BOSTON — The new all-electronic tolling system along the Massachusetts Turnpike is trimming some commute times, state transportation officials say.

Drivers traveling east along the highway from the Interstate 495 junction to South Boston saw up to 12 minutes of travel-time savings on average since the system went live in late October, the state Transportation Department said in a Wednesday news release.

The gantries that span the highway electronically gathering tolls have registered more than 50 million transactions as of Dec. 4.

Efforts to get motorists to use E-ZPass transponders have also been successful, with more than 3 million now in circulation in the state. About 86 percent of toll transactions have been via transponder, above the agency's goal of 85 percent.

"The transition to all-electronic tolling has been a smooth one, and we believe the public has started to realize the goals of the program which include increasing safety, some relief from traffic congestion and a reduction in greenhouse gases," Transportation Secretary Stephanie Pollack said.

Toll booth demolition and roadway reconstruction continues on schedule at 23 work areas.

Early demolition work at the former toll plazas was completed ahead of schedule in time for Thanksgiving travel, which reportedly saw less severe congestion than previously.

Drivers without transponders are billed by mail for their tolls, but they pay more.