The transport secretary has opened the UK's first motorway car share lane.
Ruth Kelly said the extra lane would benefit commuters in Leeds and Bradford, helping them to cut journey times and reduce their carbon footprints.
The 1.7 mile lane links the southbound M606 near Bradford to the eastbound M62 near Leeds, a notoriously congested junction.
Any car with more than one occupant will be allowed to use the lane, alongside buses, taxies and motorcycles. West Yorkshire police will enforce compliance.
Government research found four out of five vehicles using the junction only have one occupant and Ms Kelly said she hoped the lane would encourage more people to share their journeys.
This "will ease congestion, cut journey times and improve local air quality," she said.
Ms Kelly continued: "The government is committed to finding innovative ways to get more from our existing roads and improving journeys for motorists.
"We have identified around 500 miles of motorway as potential priority sites for new traffic management measures, which may also include more car share lanes."
Car share lanes are common in America but are yet to take-off in the UK.
The AA welcomed today's initiative but questioned whether it would encourage more people to car pool.
Edmund King, president of the AA, said: "Any extra road capacity added to motorway pinch points is welcome.
"We will watch the use of the car share lane with interest. Experience in the USA suggests that many high occupancy vehicle (HOV) lanes are under-used and therefore a waste of capacity.
"It is likely that many people who already car share will benefit but unlikely that such a short stretch will tempt many potential car sharers out of the driving seat."
The AA argues the extra lane, which has been built on the hard shoulder, should be opened to all vehicles if it is underused after six months.