The Carnon viaduct carries a

railway Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...

line from

Truro Truro (; kw, Truru) is a City status in the United Kingdom, cathedral city and civil parishes in England, civil parish in Cornwall, England. It is Cornwall's county town, sole city and centre for administration, leisure and retail trading. Its ...

to Falmouth – now branded the

Maritime Line The Maritime Line is a railway line that runs in the valley of the River Fal from Truro, the county town, to Falmouth on the south coast of Cornwall, England. History The railway line, now known as The Maritime Line, was built by the Cornwal ...

– over the valley of the

Carnon River The Carnon River ( kw, Avon Carnon) is a heavily polluted river in Cornwall, United Kingdom. It starts in Chacewater. Trewedna Water and River Kennall flow into the Carnon before it merges with Tallack's Creek to become Restronguet Creek, which ...

in west

Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

. The viaduct is situated half-a-mile (800 metres) northeast of Perranwell station which is five miles (8 km) from the line's terminus at Falmouth and three miles (5 km) from its junction with the

Cornish main line The Cornish Main Line ( kw, Penn-hyns-horn Kernow) is a railway line in Cornwall and Devon in the United Kingdom. It runs from Penzance to Plymouth, crossing from Cornwall into Devon over the famous Royal Albert Bridge at Saltash. It directly ...

at Truro. The present nine-arch

masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term ''masonry'' can also refer to the units themselves. The common materials of masonry construction are bricks, building ...

viaduct replaced an earlier 19th-century structure designed by

Isambard Kingdom Brunel Isambard Kingdom Brunel (; 9 April 1806 – 15 September 1859) was a British civil engineer who is considered "one of the most ingenious and prolific figures in engineering history," "one of the 19th-century engineering giants," and "one ...

for the

Cornwall Railway The Cornwall Railway was a broad gauge railway from Plymouth in Devon to Falmouth in Cornwall, England, built in the second half of the nineteenth century. It was constantly beset with shortage of capital for the construction, and was eventu ...

. The original viaduct was opened to traffic when the line was extended from Truro to Falmouth in 1863 and had a timber deck supported by timber trestles springing from eleven masonry piers. It was long and high. The present viaduct is of roughly the same dimensions as the original. It was built by A E Farr CIvil Engineers of Westbury for the

Great Western Railway The Great Western Railway (GWR) was a British railway company that linked London with the southwest, west and West Midlands of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament on 31 August 1835 and ran ...

as an entirely new structure immediately south of its predecessor and it cost £40,000. It has nine arches and opened to traffic in June 1933. The timberwork of the original structure was dismantled and removed but its masonry piers still stand beside the replacement viaduct. Construction of the original structure posed specific problems not encountered at the sites of other viaducts in Cornwall. The tidal limit of

Restronguet Creek Restronguet Creek is a tidal ria in south Cornwall, United Kingdom. It is a tributary of Carrick Roads, the estuary of the River Fal, and is situated approximately four miles (6.5 km) south of Truro and three miles (5 km) north o ...

extended further up the Carnon River valley than it does today and at the site of the viaduct the valley floor then consisted of

intertidal The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of Marine habitat, habitats with var ...

mudflats Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...

and a great quantity of

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

washed down from the numerous mines upstream.Restronguet Creek Society website
Retrieved June 2010Cornwall Industrial Settlements Initiative; Devoran
Retrieved June 2010 This soft layer was over thick and "...not an ideal foundation for a 96ft high viaduct." After exploratory drillings, the engineering contractors sunk cast iron caissons through the silt to the bedrock at each pier location. The cylindrical caissons, in diameter, were then emptied of silt so that masonry footings could be built from the rock up to surface level, pumps being employed to keep the workings dry. This added to the cost of construction but proved entirely satisfactory as Carnon was among the last of the original Cornwall railway viaducts to be replaced.

References

External links

* {{DEFAULTSORT:Carnon viaduct Bridges by Isambard Kingdom Brunel Railway viaducts in Cornwall

See also

References

External links