A train ferry is a ship (ferry) designed to carry railway vehicles. Typically, one level of the ship is fitted with railway tracks, and the vessel has a door at the front and/or rear to give access to the wharves. In the United States, train ferries are sometimes referred to as "car ferries", as distinguished from "auto ferries" used to transport automobiles. The wharf (sometimes called a "slip") has a ramp, and a linkspan or "apron", balanced by weights, that connects the railway proper to the ship, allowing for tidal or seasonal changes in water level. While railway vehicles can be and are shipped on the decks or in the holds of ordinary ships, purpose-built train ferries can be quickly loaded and unloaded by roll-on/roll-off, especially as several vehicles can be loaded or unloaded at once. A train ferry that is a barge is called a car float or rail barge. History An early train ferry was established as early as 1833 by the Monkland and Kirkintilloch Railway. To extend the line over the Forth and Clyde Canal in Scotland, the company began operating a wagon ferry to transport the rolling stock over the canal. In April 1836, the first railroad car ferry in the U.S., Susquehanna, entered service on the Susquehanna River between Havre de Grace and Perryville, Maryland. The first modern train ferry was Leviathan, built in 1849. The Edinburgh, Leith and Newhaven Railway was formed in 1842 and the company wished to extend the East Coast Main Line further north to Dundee and Aberdeen. As bridge technology was not yet capable enough to provide adequate support for the crossing over the Firth of Forth, which was roughly across, a different solution had to be found, primarily for the transport of goods, where efficiency was key. The company hired the up-and-coming civil engineer Thomas Bouch who argued for a train ferry with an efficient roll-on roll-off mechanism to maximise the efficiency of the system. Custom-built ferries were to be built, with railway lines and matching harbour facilities at both ends to allow the rolling stock to easily drive on and off the boat. To compensate for the changing tides, adjustable ramps were positioned at the harbours and the gantry structure height was varied by moving it along the slipway. The wagons were loaded on and off with the use of stationary steam engines. Although others had had similar