The Tay Bridge (sometimes unofficially the Tay Rail Bridge) is a railway bridge approximately 2.25 miles long that spans the Firth of Tay in Scotland, between the city of Dundee and the suburb of Wormit in Fife.
The original Tay Bridge was designed by Thomas Bouch, who received a knighthood following the bridge's completion. It was a lattice-grid design, combining cast and wrought iron.
Proposals for constructing a bridge across the River Tay date back to at least 1854. The North British Railway (Tay Bridge) Act received the Royal Assent on 15 July 1870 and the foundation stone was laid on 22 July 1871. As the bridge extended out into the river, it shortly became clear that the original survey of the estuary had not been competent. The bedrock, at a shallow depth near the banks, was found to descend deeper and deeper, until it was too deep to act as a foundation for the bridge piers. Bouch had to redesign the piers, and to set them very deep in the estuary bed to compensate for having no support underneath. He also reduced the number of piers by making the spans of the superstructure girders longer than he had originally planned.
It was 3465 yards long, was carried on eighty-five piers, with spans varying in width from 29ft to 245ft, and accommodated a single line of rails.[1]
The first engine crossed the bridge on 22 September 1877, and upon its completion in early 1878 the Tay Bridge was the longest in the world. The bridge was opened on 1st June 1878.
On the night of 28 December 1879 at 7.15pm, the first bridge collapsed after its central spans gave way during high winter gales. A train with six carriages carrying seventy-five passengers and crew, crossing at the time of the collapse, plunged into the icy waters of the Tay. All seventy-five were lost, including Sir Thomas's son-in-law. The disaster stunned the whole country and sent shock waves through the Victorian engineering community. The ensuing enquiry revealed that the bridge did not allow for high winds. At the time a gale estimated at force ten or eleven had been blowing down the Tay estuary at right angles to the bridge. The engine itself was salvaged from the river and restored to the railways for service.
1881 A Select Committee inquired, during 1880, into the question of replacing the structure that failed in December, 1879, and reported that the bridge should, in the interests of the public and the railway company, be reconstructed, but that it should be 77ft. instead of 8ft. above high water. It was also recommended that the North British Railway should obtain approval of its plans by two or three independent engineers of unquestionable standing and experience. The plans of the present bridge were, therefore, prepared by William Henry Barlow, and William Arrol and Co were the contractors.[2]
A new double-track bridge was designed by William Henry Barlow and built by William Arrol and Co 59 ft upstream of, and parallel to, the original bridge. The bridge proposal was formally incorporated in July 1881 and the foundation stone laid on 6 July 1883. Construction involved 25,000 metric tons (28,000 short tons) of iron and steel, 70,000 metric tons (77,000 short tons) of concrete, ten million bricks (weighing 37,500 metric tons (41,300 short tons)) and three million rivets. Fourteen men lost their lives during its construction, most by drowning.
The stumps of the original bridge piers are still visible above the surface of the Tay even at high tide.
The second bridge opened on 20th June 1887 and remains in use. The new Tay Bridge has a structure of 10,527ft long, carries a double line of railways, and its straight portion of 7397ft. lies parallel to the straight portion of the earlier bridge but 60ft away from it.[3]
See Also
Sources of Information
- [1] Wikipedia