during the first week of service, the Acela Express train was taken out of service for unplanned maintenance, and a traditional train took its place for the northbound route to Boston. Both times, the Acela Express train made it to Boston in time to
carry passengers on the daily southbound trip.

The train and its backup are the first of 20 that Amtrak is receiving from Bombardier Transportation of Canada and Alstom Ltd. of France. All 20 are supposed to be running in the Northeast Corridor by next summer.

Amtrak will phase in two more Acela Express round trips in late February.
The revised schedule will include a nonstop, ``super express'' connecting New York and Washington in two hours, 28 minutes.

" We are encouraged by the performance to date and look forward to adding more trains to the service,'' said Amtrak President George D. Warrington.