T AKING A CAB from Euston station in central London used to be a grim experience. In the 1960s the taxi rank was put in a poorly ventilated underground garage known as “the gas chamber”. In January cabbies were cheered when the rank was moved above ground to make way for HS 2, a planned high-speed railway between London and the north of England. Yet fears are growing that Boris Johnson’s government could derail the project.

HS 2 is not a done deal. Some £4bn ($5bn) of work has been completed, including exhuming 45,000 bodies from a graveyard at Euston to make way for new platforms. The rest of the cash was to be released this autumn if the project was on track to stay within its £56bn budget. But that looks unlikely. In December HS 2’s chairman resigned over rising costs. Last month his replacement warned that the bill could overrun by £30bn.

Boris Johnson is sceptical. The new prime minister has previously described HS 2’s costs as “spiralling out of control”. He has ordered a review by Douglas Oakervee, another former HS 2 chairman, who will report within six weeks on whether the project should be slimmed down or even scrapped. At the same time he has promised to build new railways between northern cities, dubbed HS 3, at a cost of £39bn.

Opponents of HS 2 — from the nerdish Campaign for Better Transport to the right-wing TaxPayers’ Alliance—worry that its huge budget will mean less money for improving local links. They say the cash should be spent on re-opening smaller lines closed in the 1960s, which would have greater economic benefit per pound spent, according to the government’s own analysis.