Are you ready for a train ride on the Chartreuse Line?

Or a trip on the B Train? A journey on the No. 10? How about just a ride on the Paoli Line?

SEPTA is considering getting rid of the "R" train route designations it has used for 25 years. The system is confusing for infrequent riders and tourists, general manager Joseph Casey says, and needs to be replaced with something easier to understand.

But what?

Train lines could be designated by colors. Or final destination points. Or letters. Or numbers.

"We're trying to get input from riders and other stakeholders," Casey said after SEPTA officials made their pitch last week to city and county officials, passenger advocates, and others. "We're trying to make it easier to use the system."

Opponents of a name change, including top city transportation officials, worry that the new designations would be part of a broader plan to change the way SEPTA operates its trains. Such changes, they say, would undermine the integrated rail network created in 1984 when the Center City tunnel linked the old Pennsylvania and Reading rail lines.

SEPTA officials insist that only the names would change; operations would remain the same.

Currently, SEPTA's 13 train routes are labeled R1 through R8, except that there is no R4. And there are two different final destinations for each R route, except for the R1 line, the airport branch.

For instance, some R3 trains terminate at Media or Elwyn in Delaware County. Other R3s run to West Trenton. Regular commuters know the difference between the R3/Media-Elwyn line and the R3/West Trenton line, but SEPTA says passengers unfamiliar with the system can easily end up on the wrong train.

"We get hundreds of complaints each year from people who get on the wrong R5 or the wrong R7," said Byron S. Comati, director of strategic planning and analysis for SEPTA.

"There's pretty good agreement that the current system is confusing," said Matthew Mitchell of the Delaware Valley Association of Rail Passengers. "If you hang around a Center City station for 20 minutes, you'll see several people trying to figure out, 'What stairway is my train?'

"But there's no one right answer for what to use in place" of the R designators, Mitchell said.

One proposal is to return to the nomenclature used in pre-SEPTA days, when Philadelphia trains were operated by the Pennsylvania Railroad and the Reading Co. The routes were designated by their end points: the Chestnut Hill line, the Paoli line, the Trenton line.

That's also the system used by many other U.S. commuter rail operations, including those in New Jersey, New York City, and Chicago.

Other possibilities include using 13 separate letters or numbers to designate the routes, such as the A line and the B line, or the 10 line and the 12 line. Some have suggested using new R designators, from R1 to R13.

Or SEPTA could use 13 color names for the train routes.

The lines already have colors associated with them on SEPTA signs and printed schedules: green for the R6, red for the R7, and blue for the R5, for example. But more colors would be needed for both ends of the paired lines, and there could be confusion between SEPTA's subway and trolley color designations (the Broad Street Line is orange, the Market-Frankford Line is blue, and the Subway-Surface Lines are green).

The current R designations were created when SEPTA completed the Center City tunnel in 1984, connecting the former Pennsylvania and Reading systems. Instead of terminating at Suburban Station or the Reading Terminal, trains could operate through to the other end of the line. An R7 train could run from Trenton to Chestnut Hill East, for example.

But today, most rail trips don't run from one end of a line to the other. Only 33 percent of weekday trips are end-to-end runs, according to SEPTA.

Many trains go to Center City, then to a rail yard to be sent out on another line. And 19 percent change R designations as they leave Center City without stopping in a yard.

Luther Diggs, chief operations officer, said the proposed changes in route designations would not mean a change in the way trains operate.

"What we intended to do 25 years ago and what we actually did are two different things," Diggs said. "We're not changing anything from an operations standpoint."

But Christopher Zearfoss, the city's senior transportation project manager, said SEPTA could renumber routes without losing the concept of through service on the rail lines.

"The city sponsored the [Center City tunnel] project," Zearfoss said in an e-mail to SEPTA officials and others who attended last Wednesday's meeting. "Our federal and state grant applications justified the project, in part, on achieving 'continuous . . . fully integrated rail service . . . while enhancing the convenience and attractiveness of the system and improving accessibility.' Marginalizing the usefulness of through-[tunnel] travel seems to run counter to these representations made to our federal and state funding agencies."

He said nothing would eliminate all passenger confusion.

"To paraphrase the Bible, the confused rider you will have always with you," he wrote. "Despite best efforts, there is no foolproof firewall against those riders who are distracted, multi-tasking, hurried, agitated, or just plain careless; they will make mistakes. . . . But that is no pretext for discontinuing those important scheduling practices."

Zearfoss suggested assigning 13 separate R numbers to the rail lines, and having the "public timetables continue to highlight the fact that most trains on the two lines are combined and operate through the [Center City tunnel], thereby affording frequent 'suburb-to-suburb' service without change of trains."

Vukan R. Vuchic, a University of Pennsylvania transportation professor who was a creator of the R designation system 25 years ago, said SEPTA was making a big mistake in trying to get rid of it.

"It is already confusing for passengers, and SEPTA wants to give less information? What kind of logic is that?" Vuchic asked. "They just want the freedom to send their trains as it fits their needs, that's all they're concerned about."

Kim Scott Heinle, SEPTA assistant general manager for customer service, emphasized that no decision had been made on the R changes and that SEPTA wanted more input from passengers and other interested parties.

"This is a customer-service initiative," Heinle said. "It's all about improving our ability to attract new people to the system. We truly believe that there are a number of folks that get into the system and go where they don't want to go."

In a change expected to attract less concern, SEPTA also plans to do away with the Route 100 designation for the rail line that runs between Norristown and 69th Street Terminal in Upper Darby. SEPTA will call it simply the Norristown High-Speed Line, beginning in September.

Some passengers still refer to that line as the P&W, in reference to its pre-SEPTA origins as the Philadelphia & Western Railroad.

SEPTA officials also plan to color-code all trolley lines green, including the current Green Line subway-surface trolleys in West Philadelphia, the Routes 101 and 102 trolleys that run from 69th Street Terminal to Media and Sharon Hill, and the Route 15 trolley that runs along Girard Avenue.