Work began at 6am today to remove 27 toll booths on the southern end of the Dartford Crossing.
The booths on Britain's busiest motorway are being scrapped and replaced with an electronic payment system.
The changes at the Dartford Crossing on the M25 east of London are designed to improve traffic flow.
But the removal of the 27 toll booths at the southern end of the crossing will result in roadworks until March 2015.
And car drivers using the crossing will from today face a higher daily charge - with the fee, also payable by phone or post as well as online, going up from £2 to £2.50. Charges are also rising for goods vehicles.
The Highways Agency is hoping for a minimum of congestion at the start of the new system.
An agency spokesman said: "We're starting at 6am on a Sunday when traffic will be comparatively light and there will be plenty of signs up to tell people about the new arrangement.
"Monday morning will be more of a test but we are trying to do everything we can to let people know about the changes."