The National Audit Office reported on Friday that final costs on the scheme could reach £88Bn – 53% over available funding. The Department for Transport and High Speed 2 underestimated the complexity of the project and have failed to adequately manage risks to taxpayer money, it said.

It added that full services on the entire network from London to Birmingham and on to Manchester and Leeds are now forecast to start between 2036 and 2040, three to seven years late.

The Government is shortly expected to make a decision on the future of High Speed 2, following release of the yet to be published Oakervee review of the project.

Campaign organisation the High Speed Rail Group called on the Government to “get HS2 done” and described the scheme as essential to the aim of ‘levelling up’ the economy and fixing the north – south divide.

A spokesman said: “HS2 is the only ‘shovel ready’ project of its scale in Britain today. If the Government wants to fulfil its promise of an infrastructure revolution, HS2 must be completed in full, without further dither and delay.”

CIHT’s chief executive Sue Percy said the Institution believes High Speed 2 offers significant benefits for capacity, connectivity and the economy, if delivered in an appropriate manner.

“It is clear however, that HS2 is proving to be a divisive issue and more needs to be done to demonstrate the benefits that the project could deliver, including wider regeneration and investment opportunities and the levelling up of the economy,” she said.

Sue added that greater certainty over timing and costs on the project would help to ensure the support of more stakeholders. For more detailed commentary from CIHT, please see here

The National Audit Office report says that the Department for Transport and High Speed 2 have made progress with their preparations for starting construction on Phase One of the project. But they will need to manage risks that could cause costs to further increase.

Law firm Clyde & Co’s partner Mary Anne Roff commented that successful delivery of construction projects “is all about getting the balance right between time, cost and quality and ensuring a proper balance of risk between the parties across those factors”.

“When one element is pushed out of kilter – for example, the start date is delayed and the programme is pushed back – that delicate balance can start to unravel,” she said.

“If further procrastination over HS2 pushes back the start of the next phase of works, the agreed programme will be in delay before it has even begun.”

National Audit Office head Gareth Davies concluded: “To ensure public trust, the Department and High Speed 2 must be transparent and provide realistic assessments of costs and completion dates as the programme develops, recognising the many risks to the successful delivery of the railway.”

A Department for Transport spokesman said: “We recognise that there have been significant underestimations of both the cost and schedule of HS2 in the past which is why we commissioned the Oakervee review to provide advice on whether and how to proceed with HS2.”

A High Speed 2 spokesman said that the project’s chief executive Mark Thurston identified “the serious challenges of complexity and risk in the project, and made several significant changes and improvements to the organisation, its governance and processes,” following his appointment in 2017.

The spokesman added: “If the Government decides to proceed, High Speed 2 has a highly skilled team in place ready to build Britain’s new state of the art, low carbon railway.”

(Image: Grimshaw Architects)