The tunnel replacement scheme for the Gateway rail project in New York could cost $10bn (6.6bn), according to preliminary figures.
The total cost of the Gateway project – a proposed programme of rail infrastructure improvements designed to improve current services and double capacity for passenger trains running under the Hudson River – is reported to be around $20bn (£13bn).
Speaking at a public meeting, Patrick Foye, executive director of the Port Authority of New York and New Jersey, emphasised that estimates for the project were “preliminary”.
Foye also urged federal authorities to accelerate the permitting process. He said reducing this process by one year could save £1bn (£661M).