Proposals for fixed sea links to improve transportation between areas of the British Isles include undersea tunnel, bridge, causeway, or combination of these elements.
1 Proposed fixed sea links between Great Britain & Ireland
1.1 North Channel (Kintyre) route 1.2 North Channel (Galloway) route 1.3 Irish Mail route 1.4 Tuskar route
2 Proposed & existing fixed sea links between Great Britain & France
2.1 Channel Tunnel 2.2 Second Channel Tunnel or Bridge 2.3 Channel Islands Tunnel
3 Development history of Great Britain/Ireland proposed connections 4 Other proposed fixed sea links within or to the British Isles & associated areas 5 See also 6 References
Proposed fixed sea links between Great Britain & Ireland North Channel (Kintyre) route This is the shortest route at around 19 km (12 mi), from the Mull of Kintyre to County Antrim. North Channel (Galloway) route This route has been proposed variously as either a tunnel or a bridge. A 2010 report by the Centre for Cross Border Studies estimated building a bridge from Galloway to Ulster would cost just under £20.5 billion. The proposal would see passengers board trains in Glasgow then cross the bridge via Stranraer and alight in Belfast or Dublin. A longer bridge already exists between Shanghai and Ningbo in East China. Some political parties in Northern Ireland have included the bridge in their manifesto for some time. However, because of the Beaufort's Dyke sea trench, this route would be deeper than the southern routes. The sea trench was also used for dumping munitions after World War II and so would require an expensive clean up operation. Ronnie Hunter, former chairman of the Institute of Civil Engineers Scotland, suggested that the project was a "stretch but doable". He cited the lack of "soft rock, the chalk and sandstone" as a challenge compared to the construction of the Channel Tunnel. He also suggested that the change in rail gauge between Ireland and Britain might pose further concerns. It is believed[by whom?] that such a project was considered by railway engineer Luke Livingston Macassey in the 1890s as "a rail link using either a tunnel, a submerged "tubular bridge" or a solid causeway". In January 2018 leading figures in the Democratic Unionist Party revived calls for a bridge or tunnel between Larne in County Antrim and Dumfries and Galloway , the estimated £20 billion cost of the 25-mile project would make it among the biggest infrastructure projects in UK history. The link was proposed by Sammy Wilson, a senior DUP MP, and Simon Hamilton, a former minister for the party in the Stormont administration, who is touted as a future leader. Irish Mail route This route (from Dublin to Holyhead in Anglesey, Wales) would be about 68 km (42 mi) long. Tuskar route The Institution of Engineers of Ireland's 2004 Vision of Transport in Ireland in 2050 imagines a tunnel to be built between the ports of Fishguard and Rosslare along with a new container port on the Shannon Estuary, linking a freight line to Europe. This report also includes ideas for a Belfast–Dublin–Cork high-speed train, and for a new freight line from Rosslare to Shannon. This route would be approximately twice the distance of the English Channel Tunnel at over 100 km (roughly 60 miles long). Proposed & existing fixed sea links between Great Britain & France Channel Tunnel
Existing Channel Tunnel
The Channel Tunnel operates between Great Britain & France. It is a 50.45-kilometre (31.35 mi) rail tunnel linking Folkestone, Kent, in the United Kingdom, with Coquelles, Pas-de-Calais, near Calais in northern France, beneath the English Channel at the Strait of Dover. At its lowest point, it is 75 m (250 ft) deep. At 37.9 kilometres (23.5 mi), the tunnel has the longest undersea portion of any tunnel in the world, although the Seikan Tunnel in Japan is both longer overall at 53.85 kilometres (33.46 mi) and deeper at 240 metres (790 ft) below sea level. The speed limit for trains in the tunnel is 160 kilometres per hour (99 mph).
Second Channel Tunnel or Bridge
A second English channel tunnel with a road was proposed in 2000 by Eurotunnel, the motorway beneath the sea to link Britain and France could be built in the next 25 years under proposals. The ambitious project would involve the construction of the longest road tunnel in the world, containing two 46 km-long carriageways, one on top of the other, which would allow motorists to complete the journey in about 30 minutes.
An English Channel road bridge was proposed in 2018 by UK foreign secretary Boris Johnson, however with limited success.
Channel Islands Tunnel
The Channel Islands Tunnel was a proposed tunnel between Jersey and Lower Normandy. In July 2009, it was revealed[by whom?] that the States of Jersey were considering the feasibility of building a 14 miles (23 km) long tunnel to connect the island with Lower Normandy in France; the tunnel would be a concrete tube sunk in the seabed and then covered over. Talks would be held[by whom?] in September 2009 to ascertain whether it would be of local benefit. The proposition included a road and rail link. The plans were not developed, and the then Assistant Minister for Planning and Environment Deputy Rob Duhamel who had suggested the idea lost his seat in the 2014 elections.
Development history of Great Britain/Ireland proposed connections A 1799 description of a failed proposal for a bridge from Howth to Holyhead is a mocking metaphor for the failure of the Union Bill 1799, which succeeded next year as the Act of Union 1800. Between 1886 and 1900, proposals for a link to Scotland were "seriously explored by engineers, industrialists, and Unionist politicians". In 1885, Irish Builder and Engineer said a tunnel under the Irish Sea had been discussed "for some time back". In 1890, engineer Luke Livingston Macassey outlined a Stranraer–Belfast link by tunnel, submerged "tubular bridge", or solid causeway. In 1897 a British firm applied for £15,000 towards the cost of carrying out borings and soundings in the North Channel to see if a tunnel between Ireland and Scotland was viable. The link would have been of immense commercial benefit, was significant strategically and would have meant faster transatlantic travel from Britain, via Galway and other Irish ports. When Hugh Arnold-Foster asked in the Commons in 1897 about a North Channel tunnel, Arthur Balfour said "the financial aspects ... are not of a very promising character". In 1915, a tunnel was proposed by Gershom Stewart as a defence against a German U-boat blockade of Ireland but dismissed by H. H. Asquith as "hardly practicable in the present circumstances". In 1918, Stewart proposed that German prisoners of war might dig the tunnel; Bonar Law said the Select Committee on Transport could consider the matter. The Senate of Northern Ireland debated a North Channel Tunnel on 25 May 1954. In 1956 Harford Hyde, Unionist Westminster MP for North Belfast, raised a motion in the UK House of Commons for a tunnel across the North Channel. In 1980, John Biggs-Davison suggested European Economic Community involvement in a North Channel tunnel; Philip Goodhart said no tunnel was planned. In 1988, John P. Wilson, the Irish Minister for Tourism and Transport said his department estimated an Irish Sea tunnel would cost twice as much as the English Channel Tunnel and generate one fifth of the revenue, thus being economically unviable. In 1997–8, the Department of Public Enterprise refused to fund a feasibility study requested by Symonds engineering to build an immersed tube tunnel. Symonds revived the plan in 2000, with an £8m feasibility study and a £14b construction cost estimate. In 2005, the Minister for Transport said he had not studied A Vision of Transport in Ireland in 2050, published in September 2004 by the Irish Academy of Engineering, a report which included a Wexford–Pembroke tunnel. The proposal of building a bridge between Northern Ireland and Scotland is supported by the Democratic Unionist Party. DUP MP Sammy Wilson compared the idea to the approved Channel Tunnel and HS2 projects. The party made a feasibility study into a tunnel or enclosed bridge a precondition to coalition support in the event of a hung parliament in the 2015 election, and again reiterated the potential for a sea bridge in January 2018.  Other proposed fixed sea links within or to the British Isles & associated areas
A possible Orkney tunnel between Scotland and Orkney (about 9–10 miles or 15–16 km) was publicly discussed especially around 2005, but also at other times.
In 2014 a consultation was undertaken by Orkney Islands Council, with a view to considering a series of fixed links involving seven of the Orkney islands. This would include a bridge between the isles of Eday, Westray and Papa Westray, to alleviate the need for air travel - currently the shortest schedule flight in the world, and also from Orkney to Shapinsay, Egilsay, Rousay and Wyre, but not a tunnel to Scotland this time.
A bridge from mainland England to the Isle of Wight has been proposed a number of times, often due to the high cost of ferries to and from the island. The Isle of Wight Party - a political party active only in the Isle of Wight - was set up with the intention of campaigning for a fixed crossing. Critics have suggested that such a link may damage the ecology of the Isle of Wight, particularly the red squirrel population. Campaign group Pro-Link has put forward a number of plans to the Isle of Wight Infrastructure Task Force of the Isle of Wight council, including a £1.2 billion four mile long dual-carriageway tunnel in the Solent between Whippingham on the island and Gosport, Hants. The campaign group has proposed the project be initially run on a toll basis, but that it would have paid for itself after eighteen years. In 2017 Abel Connections Ltd released their plans for the project, "to create a new north-south axis through the centre of the Solent region by constructing a tunnel from the M27 east of junction 9 to the Whippingham roundabout on the Isle of Wight, with an additional access intersection ‘cut and cover’ portal near the mainland coast between Browndown and Meon." 
In 2008 the Liverpool Echo ran an article suggesting the construction of a 75 mile bridge to the Isle of Man from Liverpool. Despite the proposal being nothing more than an April Fools joke, the bridge was included in an engineering text book called the "Handbook of International Bridge Engineering" in its 2017 print.
Rail transport in the United Kingdom Rail transport in Ireland Cross-sea traffic ways Strait of Gibraltar crossing
^ a b Castella, Tom de (14 August 2013). "A bridge across the Irish Sea and four other amazing plans" – via www.bbc.co.uk. ^ "Could a bridge or tunnel one day link Scotland with Ireland?". ^ "Bridge to Northern Ireland mooted". BBC News. 22 August 2007. ^ http://www.scotsman.com/business/companies/could-a-bridge-or-tunnel-one-day-link-scotland-with-ireland-1-4130353 ^ http://www.eveningtimes.co.uk/news/13307549.Building_bridges___literally__Unionists_plan_for_link_between_Scotland_and_Ulster/ ^ http://www.scotsman.com/business/companies/could-a-bridge-or-tunnel-one-day-link-scotland-with-ireland-1-4130353 ^ http://www.eveningtimes.co.uk/news/13307549.Building_bridges___literally__Unionists_plan_for_link_between_Scotland_and_Ulster/ ^ McKenzie, Steven (9 October 2011). "Scotland-Ireland undersea rail link plan 'a surprise'". BBC News – Highlands & Islands. Retrieved 5 February 2012. ^ http://metro.co.uk/2018/01/24/bridge-built-scotland-northern-ireland-7255433/ ^ A Vision of Transport in Ireland in 2050, IEI report (pdf), The Irish Academy of Engineers, 21 December 2004. ^ http://www.eurotunnelgroup.com/uk/the-channel-tunnel/infrastructure/ ^ Millar, Stuart (6 January 2000). "Tunnel chiefs unveil road link to France" – via The Guardian. ^ No 10 unenthusiastic about Boris Johnson's Channel bridge plan (19 Jan 2018 ) ^ http://news.bbc.co.uk/1/hi/world/europe/jersey/8149314.stm ^ http://jerseyeveningpost.com/news/2008/10/18/bridge-to-france-study-next-year/ ^ http://www.ouest-france.fr/un-projet-de-tunnel-pour-relier-jersey-la-manche-524626 ^ "Plans for a Bridge from Holy-Head to the Hill of Howth". The Anti-Union (20): 80. 9 February 1799. JSTOR 30059887. ^ Hughes, Kyle (2013-12-01). The Scots in Victorian and Edwardian Belfast: A Study in Elite Migration. Edinburgh University Press. pp. 128, fn.39. ISBN 9780748679935. Retrieved 25 September 2015. ^ "Tunnel Under the Irish Sea". Irish Builder and Engineer. Howard MacGarvey & Sons. 27: 197. 15 July 1885. ^ "Scotland-Ireland undersea rail link plan 'a surprise'". BBC News. 9 October 2011. ^ "Tunnel Under the Sea", The Washington Post, 2 May 1897 (Archive link) ^ "TUNNEL (IRELAND AND SCOTLAND)". Hansard. 22 March 1897. pp. HC Deb vol 47 cc1125–6. Retrieved 25 September 2015. ^ "IRISH CHANNEL TUNNEL". Hansard. 23 February 1915. pp. HC Deb vol 70 c168. Retrieved 25 September 2015. ^ "TUNNEL TO IRELAND". HC Deb vol 110 c594. 22 October 1918. p. Hansard. Retrieved 25 September 2015. ^ "North Channel Tunnel". Parliamentary Debates: The Senate. Vol.38. Parliament of Northern Ireland. 1955. pp. 513–531. ^ "An Irishman's Diary" by Wesley Boyd, (Link), The Irish Times, Feb 2004 (subscription required) ^ "IRISH CHANNEL TUNNEL". Hansard. 23 March 1956. HC Deb vol 550 cc1641–88. Retrieved 22 September 2015. ^ "Irish Sea (Tunnel)". Hansard. 4 February 1980. pp. HC Deb vol 978 c85W. Retrieved 25 September 2015. (Link has incorrect question; correct question is on preceding page with incorrect answer) ^ "Written Answers. - Sea Transport". Dáil Éireann debates. 16 November 1988. pp. Vol.384 No.3 p.34. Retrieved 22 September 2015. ^ a b "Plan to build rail tunnel under sea". 7 April 2000. Retrieved 29 September 2015. ^ "Written Answers — Ireland-UK Tunnel". Dáil debates. 29 March 2000. Retrieved 22 September 2015. ^ "Written Answers - Transport Projects". Dáil Éireann debates. 15 February 2005. Retrieved 22 September 2015. ^ "Could a bridge or tunnel one day link Scotland with Ireland?". www.scotsman.com. Retrieved 2017-03-06. ^ "Building bridges - literally: Unionists plan for link between Scotland and Ulster". Evening Times. Retrieved 2017-03-06. ^ "Election 2015: DUP votes 'may be vital' in forming government". BBC News. 2015-04-21. Retrieved 2017-03-06. ^ http://metro.co.uk/2018/01/24/bridge-built-scotland-northern-ireland-7255433/ ^ £100m tunnel to Orkney 'feasible' (10 March 2005) ^ http://www.scotsman.com/news/transport/orkney-bridge-plan-may-end-world-s-shortest-flight-1-3443317 ^ http://www.bbc.co.uk/news/magazine-23587557 ^ https://www.thesun.co.uk/news/1887023/plans-to-build-1-2billion-tunnel-to-the-isle-of-wight-unveiled-as-an-alternative-to-slow-car-ferries/ ^ http://iwradio.co.uk/2017/05/19/latest-isle-wight-fixed-link-plan-revealed/ ^ http://www.liverpoolecho.co.uk/news/liverpool-news/fictional-bridge-between-liver