THE controversial Pedestrian Heart scheme in Darlington town centre is now running at £2m over its original budget, council leaders admitted this week.

Darlington Borough Council admitted the project, which was originally budgeted at £6.5m, would rise to a minimum of £8.47m, after a series of "unforeseen and avoidable" errors.

The cost of pedestrianisation could rise further still to £9.2m, after the council assigned another £750,000 to cover any further unplanned costs.

Ada Burns, chief executive of the council, said on Wednesday that the project - originally due to be completed by Christmas - would run until late summer in 2007.

The project was originally delayed by up to six months, and an extra £640,000 cost was incurred, when workmen hit an undetected town centre gas main causing "significant" disruption to the project, particularly on High Row.

But in a report given to councillors yesterday, the council admits it had been forced to assign an extra £1.328m in their budget because of:

* failure to realise how complex the scheme would be, and a series of avoidable design faults which "didn't really work in reality";

* taking a "rolling train" approach to construction work, with up to 12 areas being worked on at one time - but with ineffective results;

* having to change plans after liaison with town centre businesses and bus operators to cater for their needs, and poor planning about the times town centre roads would need to be open;

* significant changes and disruption to original plans after the gas main was hit;

* "poor and unsatisfactory" project management by company Gillespies, resulting in the council appointing a different company midway through construction;

* a 90/10 partnership arrangement with contractor Birse which left the council bearing the vast majority of the financial risk.

Ms Burns pledged that the council had learned lessons from the Pedestrian Heart scheme - which is also partially-funded by regional development agency One NorthEast - and said that she had begun a review of how the authority's capital projects were managed from beginning to end.

Coun John Williams, leader of the Labour-led Darlington Borough Council, called for a full investigation into the Pedestrian Heart, saying the project had "not been managed well".

Coun Tony Richmond, leader of the Tory opposition, branded the management of the project an "absolute disgrace," and called for the resignation of the whole Labour cabinet.

"This news adds to the catalogue of disasters coming out of the town hall," he said. "What we have got here is something that has caused immense disruption to a lot of businesses, and to cap it all, there could be an increase of 32pc in the cost. Where will it end?"

Businesses across Darlington have campaigned against the project from its outset last year, claiming it has affected trade and decreased footfall in the town, and the town's Civic Trust group collected a petition with 4,600 names against the development.

Market trader Robin Blair said the extra delays to the project were potentially devastating for small businesses.

"Customers are heartily sick of this scheme, and they are working on so many sites at one time that it makes it very, very difficult to get round the town," he said.

But John Buxton, the council's director of development and environment, maintained that the Pedestrian Heart would be beneficial for Darlington when it was completed, despite the setbacks.

"It is making good process in large parts of the town, and we are confident that people will be happy with it when it is completed," he said. "Of course, we are disappointed with what has happened, but this is a high quality project that will make Darlington a 21st century shopping centre."