Abandoning HS2 for cheaper alternatives would result in "14 years of weekend disruption"

The report by Network Rail and Atkins, an engineering consultancy, is to be published tomorrow as part of the Government's revised business case for the proposed national high speed rail network, according to the BBC. It concludes that there would be 14 years of weekend route closures and longer journeys on the East Coast, West Coast and Midlands main lines if the Government cancels its plans for the controversial line.

Infrastructure law expert Chris Hallam of Pinsent Masons, the law firm behind Out-Law.com, said that the report was "further evidence" that the need for the new route was "founded upon capacity and growth as much as - if not more than - speed".

"The alternative to HS2 is a 'patch up' job on the existing main lines," he said. "It will cost almost half as much as HS2, but provide only 40% of the extra capacity that HS2 would create and will result in 14 years of chaos for passengers. Anyone who remembers the problems and inconvenience caused when the West Coast Main Line was upgraded a few years back will shudder at the thought of further disruption on this scale."

"The £43 billion construction cost of HS2 works out to less than £2bn a year over the duration of the project," he said.

The Network Rail report will show that simultaneous upgrades to the UK's three existing main rail lines would require 144,000 hours of work and 2,770 weekend closures, with limited opportunity to divert traffic along other routes, according to the BBC. These closures would double journey times between London and Leeds to more than four and a half hours while the work was going on, the BBC said.

The report will also conclude that residential and commercial demolitions would not be avoided by upgrading existing lines rather than constructing a new one, according to the BBC's coverage.

HS2 is due to be delivered in two phases, with the initial London to Birmingham phase of the line scheduled for completion in 2026. The line will cut journey times between the two cities to 45 minutes and support trains running at up to 250 miles per hour, according to the Department for Transport (DfT). A proposed second phase of the project envisages the construction of an onward 'y network' connecting the line to Manchester and Leeds, as well as to Heathrow Airport, by 2033.

The project continues to have the support of the leaders of England's three main political parties; however, at the recent Labour Party Conference, Shadow Chancellor Ed Balls said that a future Labour government would not support the line if costs continued to rise. According to the latest estimates, the project is expected to cost £46.2bn with an additional £7.5bn for rolling stock; a budget that Treasury Secretary Danny Alexander told the Andrew Marr show this weekend that he was "confident" the project would meet.

The DfT is due to publish an updated business case for HS2 on Tuesday, two days before the third reading of the so-called 'Paving Bill' in the House of Commons. The document will respond to the conclusions of a highly critical report from public spending watchdog the National Audit Office (NAO) in May, which found that the Government had not yet demonstrated a "clear business case" for the project. The Treasury Committee reiterated these concerns earlier this month, calling for a "formal reassessment" of the benefits of the new line in relation to its costs.

In September HS2 Ltd, the company set up to deliver the project, responded to the NAO's concerns about the ability of the new line to stimulate regional economic growth with its own report commissioned from analysts KPMG. This report highlighted £15bn of productivity benefits across the regions, but omitted figures showing that areas such as Aberdeen, Bristol and Cardiff would in fact be disadvantaged by the new line.