The Intercounty Connector (Route 200) near Layhill Road. (Mark Gail/The Washington Post)

Motorists who use the Intercounty Connector have cut their drive times in half compared with those who use local east-west roads, which also are seeing lighter traffic, Maryland officials said Thursday.

Drivers who use the six-lane toll highway between the Interstate 270 corridor in Rockville and I-95 in Laurel save up to 25 minutes of travel time compared to taking local roads such as Routes 198, 28, 108, 650 (New Hampshire Avenue) and 115 (Muncaster Mill Road), according to the newly released study by the Washington Metropolitan Council of Governments.

Traffic on those local roads has dropped by five percent  to 10 percent since the ICC opened in November 2011, the three-year study found.

The $2.56 billion highway was mired in hot debate for decades over its cost and environmental impacts. Since the highway opened, some motorists  have complained that the tolls are too high, while others say it still has an empty feel much of the day.

The Maryland Transportation Authority, which operates the ICC, said Thursday that traffic volumes are in line with projections. About 40,000 vehicles use the ICC daily between I-370 and Georgia Avenue, while about 30,000 use it between U.S. 29 and I-95, the authority said.