There is a requirement for the supply of red diesel to high output sites, Aggregate Handling Depots (AHDs) and Material Handling Depots (MHDs). There will also be a requirement for the provision of Ad-Blue on an ad-hoc basis to the AHDs and MHDs. There may also be a future requirement as part of the contract to provide red diesel to other Network Rail owned fleets. Red diesel will need to be provided by the supplier directly to the rail mounted vehicles and to bunded tanks on site. Red diesel will be ordered by the site as and when it is required. There will be a requirement for between 4 400 000 to 8 300 000 litres of red diesel across the country.