There’s something old and something new under consideration by the Triangle’s Special Transit Advisory Commission (STAC).

The old: The commuter rail line as it was first envisioned some 20 years ago to run from Chapel Hill to Durham to Cary to Raleigh, with small changes. The new: Four electrified streetcar lines that would link to the rail linea total of 56 miles of streetcars. They’d run downtown in Durham; across town in Chapel Hill-Carrboro; around town in Raleigh; and around a loop in the center of the Triangle, from RTP to the airport to Brier Creek.

In addition to the old and the new, there would also be borrowing. The region’s transportation planners are guesstimating the cost of building all thisalmost 60 miles of commuter rail plus the streetcarsat $3.5 billion to $4.7 billion.

Add another $3 billion or so, and the original rail line could grow spurs to the west (to Hillsborough and then Burlington), the south (to Apex, Fuquay-Varina and Selma), the east (to Zebulon and maybe Wilson) and the north (to Franklinton and Rougemont). That would be almost 240 miles of commuter rail (plus the 56 miles of streetcars) at a rough cost of $6.1 billion to $8.2 billion. All would follow existing rail beds, minimizing land-acquisition costs and maximizing the future potential for dense, transit-oriented development (TOD, as it’s known) in areas that are now essentially rural.

The “best of the rest,” using 120 miles of commuter rail, would cost between $4.8 billion and $6.6 billion. But only the first 60 miles is considered transit-ready or nearly ready, with enough people living or working within half a mile, the planners say.

So is this just blue-sky stuff? Or what the STAC is likely to recommend as it nears the end of its six-month study of the region’s transit needs? That was the question STAC members were asking each other in whispered conversations Mondayand one asked aloudafter they heard the presentation by the commission’s staff. Jennifer Lewis is a Sierra Club representative and a transportation planner for a private firm. “I’m having trouble understanding where we are” in the decision-making process, she told Phil Boyle, the facilitator. What are the “parameters” for deciding what to recommend? she asked.

“Your question is, What are the questions?” Boyle quipped.

The STAC’s 29 members were appointed by the region’s two transportation planning agenciesgroups comprised of elected officials widely dispersed across the eastern and western portions of the regionto address the failure last year of the Triangle Transportation Authority’s (TTA) application for federal funds to start building the first 28 miles of rail.

The STAC’s job: Pull the sled out of the ditch and come to a consensus on “the major transit investments” that the region should make over the next 25 to 30 years. It’s been meeting since May.

If the outcome of the group’s charge is in doubt, however, the issues it confronts became clearer just as soon as the planners put something on the table this week for them to shoot at. That was the point, said Mark Ahrendsen, chief planner for DCHC (Durham-Chapel Hill-Carrboro), one of the two planning agencies (CAMPO, short for Capital Area Metropolitan Planning Organization, is the other). “It was time and important to get some lines on a map,” Ahrendsen said.

Where to start? The TTA plan would’ve started with a main rail line connecting downtown Durham to downtown Raleigh, a project with an $800 million price tag. All the chips were on itbecause it was never clear what would come next. So when the plan failed, it left a huge void. Alternatively, said Ed Johnson, CAMPO’s chief planner, you could start small with the streetcar “hubs”or portions thereofand build the big rail “spoke(s)” later. Chapel Hill expects to finish a plan for its streetcar system by the end of the year, said David Bonk, the town’s transportation expert. Raleigh’s system could start with a single line up Hillsborough Street, a pet idea of the city’s planning director, Mitch Silver, and gradually expand as funds become available.

How farsighted to be? Very, said Smedes York, a developer and former Raleigh mayor, one of the STAC’s two vice-chairs. York pushed for the rail scenarios to be released first, not because they’re the only approach, he said, or even necessarily the best one. But they’re “exciting” to envision, York said, and the streetcars “add a little excitement.” The cost figures are big, he acknowledged, but it’s not like all the money would be spent right away. “It’s a very big region,” he added, “and to be world-class we’ve got to make major investments over timeand there’s a huge population base that those investments will be related to.”

“Everyone now realizes that the success of the Triangle area depends on getting away from auto-dependent modes of travel,” said George Cianciolo, a Chapel Hill planning board member and STAC co-chair.

But not too farsighted? “This is a 2035 plan?” asked Sandy Ogburn, a former Durham City Council member. “We have to figure out how to do this in segments.” Chris Harder, vice chair of Durham’s transit system, agreed: “Choose a smaller-scale start to show success. Then people will say, ‘Yeah, I want that.’”

Is this one system or a hybrid? “Touchy subject,” Johnson says. And not clear at all. Would Chapel Hill’s bus system, for example, also run the local streetcars? And pay for them? Or would the TTA?

Pay for them how? There’s talk in Washington of a new transit funding category called “Small Starts.” The name speaks for itself. Think streetcars. The TTA rail project spent a decade in the federal “New Starts” queue, and drew down about $100 million from Washington, before it was turned away short of the finish line.

How about buses? They are on tap for discussion at the next meeting on Sept. 27.