Extra £174m earmarked for ‘spiralling’ bill for Lower Thames Crossing

More than 3bn is due to be spent on the proposed road tunnel between Kent and Essex, which is estimated to have higher costs per mile than HS2

Ministers have earmarked more than 170m extra to help build the Lower Thames Crossing road tunnel, fuelling concerns over the spiralling" costs of one of the UK's largest planned infrastructure projects.

The proposed 11bn route under the Thames between Kent and Essex is already estimated to cost more each mile than the HS2 high-speed rail link from London to Birmingham. It was given the funding boost as part of a plan to spend 3.1bn of public money on the project, before a hoped-for injection of 7.5bn by a private sector firm.