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The Welsh Christmas getaway has started, with experts predicting Wednesday evening's rush hour would be the busiest of the festive period.

The M4 around Newport, especially going westbound into Wales, was due to hit its festive pinch point at about 17:00 GMT, according to traffic analysts.

Major engineering work on the railways will affect Welsh trains to and from London, Portsmouth and Cheltenham.

Rail passengers are urged to travel early and to check their journey.

Roads

Roads are expected to be busier than usual for the rest of the week as drivers try to beat the weekend rush ahead of Christmas Day on Tuesday, according to traffic data firm Inrix.

Experts have warned the M4 westbound between the Prince of Wales bridge and the A48M junction just outside Cardiff will be Wales' busiest stretch of road over the festive period.

Inrix predicted congestion would be almost twice as long as normal around Newport and through the M4's daily Brynglas Tunnels bottleneck at 17:00 on Wednesday.

They said people heading for their Christmas getaway would be travelling about the same time as commuters at evening rush hour, meaning journeys would take 17 minutes longer or be 77% busier than usual.

Inrix said Thursday's congestion would be "a close second".

"Our data suggests the traffic starts earlier on the Thursday, which suggests that commuters are taking the Friday off work and leaving midday Thursday," a spokesman said.

Media playback is unsupported on your device Media caption How do you avoid holiday traffic jams?

"Since people left throughout the day on Thursday the congestion lasted longer, but didn't reach the same peak as Wednesday when commuters all left work at the same time and merged with rush-hour traffic."

Rail

Train travel between Wales and London will be disrupted from this weekend until the new year because of engineering work.

Passengers from north Wales will be affected as Virgin trains to and from Holyhead and Wrexham will not run on Christmas Eve, 27 December and 30 December due to work at Euston station.

The Holyhead services will end and start at Crewe.

Travellers going between south Wales and London have been warned of problems as Paddington station will be shut on 23 December, Christmas Eve and New Year's Day as Network Rail does a £25m upgrade.

Also, there will be no direct trains between south Wales and London and Portsmouth between Christmas and new year due to work to electrify the line around Severn Tunnel Junction.

Buses will replace trains between Newport and Bristol while there will be an amended timetable either side of the closure.

Passengers travelling between south Wales and Portsmouth over the festive period will also have to use a replacement bus between Trowbridge and Warminster because of work.

Image caption The Severn Tunnel will shut between Christmas and the new year for electrification work

Due to the work around the Severn Tunnel, trains between Cardiff and Taunton will only operate between Taunton and Bristol Temple Meads.

Rail passengers travelling between Cardiff and Cheltenham face disruption on 27 and 28 December as the service will start and end at Newport instead of Cardiff.

Work will also affect Valley Lines services in and out of Cardiff over Christmas.

Trains between Treherbert and Cardiff on 27 and 28 December will start and end at Cardiff Bay, rather than Cardiff Central, because of engineering work.

Also on those dates, while there will be a reduced timetable for services between Cardiff Central and Penarth and Bargoed.

There will be no train services on Cardiff Valley lines on New Years Day - except an hourly service between Cardiff Central and Bridgend via Llantwit Major in the Vale of Glamorgan.

No trains are running on Christmas Day or Boxing Day but nationwide bus companies National Express and Mega Bus are operating.

Air

Cardiff Airport is expecting 32,000 passengers in its busiest holiday season since 2010.

Passengers number were up 8% on last year with Amsterdam, Dublin and Edinburgh the most popular destinations.