Developers claimed the new racing track in Ebbw Vale would create thousands of new jobs.
Disruption for train passengers
Overrunning engineering works in the Cardiff area mean rail passengers are being advised to check before travelling.
Network Rail says there'll be disruption to services on the South Wales Mainline and on the Valley Lines at the start of service on Thursday morning.
A spokesperson said:
"We apologise for this disruption and would advise all passengers to check before they travel. Trains travelling to/from the east and north only will continue to start and terminate at Newport, as well as running between Swansea and Bridgend.
Arriva Trains Wales have provided standby buses across the South Wales region to keep customers moving.
We are doing all we can to reduce the disruption this causes today, complete the work and return services to normal as quickly and safely as possible - please check at nationalrail.co.uk for further information on delays to services before travelling."
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