Thames Cable Tunnel

{{short description|Tunnel carrying high-voltage cables beneath the River Thames between Tilbury and Gravesend}}

{{Use dmy dates|date=April 2022}}

{{more citations needed|date=March 2020}}

{{Infobox power transmission line

| name = Thames Cable Tunnel

| country = UK

| owner = National Grid plc

| current_type = AC

| AC_voltage = 400 kV

| type = Underground tunnel

| est = 1970

}}

The Thames Cable Tunnel, also known as the Tilbury – Gravesend Cable Tunnel, is a tunnel carrying high-voltage electrical transmission lines beneath the lower River Thames between Tilbury and Gravesend. It remains the furthest tunnel downstream on the Thames.{{Cite journal|last=Anon|date=May 1970|title=Cables Down Under|doi= 10.1049/ep.1970.0161|journal=Electronics & Power|volume=16 |issue=5 |pages=175}}

Completed in 1970 at a cost of around £3 million (equivalent to £{{Inflation|UK|3|1970|cursign=£}} million in {{Inflation/year|UK}}) by the Central Electricity Generating Board, the tunnel carries 400 kV transmission cables between substations at Tilbury and Kingsnorth as part of the National Grid. The tunnel is approximately {{convert|45|m}} deep, and was one of the first tunnels in the UK to be lined with pre-cast concrete segments rather than cast iron. A tunnel was chosen due to the high costs of building an overhead transmission line at this point in the river.{{Cite journal|last=Haswell|first=C.K.|date=December 1969|title=Thames Cable Tunnel|journal=Proceedings of the Institution of Civil Engineers|volume=44|issue=4|pages=323–340|doi=10.1680/iicep.1969.7250}}

In September 2023, National Grid announced that they were planning to retire the Thames Cable Tunnel, as it was approaching the end of its useful life. The Grain to Tilbury project aims to construct a new tunnel to replace it.{{Cite web |title=National Grid launches consultation on planned Grain to Tilbury infrastructure upgrades |url=https://www.nationalgrid.com/national-grid-launches-consultation-planned-grain-tilbury-infrastructure-upgrades |date=2023-09-27 |access-date=2023-12-12 |website=www.nationalgrid.com}}