the transportation of newly constructed ships to coastal ports for final fitting out. Of the 1,051 LSTs built during the war, 670 were supplied by five "cornfield shipyards" in the Middle West. Dravo Corporation's facility at Neville Island, Pennsylvania, designated the lead shipyard for the project, built 145 vessels and developed fabrication techniques that reduced construction time and costs at all of the LST shipyards. The Missouri Valley Bridge & Iron Co. built the most LSTs of any shipyard, with 171 constructed at Evansville, Indiana. Chicago Bridge and Iron's shipyard in Seneca, Illinois, launched 156 ships and was specifically chosen because of their reputation and skills, particularly in welding. The American Bridge Company in Ambridge, Pennsylvania, built 119. Modifications By 1943, the construction time for an LST had been reduced to four months. By the end of the war, this had been cut to two months. Considerable effort was expended to hold the ship's design constant, but, by mid-1943, operating experience led to the incorporation of certain changes in the new ships. From LST-513, the elevator to transfer equipment between the tank deck and the main deck was replaced with a ramp that was hinged at the main deck. This allowed vehicles to be driven directly from the main deck down to the tank deck and then across the bow ramp to the beach or causeway, speeding the process of disembarkation. Changes in the later LST-542 class included the addition of a navigation bridge; the installation of a water distillation plant with a capacity of per day; the removal of the tank deck ventilator tubes from the center section of the main deck; the strengthening of the main deck in order to carry a smaller Landing Craft Tank (LCT); and an upgrade in armor and armament, with the addition of a 3"/50 caliber gun. LST Mk.3 Design The LST (2) design was successful and production extensive, but there was still a need for more LSTs for British operations. As such, it was decided to build a further 80 of the ships in the UK and Canada to be available in the spring of 1945. The British Staff drew up their own specification, requiring that the ship: Be able to embark and disembark tanks, motor transport, etc., on beaches of varying slopes; and amphibians and DD Sherman tanks into deep water Carry five Landing Craft Assault (LCA), or similar craft, and