Current weight limit of 3.5 tonnes to be lifted to allow heavier vehicles to use all lanes.
The Department for Transport and the Highways Agency are to invest more than £66 million into strengthening the Bidston Moss Viaduct.
This will allow heavier vehicles to be able to use all lanes, and the current weight limit restricting vehicles using the outside lane of the central structure to 3.5 tonnes will be lifted.
This will improve traffic flow for all users of the key strategic route between Wirral and Liverpool city centre, which carries around 63,000 vehicles a day, including approximately 5,000 HGVs.
The scheme has been jointly developed by Wirral Council and Merseytravel, who provided up to £3.6 million, and the Highways Agency.
Design and preparatory site work started at the beginning of 2009 and the strengthening work will be completed by spring 2012. The next step will be for the main works to start on site in May.
Transport Minister Paul Clark said: "This new investment underlines the Government's commitment to delivering major improvements in the North West."
Department for Transport