SEPTA MAY be forced to eliminate service on nine of its 13 rail lines, shorten two other lines, scrap express subway service and convert all trolley routes to bus routes by 2023 without an infusion of funding from the state, the agency's general manager said yesterday as he outlined a doomsday plan.

Testifying before the state Senate Transportation Committee in a hearing at Temple University, SEPTA general manager Joe Casey said the plan would begin next year and eventually reduce daily rail ridership by 12 percent.

SEPTA ridership is at its highest in more than two decades.

Casey said the draconian cuts would be the result of a failure to address immediate needs across the system, such as replacing bridges that are more than 100 years old, and purchasing new rail, subway and trolley cars.

He said the agency needs $6.5 billion over the next 10 years to bring it to a "state of good repair." Without it, he said, SEPTA would end service on the Cynwyd line in 2014, the Media/Elwyn line in 2015 and the Chestnut Hill West line in 2018. Six more lines would be eliminated or shortened by 2023. Under the plan, SEPTA would also get rid of the Broad-Ridge Spur subway and all express subway service.

After debating three plans to increase funding for bridges and mass transit this year, state lawmakers whiffed on all three before summer recess.

Under a $2.5 billion plan passed by the Senate, motorist fees and traffic fines would increase, and the cap on the oil-franchise tax would be lifted.

On Twitter: @ChroniclesofSol