Cornwall Railway viaducts
At the time of construction of the line, money was in short supply due to the collapse in confidence following the railway mania, and the company sought ways of reducing expenditure.
On the advice of the Victorian railway engineer Isambard Kingdom Brunel, they constructed the river crossings in the form of wooden viaducts, 42 in total, consisting of timber deck spans supported by fans of timber bracing built on masonry piers.
Workshops were established at Lostwithiel where timber could arrive on barges to be preserved and cut to size.
[1] The choice of timber was made to keep initial costs down, but Brunel had warned that this meant more expensive maintenance—running to £10,000 annually.
The lease precluded the conversion of the line to 4 ft 8+1⁄2 in (1,435 mm) standard gauge, and the Cornwall Railway refused to pay for the widening of the viaducts during rebuilding sufficient to accommodate a double line of standard gauge tracks.
Following the amalgamation of the two companies on 1 July 1889 all the remaining viaducts on the main line to Truro were replaced.
Most were either rebuilt in situ or by a replacement viaduct built immediately alongside, and in the latter case many of the original piers still remain today.
Peter John Margary, the Cornwall Railway engineer from 1868 to 1891,[6] classified them as classes A to E. Brunel's designs allowed any defective timber to be withdrawn and replaced.
The first decay usually occurred at the bottom of legs where they were seated in the cast iron chairs, and around bolt holes.
The other area with significant decay was generally underneath the decking that carried the track and ballast.
After World War I it became difficult to obtain the preferred yellow pine and other timber with shorter life was used instead, although by this time only the viaducts on the Falmouth branch remained in use.
Millbay station and its connecting lines (on which Stonehouse Pool Viaduct was located) were closed in 1964; the girders have since been removed and a steel work of art has been erected in its place.
On 6 May 1859 the engine of the 7.25 p.m. train from Plymouth was approaching St Germans when it left the rails, hit the parapet of the viaduct and fell into the mud below, landing upside down.
A second guard, Richard Paddon, was given a reward of five pounds for his part in keeping the remainder of the train on the viaduct and helping to rescue the survivors.
[24][25][26] At the inquest held on 10 May 1859, the Permanent Way Inspector, the Traffic Superintendent, and Mr Brereton, Brunel's Chief Engineer, were all unable to account for the derailment, and the jury verdict was accidental death.
It was not possible to remove individual timbers from the trestles, unlike the fan viaducts which were designed with piecemeal maintenance in mind.
The piers were raised in brick and new iron girders replaced the timber, the work being completed on 23 January 1898.
An accident occurred on 9 February 1897 during the reconstruction while a gang of 17 workmen were working below the viaduct superstructure on a platform that collapsed, throwing 12 of the men 140 feet (43 m) to their deaths.
They were working in the seventh span; cross-girders had been installed and they were positioning a longitudinal wrought iron rail-bearer, moving it by hand with one end supported on the viaduct pier.
The supervising engineer said a chain should have been used to support the centre, to take part of the load of the men and the rail-bearer.
The inquest statements throw an interesting light on the working methods of the day: Samuel Stephens, railway labourer, Liskeard, said he had been employed on Coldrenick-viaduct since the summer.
Just as the other end of the girder was approaching a cross-girder on which it was intended to rest it the staging suddenly collapsed and 12 of the gang fell into the valley beneath.P.
John Binding, in his study of Brunel's Cornish Viaducts, thought that Moorswater, by virtue of its size and location, was surely the most spectacular.
To the south can be seen Coombe Junction Halt while to the north is the remains of Moorswater yard, still used by freight trains.
The quarry to the south of the railway provided stone for both the building and later rebuilding many of the viaducts in Cornwall.
[43] Milepost 269.5, 1.25 miles (2.0 km) west of Doublebois above the Trago Mills out-of-town shopping complex.
This meant that the northern half of the new viaduct was built first, the timber structure dismantled, and then the southern side completed.
Probus and Ladock Halt was opened a quarter of a mile east of the viaduct site on 1 February 1908.
The soft nature of valley floor meant that some piers had to have a foundation built for them by sinking a temporary caisson and removing the mud within it.
[73] This viaduct crossed Restronguet Creek and the Redruth and Chasewater Railway near its Devoran terminus.
