Railway accident on the Dee Bridge

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The railway accident on the Dee Bridge was a serious railway accident that occurred on May 24, 1847 near Chester , Cheshire , on the North Wales Coast Line by a bridge collapse and killed at least five people.

Accident site
Accident site
The scene of the accident today. The photo was taken during high tide.

Realities

Infrastructure

The double-track bridge was on the Chester and Holyhead Railway , which was built by Robert Stephenson and completed in September 1846. This also included a bridge over the Dee with three spans, each more than 30 meters long. Each span consisted of four cast iron girders reinforced with wrought iron , with the cast and wrought iron components riveted together . These rested on brick bridge piers. Two girders each carried one of the two tracks . Wooden beams on which the rails were mounted were placed on the girders . As a material property of cast iron it was known that it can withstand pressure very well, but that it reacts very brittle to tensile loads and bending and can break.

A few hours before the accident , gravel had been poured over the wooden sleepers on which the rails were mounted to prevent the sleepers from catching fire from glowing coal or slag lost by steam locomotives . Robert Stephenson had taken this precaution because shortly before a railway bridge constructed by Isambard Kingdom Brunel for the Great Western Railway in Uxbridge , London , caught fire and burned down in this way.

The bridge at Chester had been inspected together with the line before commissioning by the railway inspectorate ( Her Majesty's Railway Inspectorate ).

vehicles

The train consisted of a locomotive with a tender , a baggage car and three passenger coaches , one of the first and two of the second class . Only "two dozen " travelers are said to have been on board.

the accident

Although the bridge was new and without any complaints, the accident occurred: the local train from Chester to Ruabon was on the last bridge girder (as seen from Chester) when the outer of the two cast iron girders of the roadway substructure broke. The engine driver, who had felt an unusual vibration , gave all the available steam to the cylinders to get the train off the bridge. The locomotive still managed that, but the clutch for a Tender already ripped. The tender and the following wagons fell into the Dee, which was about ten meters below.

consequences

Immediate consequences

Five people died: the stoker (he was on the tender), the train driver and two conductors - all three were in the baggage car behind the tender - and a traveler . Nine travelers were also seriously injured.

Rescue operation

The engine driver showed the greatest presence of mind and great courage: he drove the locomotive to the next operating point , Saltney Junction , triggered the alarm there, switched to the track in the opposite direction and drove past the scene of the accident, over the damaged bridge, to also trigger the alarm in Chester and to prevent another train from making the route to the damaged bridge.

examination

The investigation by the railway supervisory authority revealed that the cast iron had become brittle due to the changing load - when a train drove over the bridge - and the relief - when it left the bridge again - and had therefore broken. Tests showed that the girders bent by several centimeters with each pass. The reinforcement by the wrought iron elements could not compensate for this, as these were only anchored in cast iron elements. The construction as a whole was therefore rated as faulty. The weight of the recently applied ballast certainly contributed to the accident. The investigation of the incident by the coroner accused the designer of negligence on the basis of this report from the railway supervisory authority .

Robert Stephenson, however, claimed that the locomotive must have derailed and the impact it caused against the bridge caused it to break. But this was unbelievable, since the locomotive did not crash with it, rather the engine driver immediately drove to the next station and informed the staff there about the accident. Scottish engineer William Fairbairn , after investigating several incidents in the construction sector with the use of cast iron, is said to have warned Stephenson at a meeting of the Institution of Civil Engineers in London a few months before the construction of the bridge because of the mechanical behavior of cast iron girders, to use them when building bridges. Robert Stephenson's reputation as an engineer was severely damaged by the accident.

The report of a royal commission of inquiry into the causes of the accident then spoke out in 1849 against the use of cast iron in load-bearing structural elements in the construction of railway bridges.

Consequences

Nevertheless, there were a number of other accidents in the following years, in which the use of cast iron in load-bearing elements was (partly) responsible, the most famous of which was the collapse of the Firth-of-Tay Bridge in 1878. Only after the railway accident at Norwood Junction in 1891 and a review of all bridges of the corresponding design by John Fowler , he spoke out in favor of replacing all relevant structures.

The bridge over the Dee near Chester was rebuilt in wrought iron after the accident.

See also

literature

Web links

Individual evidence

  1. ^ Rolt: Red for Danger , p. 94.
  2. ↑ In contrast, the London Illustrated News , which appeared a few days later, reports of ten dead (NN: Frightful Accident ) and Rolt: Red for Danger , p. 94, of 16 injured.
  3. ^ Rolt: Red for Danger , p. 94.
  4. ^ Rolt: Red for Danger , p. 94.

Coordinates: 53 ° 11 ′ 10.8 "  N , 2 ° 54 ′ 17.9"  W.