More than £76 million will be spent on strengthening the Bidston Moss Viaduct, which has been jointly developed by Wirral Council, Merseytravel and the Highways Agency.
Bilfinger Berger, Costain, Interserve and Morgan Est all bidding for the work.
Once a contractor has been appointed and a firm price agreed, the Highways Agency will apply to the Department for Transport for full approval of the scheme.
Design work will start at the beginning of 2009 and the strengthening work is expected to begin in summer 2010, with completion by summer 2012.
Ms Winterton has also announced £15.6 million for the Thornton to Switch Island link, which is expected to be completed in 2012.