Negotiators for SEPTA and Regional Rail locomotive engineers reached a tentative agreement, which will avert a possible commuter rail strike if the pact is accepted by the engineers and the SEPTA board.

The deal provides for SEPTA's 220 engineers to get an 8.5 percent wage increase when the contract is approved and a 3 percent raise next April.

The engineers, who have not received a raise since their last contract ended in 2010, also will get a $1,250 "signing bonus" and a 35-cent-an-hour increase immediately to reflect a traditional differential above conductors' pay. All together, the engineers' increases will amount to 13.3 percent above current pay by April, the union said.

"This agreement keeps the trains rolling in Philadelphia," said Steve Bruno, national vice president of the Brotherhood of Locomotive Engineers and Trainmen and a lead negotiator for the SEPTA engineers.

SEPTA officials said they were "pleased" the tentative agreement had been reached.

The engineers, along with railroad electrical workers, went on a one-day strike in June but were required to return to work when President Obama named a mediation panel to try to settle the long-running dispute. That panel issued recommendations in July largely supporting SEPTA's position, and those terms formed the basis of Monday's agreement. Obama named a second panel, effective Monday, after the term of the first one expired.

The engineers said they were prepared to strike again in February, when the second presidential board's term expires, if an agreement was not reached. That raised the prospect of a coordinated strike with unions representing bus drivers and subway and trolley operators, who are also without new contracts and in ongoing negotiations with SEPTA.

Such a coordinated action could have meant the first complete shutdown of all SEPTA service in the transit agency's 50-year history.

Under the tentative agreement reached Monday, the top wage rate for engineers would increase by $4 per hour, to $34.10 an hour by next April. Engineers, who typically work six-day weeks, now earn an average of $95,290 a year, SEPTA said.

About 126,000 passengers ride SEPTA commuter trains daily.

SEPTA agreed to drop its demand that engineers wear uniforms, which had been one of the points of contention in the talks.

The engineers said they would continue to press for changes in safety procedures outside the contract talks.

Bruno praised the tentative agreement as "a compromise on economic issues." He said union complaints about long work days and six-day weeks for engineers will be taken to the Federal Railroad Administration.

The tentative contract, which covers the period since the last term ended in 2010, would end in July 2015. That means negotiations for the next contract will begin almost immediately.

Results of the ratification vote by the union members are to be announced within 30 days, and SEPTA's board has empowered its chairman, Pasquale "Pat" Deon Sr., to approve the contract on the board's behalf.

A final agreement with the locomotive engineers would assure SEPTA that its commuter trains would keep running even if buses, subways, and trolleys were shut down by a transit workers' strike later this year or early next year.

Transport Workers Union Local 234, which represents those workers, is scheduled to resume negotiations Tuesday with SEPTA officials. The TWU workers' contracts expired in March and April, and the workers could go on strike with short notice.

The TWU is the largest of the 17 unions representing SEPTA workers, and its contract typically sets the pattern for settlements with the other unions.