The excursion sets out Armagh Methodist Sunday School had organised a
day trip to the seaside resort of
Warrenpoint,
County Down, a distance of about . A special
Great Northern Railway of Ireland (GNR(I)) train was arranged for the journey, intended to carry about eight hundred passengers. The railway route was steeply
graded and curved, and the first from
Armagh railway station involved a steep continuous climb, up a gradient of 1 in 82 (1.22%) and then 1 in 75 (1.33%). Elsewhere on the line, there were gradients as severe as 1 in 70.2 (1.42%). Asked to provide
rolling stock for a special train to take 800 excursionists, the locomotive department at
Dundalk sent fifteen vehicles hauled by a 'four-coupled' (
2-4-0) locomotive; however, the instructions to the
engine driver, Thomas McGrath, were that the train was to be of thirteen vehicles. There were more intending passengers than anticipated and, to accommodate the excursion, the Armagh
station master decided to use all fifteen vehicles. McGrath, who had never driven the route before (but had been over it with excursion trains when a
fireman), objected to these instructions, saying that his instructions were that the train was to be of thirteen vehicles at most. According to the driver: Two other witnesses said that McGrath had asked for a second engine if more
carriages were added and had been refused by the station master, as none was available; McGrath (in supplementary evidence given "through the railway company's officers") denied this. The station master's evidence was that the discussion was about adding further carriages to the fifteen with which the locomotive had arrived. The general manager's chief clerk was to accompany the excursion; he suggested that the engine of the routine train that would be following twenty minutes behind could assist the excursion up the bank, or that some carriages could be left to come on with the routine train. Following his conversation with the station master, however, McGrath refused the assistance. The train therefore set off with fifteen carriages, containing about 940 passengers. The carriages were full, and some passengers travelled with the
guards. Tickets were checked before setting off and to prevent people without tickets joining the excursion; once each compartment had been checked its doors were locked. Initially the train made progress up the steep gradient at about but stalled about before the top of the gradient.
Dividing the excursion train To prevent the train rolling back, the brakes were applied. The train did have continuous
brakes, (
i.e., all carriages had brakes which could be operated by the driver), but they were of the non-automatic vacuum type. They were applied by creation of vacuum in the brake pipes and released by admitting air to the pipe. This was the opposite of the arrangement preferred by the Board of Trade ('automatic continuous brakes') in which brakes were held off by vacuum (or compressed air) generated by the engine, so that on loss of vacuum (e.g. from a leaky connection or a connection parting) the brakes came on automatically. The two
brake vans, however, (one immediately behind the engine tender, the other at the rear of the train) also had hand-operated brakes, each under the control of a guard. These were applied. The chief clerk directed the train crew to divide the train and proceed with the front portion to
Hamilton's Bawn station, about away, and leave that portion there, and return for the second portion. Owing to limited siding capacity at Hamilton's Bawn, only the front five vehicles could be taken on there; so the rearmost ten vehicles would have to be left standing on the running line. Once this rear portion was uncoupled from the front portion, the continuous brakes on it would be released, and the only brakes holding it against the gradient would be the hand-operated brakes in the rear brake van. For a goods (freight) train in a similar situation, the wheels would have been 'scotched' against roll-back, and guard's vans on goods trains carried 'sprags' with which to do this. Those on passenger trains with continuous brakes were not required to carry sprags, and the excursion train did not. The guard in the rear van having applied his handbrake then (on the instructions of the chief clerk) dismounted and scotched the wheels of his van with pieces of ballast. He then also scotched the near rearmost vehicle on its righthand wheels and intended to similarly scotch its lefthand wheels before going back down the track with flags and
detonators to protect the train from the scheduled service which was to set off from Armagh 20 minutes after the excursion. The train was
screw-coupled; each carriage was first coupled by a loose chain and hook coupling to the next; the slack on this was then taken up by a turnbuckle screw arrangement, until the buffers of the two carriages were touching. To uncouple, there needed to be some slack in the coupling; as the train had stopped all the couplings were under tension. Once the vacuum brake connection to the rear portion was broken, any attempt to introduce slack into the coupling between the two portions would be defeated by the rear portion settling back to rest its weight upon the rear van brakes. To assist uncoupling the front van guard therefore scotched one of the wheels of the sixth vehicle, that is, the front vehicle of the rear portion being detached. Loosening the turnbuckle thus transferred the weight of the rear portion to the scotch on the sixth vehicle, rather than to the rear van brakes. The couplings to the rear of the sixth vehicle remained under tension, and the slack introduced remained in the coupling between the fifth and sixth vehicles, which could be unhooked.
The rear carriages run away The uncoupling accomplished by the front van guard, the driver attempted to start the front portion away. It rolled back slightly, jolting the rear portion; which caused the wheels of the front vehicle of the rear portion to ride up over the stones underneath them. The rear portion had been standing with its couplings tight, but now only the rear two vehicles were in any way restrained, so that the leading eight vehicles of the rear portion fell back on to them. The momentum of the eight vehicles closing on the rear two was sufficient to push them over the stones, crushing them in turn, so that now only the handbrake on the rear brake van was effective. It was overcome by the weight of ten vehicles, and the rear portion began to move downhill and gathered speed down the steep gradient back towards Armagh Station. The train crew reversed the front portion and tried to catch the rear portion and re-couple it, but this proved to be impossible.
Collision plan of accident site The line was operated on the time interval system The engine of the scheduled train overturned, and the connection to its tender was lost. This train was also fitted with 'simple' (non-automatic) continuous vacuum brakes, and these were lost when the engine became disconnected. The train split into two sections, both running back down the gradient towards Armagh. Application of the handbrakes on the tender and on the brake van brought the front and rear halves of the scheduled train to a stop without further incident, a witness telling the inspector "The tender was slightly damaged, but none of the vehicles, and I heard from the guard that a horse in the box next the tender was not injured". The occupants of the rear of the excursion train were not so lucky. The two rearmost vehicles of the excursion train were utterly destroyed, and the third rearmost very badly damaged. The debris tumbled down a embankment. ==Causes of the runaway==