Edinburgh trams chief leaves troubled project

• Quitting: David Mackay

He also launched an outspoken attack on the tram project, describing it as "hell on wheels".

A respected transport figure, Mr Mackay claims in an exclusive interview with The Scotsman today that a Scottish-based firm may have made a better job of the project than German outfit Bilfinger Berger, currently involved in a bitter contract dispute with the trams company.

He said: "Bilfinger Berger was a delinquent contractor who scented a victim, who probably greatly underbid and who would use the contract to make life extremely difficult for the city. And they have done exactly that."

On major problems encountered during the project, he said: "We had found crazy things like underground chambers on Princes Street and cables were not where they should be … It was hell on wheels."

Mr Mackay's decision to quit will plunge the scheme - currently stalled due to the dispute with Bilfinger Berger - into renewed crisis: no-one has yet been lined up to replace him.

It also comes at a crucial time for city council-owned tram developer Tie, which is weeks away from the expected termination of its contract with the construction consortium.

Mr Mackay has also resigned as chairman of bus-tram co-ordinating body Transport Edinburgh. He has been chairman of council-owned Lothian Buses since January.

• What went wrong: 'It's hell on wheels' - the inside track on tram fiasco

It comes as yet another blow to Tie and its operating company, Edinburgh Trams, which has appointed three chief executives since it was established.

Mr Mackay's decision to go, despite Tie urging him to stay, follows a series of setbacks and acrimonious rows with Bilfinger over completion of the 11.5-mile Edinburgh airport-Newhaven line, which are now almost certain to end in litigation.

The project is thought likely to far exceed its 545 million budget, with the latest expected opening date of 2013 also in considerable doubt.

However, Tie stressed Mr Mackay's move was an entirely personal decision and there were no hidden factors. One insider said: "There is nothing sinister."

Mr Mackay indicated the council had known of his intentions for some time.

The Scotsman understands the catalyst for his departure was him completing key appointments at Transport Edinburgh: of Tie chief executive Richard Jeffrey in the same role there, and of Lothian Buses' managing director Ian Craig as its chief operating officer.

What will surprise many is less the decision to quit - Mr Mackay is 67 and has faced a series of trams crises that have bedevilled the heart of Scotland's capital - than the news he will be going with immediate effect, rather than staying three to six months to see in a successor.In a wide-ranging, exclusive interview, he said: "I believe there comes an important juncture when the most powerful action you can take is to pass the controls to a successor and to then watch that organisation develop further under a new champion.

"I felt a clean break was better. It will not be a bolt out of the blue for the city council, and I am not leaving under any cloud.

"Although the council might be disappointed, I don't think it will be surprised.

"It will be an opportunity for the project to re-engage and replenish. The project has been an enormously absorbing one and as such there was never going to be an entirely ideal time to step aside.

"The time has now come when it is appropriate for me to move on, which should allow me to refocus my energies on to a better, and probably much overdue, calmer work/life balance."

The Scotsman understands separate interim chairs will be appointed for Tie and Lothian Buses until a joint successor is found. This is seen as important in underlining their separate operating structures after fears the bus firm could be asset-stripped to cover initial tram losses.

Mr Mackay has been chairman of Transport Edinburgh since 2006 and became Tie chairman in December 2008 after the unexpected resignation of Willie Gallagher. He oversaw major changes and brought in former Edinburgh airport chief Richard Jeffrey as chief executive.

Council leader Jenny Dawe said: "I was aware that we were unlikely to retain David until full project delivery, and fully appreciate his reasons for standing down at this point."

Transport convener Gordon Mackenzie said: "David has been a critical figure in ensuring we get best value for the public purse, and has been a formidable chairman on our behalf throughout the negotiations with our contractors."