Brakesman J.F. Lewis was standing near his van in the space between the main line and the latter siding at the moment of the collision, and was overwhelmed by the wreckage of the coal wagons and fatally injured. He died soon after being picked up out of the debris.

The line through Tredegar Station and thence to Nantybwch is single, and is worked on the electric staff  system. South of Tredegar Station and north of Nantybwch the line is double.

The gradients are severe, viz: through Tredegar Station 1 in 150; thence to Sirhowy 1 in 54, with a short length of 1 in 90 immediately south of Sirhowy; from Sirhowy to Nantybwch 1 in 42, with a short length of 1 in 33 south of Nantybwch, all rising towards the north, i.e. towards Nantybwch. The curves are generally easy, but near Nantybwch there is an S curve, the lower part of which has a radius of 15 chains, and the upper part a radius of 10 chains , with about 100 yards of straight between them.

There is a rule in force at Sirhowy signal box to the effect that: “After the passage of an Up mineral train which is not assisted by a bank engine in the rear, the signalman at this station must turn the points at the north end of the station to the siding until ‘train out of section’ is received for such train from Nantybwch, unless it is necessary to turn the points to allow a train to leave for Tredegar from

the south end of the station; but as soon as this train has left, the signalman must turn the points at the north end of the station for the siding if ‘train out of section’  has not been received from Nantybwch.”

The engine (No.269) which was taking the mineral train to Nantybwch was a 8-wheeled 6-coupled side tank engine. The coupled wheels were 4ft 3in diameter. Its weight was 43 tons, of which 33 tons 11 cwt. were carried on the coupled wheels. The engine was fitted with automatic vacuum brake  and hand brake , working blocks on all the coupled wheels, the blocks being simultaneously applied by means of ‘pull-bars’ on both sides of the engine.

The maximum load for such an engine between Tredegar and Nantybwch is fixed at nine loaded wagons and a brake van. In this case the train consisted of nine wagons loaded with coal and coke and a ten-ton brake-van, the total weight being 243 tons 11 cwt, carried on 40 wheels.

The distance from Tredegar to Sirhowy is slightly under a mile, and from Sirhowy to Nantybwch is about a mile. The train was stopped on the incline at the northern end of the 15-chain curve ½ mile short of Nantybwch, and the wagons ran back 1½ miles before reaching the point of collision.