BRITS are facing long delays as a busy motorway has closed with a huge diversion in place.
A major resurfacing project of the M4 started last night, and is set to last for four months.
The closures will start at 8pm and last until 6am, to reduce disruption to drivers.
The westbound carriageway will close tonight, between between junctions 17 and 18. A diversion will be in place via the A350, A420 and A46.
The closures will remain in place over the coming weeks.
A spokesperson for National Highways said: "There will be weeknight lane closures on the M4 westbound between junctions 17 and 18 between 8pm and 6am, at least one lane will remain open in each direction.
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"The junction 18 westbound exit slip will also be closed weeknights from Tuesday 20 to Tuesday 27 August. Please follow signed diversion.
"We’ll then work our way along the carriageway and slips roads using full and lane closures. Check back for details of upcoming closures as our work progresses."
New research reveals that 53,000 smart motorway users have been caught illegally entering or passing in a lane under a red X.
Drivers can face fines of up to £100 and receive three penalty points for this offence.
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In some cases, more severe penalties and even court appearances may occur.
Figures from show that 4,393 incidents were recorded in 2021, 20,773 in 2022, and a staggering 28,231 in 2023.
Obeying red X signs is vital for safety on smart motorways, where the hard shoulder has been converted into a live running lane.
National Highways activate the closed lane signs when a stopped vehicle is detected in live lanes to prevent collisions and to protect emergency services.
Smart motorways were introduced by the coalition government in 2014 with the intention of speeding up the flow of traffic.
But they were removed from government road-building plans in 2023 due to the lack of confidence felt by drivers and financial pressures.
A National Highways spokesperson said: “A Red X signal is there to increase the safety of everyone using the road by highlighting an issue ahead.
“Above 90% of drivers observe Red X signals, but ignoring Red X signals is an offence and puts themselves and others at risk.”