 The revised route would comprise in tunnel or green tunnel compared to , a 55% increase.Overall, of the route will be in tunnel or cutting, while will be on viaduct or embankment, a reduction of from the route in the original consultation documents.In April 2013 a decision by HS2 Ltd and the Department for Transport to recommend further bore tunnelling under the 'Northolt Corridor' in the London Borough of Ealing was announced in an HS2 Ltd press release.