As part of the transition from Steam locomotives to diesel locomotives, Barrow Hill closed down its coaling stage and invested in two storage tanks and a distribution system for the new fuel.
Barrow Hill is now in a position to act as a fuelling point for main line locomotives. The new fuelling point is located away from the Roundhouse site on the access rails to the main line.
The new tank is interesting in its one-piece construction in that there are two tanks, one inside the other. The diesel is held in the inner tank and any leakage can be contained within the outer tank which forms the present day solution to the old bund wall.
The two large tanks at the end of our platform were for the storage of diesel fuel. The diesel would have been delivered by rail in tanker wagons and the fuel pumped into the two tanks. The tanks stand in a walled pit in the ground called a bund. This was designed to catch and retain any leakage from the tanks thereby preventing poluton from reaching the water table and the land drains. It is an interesting note that this original bund was not big enough to cope with the full spillage from a tank and would not be approved by today's tighter standards for polution containment.
The small building that is now our ticket office was originally the pump house to distribute the fuel to the five fuelling points in the roundhouse itself. To get the fuel safely to the fuelling pipes, trenches were dug in the Roundhouse floor, covered by a metal grate to enable maintanence access to the pipes. These trenches have now been concreted over. If we look carefully we can still see evidence of the metal lining of the trenches. The position of the actual fuelling points can still be seen by the rectangular sections alongside the trench.
The fuel used to power Diesel locomotives is termed red diesel, the same as that used by farmers. This has a dye put in to identify it as it is designated for use 'off-road' and carries a much lower rate of tax than standard 'white' diesel. At the time of writing the tax rate for red diesel was at 11.14p/litre, white diesel at 57.95p/litre.
Trenches in the roundhouse floor to carry the diesel supply pipes
Diesel locomotives obviously vary in size but the bigger locomotives used to pull freight and passenger services run at about a gallon per mile for each power unit used. Sounds a lot but when the size of the engine and the wagons or coaches are added they are remarkably efficient. One loaded freight train can move the same load as 60+ road vehicles, each consuming a more expensive fuel at a rate of 6/7miles per gallon each. Added to that the railway tends to be more direct and of course does not have junctions and traffic jams to add to the fuel use and pollution. The most expensive diesel locomotive to run was thought to be the Deltic class at around 0.7 miles per gallon.
How can the locomotives be so efficient? Apart from modern fuel economy measures which take every ounce of power from the fuel, the biggest use of fuel is to accelerate the train to a running speed. Once that speed is achieved it takes comparitively little effort to maintain it, momentum takes over and, unlike the power needed to constantly deform a set of road tyres, metal wheels on a metal track have very little rolling resistance. A few men can push a locomotive easily once the initial inertia is overcome. It takes just as much effort to stop it however!
Location of three of the original fuelling points