This describes one of the greatest engineering disasters of the 19th century the collapse of the great iron bridge across the Firth of Tay at Dundee, Scotland.
During the mid-19th century after one engineering triumph after another the great engineers of the world felt they were invincible then came the bridge across the Firth of Tay in Scotland that smashed their coat of invincible armor. The feeling they had of being invincible came crashing to the ground with the collapse of the great railroad bridge at Dundee on a night when the wind was blowing at hurricane proportions on December 28, 1879. When the bridge collapsed it took a train load of passengers to a watery grave in the depths of the Firth of Tay.
At the time of its construction it was longest railway bridge in the world at the time of its construction in 1878. The Tay Bridge was 2 1/2 miles in length crossing the width of the Firth of Tay between Dundee and Wormit on the northern side of the firth in Scotland. Like many of the heroic structures that were built in the 19th century it was constructed from cast and wrought iron parts with an iron works being erected on the site of construction that supplied most of the parts required for the bridge. The bridge construction itself was under the direction of the famous bridge engineer Thomas Bouch who was knighted by Queen Victoria upon its completion.
The method of construction he chose to use for the construction of the bridge was what they called lattice grid construction. At the time this was a well known method of building bridges that had been used several times in both Great Britain and Europe.
At both ends of the bridge its footings were constructed on solid ledge that was buried under a thin layer of topsoil, but as the bridge got further out into the Tay this layer of soil became thicker until the bridge footings were no longer able to reach the bedrock underlying the Firth of Tay. This caused Bouch to continue building footings that were no longer anchored in bedrock. In order to compensate for this problem Bouch’s solution was to increase the distance between the spans of the bridge.
With the bridge completed the first train crossed upon September 20, 1877. The official opening waited until July 1, 1878 altogether the bridge lasted for a little more than a year and a half.
While Ulysses S. Grant was visiting the city of Dundee he commented, "It was a big bridge for a small city!"
A violent winter storm was raging when the last train rolled onto the bridge at 7:15 pm, and as its taillights vanished into the night the bridge collapsed shortly after taking the train with it along with the train load of passengers, and plunged them into the depths of the Firth of Tay. The train vanished in a stormy night taking with it its crew and passengers numbering 75 souls. Among the many who were lost in this disaster was Sir Thomas Bouch’s son-in-law.
The collapse of the bridge at Dundee brought a state of shock to the entire nation of Great Britain. The collapse also sent shockwaves through the entire community of the big Victorian engineers, and even to the walls of the House of Commons.
The subsequent investigation revealed that the bridge and undergone stresses by winds blowing from force 10 to 11 during the winter storm. These winds were blowing at right angles to the bridge subjecting it to the maximum amount of force that could be exerted. This kind of wind was not taken into consideration when the bridge was designed, and Thomas Bouch didn't even take into consideration the effects of wind as someone had told him that you didn't need to calculate the effects of wind speed for spans of less than 200 feet.
After the wreck the engine was recovered from the bottom of the Tay and restored to service afterwards it was known as the “Plunger.” The rest of the train and bodies were recovered in the spring of 1880.
At the inquiry the investigators discovered that there were several reasons why this bridge collapsed including poor design, and shoddy materials. One of the major problems with the iron castings was blow holes that formed in them the iron workers patched these holes with a product they called “egg” that left an invisible patch in the iron but did nothing for its strength.
It was also disclosed during the investigation that neither Bouch, nor the contractor were regular visitors at the building site while workers were recycling iron supposedly. It was presently discovered that many of the girders used in the construction of this bridge had wall thickness as a various thicknesses. Many of these cast iron parts that were defective were supposed to be recycled, they were instead patched using egg and used in the construction of the bridge.
Another problem was discovered in the logs that were supposed to hold the various parts of the bridge together when tested later the slugs were only able to sustain 20 short tons of pressure before they snapped. This was totally inadequate because they actually showed and unable to withstand 60 short tons of pressure before snapping. There was even the evidence that many of the inadequate castings were hidden from inspection before being used.
There are plenty of clues that were overlooked during the construction of the bridge indicating it was in trouble long before it was ever finished. Even after it was finished and maintenance inspector Henry Noble had heard the bridge rattling but instead of reporting the problem he shoved iron shims into the bridge to alleviate the problem. This is a problem that never stopped until the bridge collapsed.
The collapse of the bridge caused the downfall of Bouch’s reputation as a reputable engineer. Because the chairman of the investigating committee laid the blame for the bridge collapse on Sir Thomas Bouch. Being blamed for the bridge collapse was too much for Bouch and he died within the year.
The aftermath of the collapse of the Tay Bridge found Bouch and several other writers claiming that it was the last cars of the train that were blown off the bridge that caused the disaster. This was discredited by the investigative commission leaving the question unanswered of how this managed to destroy a whole half mile of bridging. The rules and regulations concerning bridge construction were tightened so the next big bridge that was built, the Firth of Forth Bridge didn't suffer the fate of the Tay Bridge.