Tay Bridge

In 2003, the bridge was strengthened and refurbished, winning a British Construction Industry Engineering Award to mark the scale and difficulty of the project.

The original design was for lattice girders supported by brick piers resting on the bedrock, shown by trial borings to lie at no great depth under the river.

[citation needed] The engineering details on the Tay Bridge were considerably simpler, lighter, and cheaper than on the earlier viaducts.

This 'spigot and faucet' configuration was used, apparently without machining, on some Tay Bridge pier columns, but on some the bolts were relied upon to ensure correct alignment.

Two cotters, metal wedges, were then positioned to fill the rest of the slot overlap, and driven in hard to put the tie under tension.

[12] The various bolt heads were too close to each other, and to the column for easy tightening up with spanners; this coupled with lack of precision in the preparation of the channel iron braces led to various on site fitting expedients (one of them described by a witness to the enquiry as "about as slovenly a piece of work as ever I saw in my life".

No cement of any kind was used in the whole structure, and the piers when completed, and the vertical and horizontal wrought-iron bracings keyed up, are nearly as rigid as though they were one solid piece.......

Thus, when the pieces of the viaduct had to be put together at the place of erection there was literally not a tool required, and neither chipping or filing to retard the progress of the work.

[19] Whilst Bouch was in the process of revising his design, the company which had been awarded the contract for the bridge's construction, Messrs De Bergue of Cardiff, went out of business.

[citation needed] The change in design increased cost and necessitated delay, intensified after two of the high girders fell when being lifted into place during the night of Friday, 3 February 1877.

Like all UK rail lines, the Tay Bridge was subject to a Board of Trade inspection before it could carry passenger trains.

The inspection was conducted 25–27 February 1878[25] by Major General Hutchinson of the Railway Inspectorate, who measured the deflection of the 245 ft (75 m) bridge girders under a distributed load of 1.5 tons per foot (5 t/m) due to heavy locomotives, travelling at up to 40 mph (64 km/h), as less than 2 inches (51 mm).

The lateral oscillation [roughly, rhythmic side-to-side movement], as observed by the theodolite when the engines ran over at speed, was slight and the structure overall showed great stiffness".

[26] Hutchinson did require some minor remedial work to be performed, and also issued a "recommendation" to impose a 25 mph (40 km/h) speed limit on traffic passing over the bridge.

The inspection report added: "When again visiting the spot I should wish, if possible, to have an opportunity of observing the effects of high wind when a train of carriages is running over the bridge".

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.

[citation needed] The collapse of the bridge, despite opening only nineteen months earlier after being found safe by the Board of Trade, had a long-term effect on wider society.

In 2005, Scottish playwright Mike Gibb and composer Mairi Paton premiered their musical titled Five Pound and Twa Bairns in Dundee.

[citation needed] Almost immediately following the Tay Bridge failure, the North British Railway company began to develop plans for its reconstruction or replacement.

[32] In response to this inquiry, Mr Walker, the general manager of the North British Railway, stated his opinion that there was no more suitable site than what had been chosen, emphasising the relatively large interchange of traffic in the area and the importance of making the line as direct as practically possible.

Additionally, a number of local witnesses, who included several leading merchants from Dundee, spoke favourably of the proposed location.

[32] The North British Railway, placing great importance on the connection between Fife and Forfarshire, was committed to developing a viable design.

Following experiments upon the first bridge's remains, Barlow gave his opinion that the intact portions should be abandoned in favour of a new structure spanning between the two shores.

For the new bridge's design, Messrs Barlow elected to refrain from using any untested engineering principles, instead choosing to strictly adhere to established methodology.

These spans are ordinary brick arches, backed by cement concrete and set on top of piers which are supported by pairs of columns.

The decking is composed of steel and is surrounded both sides of the bridge by a closely knit latticework, which functions as a wind screen as well as somewhat protecting the workers.

When the construction work is broken down, the founding of the piers was calculated as having cost £282,000, the installation of the girders and parapets £268,000, while £90,000 was involved in producing the approaches and arches.

[32] Some additional costs of roughly £16,000 had been incurred to improve the approach to the bridge from Newport; the branch line was reconstructed for a distance of half a mile eastward.

[35] During 2003, a £20.85 million strengthening and refurbishment project on the bridge won the British Construction Industry Civil Engineering Award, in consideration of the staggering scale and logistics involved.

At the same time, hundreds of thousands of rivets were removed and replaced, all of which was being done by workers who were in exposed conditions while high over a firth with fast-running tides.

At dusk. One of the stumps of the original bridge is silhouetted against the sunlit Firth.
The second (current) Tay Rail Bridge from Wormit on the south bank
The current Tay Rail Bridge as seen across the Tay Estuary from Newport-on-Tay
The original Tay Bridge before the 1879 collapse
Tay bridge following the collapse
Fallen girders near the Tay Bridge
Tay Bridge and Signal Box Wormit
Video showing view from northbound passenger train crossing bridge towards Dundee. Camera pointing primarily eastwards. (Contains some flickering).
Video showing train approaching the Dundee end of the bridge.
A 1910 Railway Clearing House Junction Diagram showing the Tay Bridge and connecting lines, also the ferry connecting Tayport with Broughty Ferry