FEA-F Network Rail black RHTT (twin pack) - 642006 Sandite+Water+Tank & 642047 Sandite+Tank+Tank (Pack 1)

The 2005 railhead treatment train (RHTT) season marked a major step in Network Rail’s modernisation, introducing purpose-built FEA-F wagons and replacing an assortment of ageing second-hand vehicles. Fifty 60-ft flats, built in Poland by Greenbrier Europe, were numbered 642001–642050 and designed to carry modular equipment, allowing retirement of General Utility Vans and TTA water tanks. Earlier KFA wagons had already introduced large water tanks and high-pressure jetting systems, later supplemented by Sandite applicators capable of operating at up to 60mph.

Operational changes accompanied the new fleet. The dominance of English Welsh & Scottish Railway ended in 2004 as Direct Rail Services (DRS) and GB Railfreight took on contracts, while Class 37 locomotives gave way to Class 66 and 67 traction. DRS led operations in 2005, using a mix of locomotives across regional circuits.

Typical formations combined water-jetting and Sandite modules with multiple water tanks, sometimes adding extra wagons for long-distance routes. Subsequent developments included revised nozzle arrangements in 2007, wider operator involvement, and module upgrades such as larger fuel tanks in 2009. Additional wagons joined the fleet in 2013 following refurbishment. By 2025, operation of 29 trainsets was shared between Colas and GB Railfreight, employing a varied mix of modern and heritage locomotives.