Chaldron waggons had sloping sides and bottom opening doors that allowed their contents to be emptied rapidly into storage areas below. This method originated on the coal staithes of Tyneside where chaldrons had been running on wooden rails delivering coal since 1760 and by 1812 were being used on coastal coal drops. When the S&DR first opened, they commissioned 150 waggons to carry coal to their coal depots, but they were not bottom opening, so it took considerable time for staff to empty them. They quickly realised their mistake and George Stephenson was instructed to come up with a more efficient design based on the Tyneside chaldron. On the 7th October 1825 the S&DR Company commissioned six additional waggons with ‘Bottom Boards in Order that the Committee may be satisfied as to the most advisable plan being adopted for delivering Coals at the Depots.’ The waggons had been enlarged to hold 53 hundred weights by the addition of sideboards or ‘greedy boards’ which made the waggons taller. A downward opening door was hung on two thick iron bars and fitted with a cross bolt. When the bolt was withdrawn, the door fell open and the load poured out.
On October 21st, it was ‘Resolved that all the Waggons which are to be made after this day shall be made upon the plan of Bottom Boards’ and that ‘the unfinished Depots be made to suit the Waggons with bottom Boards.’ And so the chaldron waggon took its place in railway history.