It is appropriate that the progress in building a railroad is similar to that of a railroad locomotive itself. A train moves so slowly at the beginning that an impatient passenger can be forgiven for thinking the thing is never going to get out of the station.

But the train eventually begins picking up speed, and at some almost imperceptible point the passenger realizes he is on his way.

If things go according to plan, that “We’re off!” moment will come in May for the Denton County Transportation Authority. That’s when the DCTA hopes to award a contract for a dozen diesel-powered railroad vehicles that will move passengers along its Denton-to-Carrollton line sometime after the road is completed in 2010. The bidding process will begin next month.

The DCTA has set aside $71 million for the 12 commuter-rail vehicles, and there will be some suspense to see which, if any, bids come in at or under that estimate. The DCTA’s specifications call for the vehicles to have the capability of running on electrified as well as non-electrified rails, and to be manufactured with the latest fuel-efficient and sound-dampening technology. The money is coming from the DCTA’s own coffers and from the Regional Transportation Council.

Scott Neeley, the DCTA’s chief operating officer, sounded like a kid with a new electric train when he talked about this latest development in a story in Friday’s paper.

“This is huge,” he told the Record-Chronicle’s Dan X. McGraw. “It sets the stage for the rest of our rail project. This puts us down that track.”

We don’t know if Neeley was purposefully using the railroad imagery or if it just comes to him naturally, but we liked it, and we think it’s fitting that the biggest and most visible step yet in the agency’s long journey toward establishing rail transportation for Denton County residents should be couched in terms of moving “down that track.”

Denton County voters in three towns took courageous and far-seeing action back in 2003 when they voted to tax themselves to finance a county-wide bus and rail system that would eventually link Denton and Dallas counties. DCTA buses are already providing much-needed transportation services throughout much of the county, and now we can actually begin to see the day when a quiet, fuel-efficient commuter train will depart from Denton and end up at the Dallas Area Rapid Transit green line station in Carrollton.

The train isn’t up to speed yet, or even moving. But with last week’s news, we’ve felt that first “bump” — the traditional and quietly exciting signal that the trip is about to get under way.