Beginning January of next year, the Massachusetts Bay Transportation Authority (MBTA) will extend the weekend hours of its bus service and subway and trolley lines, pushing Boston's unofficial city curfew back two hours.

The extension of hours, ordered Thursday by the Massachusetts Legislature's joint House and Senate transportation committee, will be instituted on a trial basis for nine months while the legislature decides whether to implement it permanently.

Under the pilot program, the MBTA's trains and some bus routes will remain open for riders until about 2:30 a.m. on Friday and Saturday nights. Currently, the last subway cars leave downtown at about 12:30 a.m.

On Thursday, the committee held a required public hearing about the bill, which aims for an independent study of the feasibility and fiscal risks of T trains running longer hours, according to bill sponsor Senator Steven A. Tolman (D-Brighton).

January 2000 is the earliest possible start date for the program, according to MBTA chief operating officer Michael H. Mulhern.

For the next 30 to 45 days, the MBTA will draw up a plan for implementing this trial measure and then send it to the legislature for study.

Senate chair of the joint committee Robert A. Havern '72 said once the report is issued the House and Senate will rubber-stamp the measure.

Proponents of the bill said the MBTA closes down too early with its current hours.

"I think right now there's very little way to get home after midnight," Havern said.

Havern added that the MBTA's current hours are not well adapted to the needs of young people in the Boston area.

"We ought to be able to extend service to 2:30 on Thursday, Friday, and Saturday nights," he said.

Mulhern said the new program would be somethingsimilar to the Massachusetts TransportationAuthority's "night owl" program of the early1960s, as the bus service would supplement thesubway service on five to six heavily traveledroutes.

Mulhern stressed the move would help the MBTAmeet both its business and public-serviceresponsibilities.

The move will increase the MBTA's fiscallosses. Normally, the MBTA takes a $1.10 loss onevery bus trip. During the new late-night hours, asmaller number of passengers is expected to makethe per-passenger loss four times that.

In addition, the new program would also affectthe MBTA's ability to perform "criticalmaintenance" on the nation's oldest transitsystem, begun in 1897. Mulhern said that New Yorkand Chicago's public transportation systems offerlimited late-night service, but only on paralleltracks where they can run trains and performmaintenance at the same time.

Harvard students said they are pleased with thenew proposed hours-hours which will make the triphome from late-night events in downtown Bostoneasier.