The D Line doesn’t serve Five Points anymore, but you can still get there on the “new” L Line, which began service on Sunday. Why split the old D service in two? RTD says it will improve reliability, especially downtown.

The L line follows a 1.7-mile route between the 16th Street Mall stations and 30th and Downing, with trains coming every 15 minutes until about 7:30 pm when frequency falls to 30 minutes.

Passengers now have to transfer if they’re traveling between the northern terminus at 30th and Downing and stations south of 16th Street, and can expect to wait three to six minutes between trains. The new service pattern is expected to improve reliability systemwide, however, by eliminating delays that rippled out from a one-track segment on Welton Street at 24th Street.

In the old service pattern, northbound D trains would have to wait for southbound D trains to clear the one-track segment before proceeding. That led to delays for other trains on the loop behind the waiting D train, and that would delay even more trains south of the loop.

With the shorter, simpler L Line service pattern, RTD can more easily time northbound L trains to avoid waiting for an opening at the one-track bottleneck.

“The point is to try to make it more reliable so you actually know what time you’re gonna be getting off this train, transferring, and getting back on,” said Eric Miller, a rail service planner with RTD. “On the old D Line, sure, you had a one-seat ride. But you may make it to 30th and Downing at this time or you may be seven or eight minutes later.”

The adjustment has another positive effect, Miller says. The comparatively low ridership on the L Line lets RTD add a car to each D train (they’re now four-car trains).

RTD has plans to extend the L Line up Downing Street, where it will connect with the A Line at 38th and Blake. The .8-mile extension will fill a critical link in the intra-city rail network — but like so many RTD projects, the transit agency doesn’t have money to build it, even though it’s been on the books since voters passed the FasTracks legislation in 2004.