The government's infrastructure tsar has raised the prospect of the cost of High Speed 2 rocketing further after suggesting an extra £43bn of funding is needed to ensure people can make the most of the scheme.
Sir John Armitt, chair of the National Infrastructure Commission, said more investment was needed to prevent users of the new line encountering “inadequate public transport links" around major stations.
The additional funding would take spending on HS2 to £99bn - three times the original 2013 estimate of £33bn and close to double the current forecast.
The scheme is currently due to cost £56bn but a recent Cabinet Office assessment said it was “highly likely” to cost at least 60 per cent more, taking the total to more than £80bn.
Sir John's calls prompted demands that minsters "re-evaluate" whether HS2 will deliver value fo taxpayers' money.
HS2 involves the construction of 330 miles of new track linking London, the West Midlands, Manchester and Leeds.
However, fears have been raised about the lack of connectivity in areas with stations on the line. The increased number of passengers resulting from the new line is expected to put pressure on bus, tram and local train services in a number of towns and cities.
Writing in the Sunday Telegraph, Sir John said the government and local councils needed to stump up further money "to get the biggest bang for our buck".
He wrote: "HS2 is the most significant investment in the capacity and connectivity of our transport networks for a generation or more. The potential impact could extend 100 years or more, and its upfront costs should be considered in that context.
"But this also means we cannot simply construct a new high speed rail line and leave it at that: to get the biggest bang for our buck we need to think about the whole journey."
Highlighting the need to “make the most of this opportunity”, he called on ministers to “provide increased funding for cities” and “agree significant new funding for major infrastructure programmes in the fastest growing and most congested cities”, including new trams and bus networks.
He said: “All this would mean the UK’s cities outside London receiving a £43bn boost in funding up to 2040."
This would be in addition to funding for the Crossrail 2 line in London and the Northern Powerhouse Rail, which will improve links between Sheffield, Hull, Liverpool and Newcastle, he said.
Sir John insisted the call for an extra £43bn of infrastructure spending was not an "unaffordable pipe dream", but rather the best way to "make the most of all that HS2 will have to offer".
However, his suggestion is likely to infuriate opponents of HS2.
Tory MP Cheryl Gillan, a longstanding critic of the project, said: “One of the major problems has always been that the connectivity is not there.
“But I don’t think anybody expected it to be twice the cost of HS2. This is money that wouldn’t be going into schools, the health service and making the existing railway system efficient and effective.
“It’s time for the government to re-evaluate from top to bottom whether this project is value for money for the taxpayer.”
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