1946 House Bill 1555. Resolve Providing For The Construction By The Transit Department Of Boston And The State Department Of Public Utilities Of Two Double Deck Viaducts Within The Boston Area To Carry Railroad, Rapid Transit And Highway Traffic Lanes, The Lower Deck Of Which Shall Carry Railroad And Rapid Transit Lines And The Upper Deck Shall Carry A Six-Lane Highway, And Of A Rapid Transit Line North Of East Boston To Salem And Beyond.