Vehicles approaching Britain's first motorway toll on the M6 in Staffordshire Credit: Rui Vieira/PA Wire
It will become the second toll road in Britain - following the M6 in Staffordshire - and will run between junctions 23 and 29 of the M4 to relieve congestion on the outskirts of Newport.
The newspaper reports that the Chancellor will agree to guarantee loans for the building of the M4 relief road, but the devolved Welsh government will meet the cost - expected to be around £830 million.
This cost will be recouped at least partly through tolls. While the price of tolls is not known, the longer M6 Toll currently charges £5.50 for a car and £11 for a lorry on weekdays.
Traffic is easing and visibility has returned to normal on the M4 Eastbound between J47 A48 / A483 (Penllergaer/Swansea West Services) and J46 A48 / B4489 (Llangyfelach).
An accident just after 3am in the Brynglas Tunnel means it's closed Eastbound between Tredegar Park and the Grove Park Roundabout, that's Junctions 28 to 25A.
Traffic's queueing for two miles back to the A48M.
There's already heavy traffic on the diversion route: via the A48 Southern Distributor road, to rejoin the Eastbound M4 at J24.
An accident in the Brynglas Tunnel has closed the M4 Eastbound between Malpas Road and the Newport/Grove Park Roundabout, that's between Junctions 26 and 25A.
It happened just after 3am and is thought to involve a single vehicle.
Police say they hope to re-open the carriageway at 9am.
There's a diversion onto the A48 Southern Distributor, over the bridge in Newport and back up to rejoin the M4 at J24.