M4 relief road overspend would have 'public/private split'
Any overspend on the proposed £1.1bn M4 relief road around Newport would be split between public and private bodies, an inquiry heard on Friday.
Construction expert Barry Woodman said the same arrangement was in place if the motorway came in under budget.
He told the Newport hearing it would be a "50/50 split" between the Welsh Government and construction firms.
The Welsh Government wants to build a six-lane motorway south of Newport as the M4 is "not fit for purpose".
Until the deal is approved, companies involved are being paid an hourly rate, Mr Woodman said.
If the scheme gets the go-ahead, a budget figure will be set.
Mr Woodman also said the project presented "a real opportunity for training and development of apprentices".
The inquiry is due to last five months and will examine the plan and alternatives as the Welsh Government wants to relieve congestion on the current M4 around the Brynglas tunnels.