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Powerline river crossings comprise both overhead lines and cable tunnels beneath rivers and estuaries. Overhead power lines are supported on towers (called pylons in the UK) which are usually significantly taller than overland pylons and are more widely spaced to cross the river in a single span. Tall pylons ensure that the electricity cables which they support provide an adequate safety clearance for river traffic.
The tallest and longest overhead power line river crossings in the United Kingdom are:
The tallest electricity pylons in the UK are those of the 400 kV Thames Crossing, at West Thurrock, which are 190 m (630 ft) high. These were constructed by BICC in 1965. The cables stretch 1300 m (4,500 ft) across the River Thames and have a minimum clearance of 76 m (250 ft). There are two 400 kV circuits that connect Littlebrook substation on the south bank to West Thurrock substation on the north side. [1]
The longest powerline river crossing in the UK is the Aust Severn Powerline Crossing over the River Severn at Aust, stretching 1700 m (5,310 ft) between towers 148 m (488 ft) high. The line was commissioned in 1959 and comprises two 275 kV electricity circuits forming part of the line between Iron Acton and Whitson substations. [2] This pylon crossing is paralleled by the Severn-Wye Cable Tunnel beneath it, at almost the same location.
This is an incomplete list of overhead powerline river crossings in the UK.
| River | Location | Span (m) | Height of towers (m) | Clearance (m) | Notes | References |
|---|---|---|---|---|---|---|
| Blyth | Blyth, Northumberland | 389 (275 kV), 352 (66 kV) | 1 × double 275 kV, 1 × single 275 kV, 1 × double 66 kV, 1 × single 66 kV, 1 × single ? kV | [3] | ||
| Cleddau Ddu | Burton, Pembrokeshire | 583 | 1 × single 132 kV | [4] | ||
| Forth | Alloa, Clackmannanshire | 425, 462 | 2 × single 275 kV | [5] | ||
| Forth | Kincardine Bridge, Clackmannanshire | 1,130 | 137 & 154 | 1 × single 275 kV, see 275 kV Forth Crossing | [5] | |
| Loughor | Bryn, Carmarthenshire and Swansea | 406 (upper crossing), 377 (lower) | 1 × single 132 kV, 1 × single 132 kV | [6] | ||
| Mersey | Fiddlers Ferry, Warrington | 250 | 1 × single 275 kV | [7] | ||
| Ness | Inverness, Highland | 1 × double 275 kV, 1 × double 132 kV, 1 × double 132 kV, 1 × double 33 kV | [8] | |||
| Orwell | Cliff Quay, Suffolk | 417 (upper), 444 (lower) | 45 | 2 × triple 132 kV (unusual triple circuit on each crossing) | [9] [10] [11] | |
| Ouse | Blacktoft, East Riding of Yorkshire | 528 | 2 × double 400 kV | [12] | ||
| Ribble | Preston, Lancashire | 222 | 1 × double 400 kV, 1 × single 400 kV, 2 × double 132 kV, 1 × double 33 kV | [13] [14] | ||
| Severn | Arlingham, Gloucestershire | 639 + 639 | 2 × single 132 kV (crosses river twice) | [15] | ||
| Severn | Aust, Gloucestershire | 1,700 | 148 | 1 × double 275 kV, commissioned in 1959, see Aust Severn Powerline Crossing | ||
| Soar | City of Leicester | 265 | 3 × double 132 kV | [16] | ||
| Tamar & Tavy | Weir Quay & Carr Green, Devon and Cornwall | 553 (400 kV), 635 (132 kV) | 1 × single 400 kV, 1 × double 132 kV | [17] | ||
| Tay & Earn | Easter Rhynd, Perth and Kinross | 425, 380 | 1 × single 275 kV, 1 × single 132 kV | [18] | ||
| Tees | Teesport, Stockton on Tees | 542 | 1 × single 400 kV | [19] | ||
| Thames | Thurrock, Essex and Littlebrook, Kent | 1,300 | 190 | 76 | 2 × double 400 kV. Constructed by BICC in 1965. See 400 kV Thames Crossing | [1] |
| Thames | Crossness, Bexley & Dagenham, Barking and Dagenham | 933 | 148.4 | Former 132 kV. Installed 1927-32, dismantled 1987. | [20] | |
| Trent | Walcot, North Lincolnshire | 944 (upstream) 1022 (downstream) | 2 × double 400 kV | [12] | ||
| Tyne | Jarrow, Tyne and Wear | 800 | 128 | 1 × single 275 kV | [21] [22] [23] | |
| Tyne | Stella, Tyne and Wear | 524 (longest crossing) | 1 × double 400 kV, 2 × double 275 kV, 2 × double 132 kV | [24] | ||
| Tywi | Penken, Carmarthenshire | 359 (400 kV), 206 (132 kV) | 2 × double 400 kV, 1 × single 132 kV | [25] | ||
| Yare | Trowse, Norwich, Norfolk | 72.5 | 132 kV. Dismantled 2017 | [26] [27] |
In addition to overhead powerline river crossings, there are also underground powerline river crossings.
Tunnels under the River Thames, from east to west are:
Other underground tunnel cable crossings are:
The 430-ft high 275kV Tyne Crossing collapsed on 16 February 1962, on the same day there was the British highest wind speed of 177mph on Lowther Hill in south-west Scotland. [38] [39] [40] The pylon at Jarrow crashed at 4am, and the pylon at East Howdon crashed at 5.20am. The Jarrow pylon crashed onto oil pipes of the neighbouring Shell oil terminal. The North Eastern Electricity Board had planned a transmission line from Blyth to Teesside in 1958; Jarrow Borough Council wanted the cables to go underground. [41]
It was part of the 50-mile Blyth to Lackenby 275kV line. [42] The transmission line was built around December 1961. [43] The crossing was rebuilt from 4 November 1962. [44]
A transmission tower is a tall structure, usually a lattice tower made of steel that is used to support an overhead power line. In electrical grids, transmission towers carry high-voltage transmission lines that transport bulk electric power from generating stations to electrical substations, from which electricity is delivered to end consumers; moreover, utility poles are used to support lower-voltage sub-transmission and distribution lines that transport electricity from substations to electricity customers.
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Aust Severn Powerline Crossing is the longest overhead power line span in the United Kingdom with a length of 1,618 m (5,308 ft).
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