The Inland Water Transport and Docks sections were always part of the Royal Engineers. Formed in December of 1914 to deal with and to develop transport on canals and waterways of France and Belgium. They ran barges both in theatre and the UK and all the associated dock processes. The Section at first operated under the Director of Railways, but owing to the rapid development of Inland Water Transport, a special directorate was formed in October of 1915. They were responsible too for construction and repair of barges used in cross-channel transport, from 1916 centered at the secret Richborough Port. By 1918 242 barges were employed , including ten of 1,000 ton capacity. They were also responsible for the technical operation of Hospital Barges*. In February 1918 a cross-channel ferry service, was brought into operation between Richborough and Calais with a supplementary service from Southampton to Dieppe. These ferries were invaluable for the transport of locomotives, rolling stock, heavy guns and tanks. By 1918, it had become a large and well equipped seaport of 2,000 acres, complete with all services and capable of handling 30,000 tons of traffic per week. Building yards and workshops were constructed to increase the supply of barges and other small vessels needed in all theatres of war . The River Stour was diverted by cutting a new channel to render possible 2,300 ft of new wharf for the cross-channel barge service, in which at the end of the war, 242 barges were employed, including ten of 1,000 ton capacity. These Ro-Ro ferries were invaluable for the transport of locomotives, rolling stock, heavy guns and tanks. In all some sixty miles of broad gauge railway were laid at Richborough.
* The hospital barges were not specifically built or designed for troop evacuation or as a hospital until a few years into the Great War. Initially, they were converted from locally purchased Peniche. Conversion into 30 bedded hospital wards and QAIMNS nurses accommodation, and repairs were carried out at the IWT yard at Arques. The barges were usually located near Casualty Clearing Stations and Field Hospitals, They travelled in strings of three, pushed or pulled by tug, The crew appears to have been 2 bargemen, a cook (who also operated the stretcher lift), two trained nurses and various orderlies. The barges were usually in strings of three, pulled or pushed by tug under the command of a RE Inland Waterways Sergeant, and travelled to a port where the wounded were transfered to a ship or onward to a specialist hospital.
An idea of how the IWT system worked can be found at the National Archives in WO158/851. Unfortunately not yet digitised, so to view would require a trip to Kew.
The Transport Workers Battalions supplemented civilian labour wherever there was a proved shortage in the ports, railway centres, canals, and iron and steel works in the discharge of cargoes. They were solely used to supplement proved deficiencies in civilian labour. The first formed in May 1916, and by early in 1917 the number of the battalions was increased to a strength of 5,000 men and ultimately to an effective strength of 35,000.