A section of the £33.1bn High Speed Two railway line in London is likely to be tunnelled, leading to an estimated 15 month reduction to the construction timetable.
HS2 Ltd will recommend that the line be tunnelled between North Acton and Northolt in order to reduce disruption to residents and traffic in north west London.
The transport secretary is “minded to take the option forward”, according to a statement from HS2.
HS2 said a report it commissioned had recommended the tunnel as the best option because a surface route would have disrupted traffic, cost as much or more than a tunnel and taken longer to build.
HS2 said the study was carried out after local residents, Ealing Council and the Mayor of London suggested that the section of line should be tunnelled.
The proposal would mean that the existing tunnel at West Ruislip would be extended by 9km to stretch to 14km, making it the longest tunnel on the route.
The original proposal involved adapting exiting rail lines in Ealing and Northolt and replacing both spans of the Hangar Lane Gyratory.
The tunnel option will require shafts but HS2 estimates it will be 15 months faster to build than the surface route.
HS2 Ltd community and stakeholder manager for London Peter Fry said: “The study we commissioned found that for this specific section of the line, the cost of tunnel would be comparable with a route on the surface without the need to replace bridges and divert associated utilities.
“The proposed tunnel will be included as the preferred option in the draft environmental statement for the first phase of HS2, so the community and stakeholders will have the opportunity to respond to this proposal as part of the consultation in coming months.”
Alex Nieora, chairman of North Ealing Against High Speed Rail, said campaigners had been telling HS2 Ltd for at least 18 months that a tunnel was the better option. He siad: “It’s great news. We are glad they listened to us but they should have done so from day one.”