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The Jack Lynch Tunnel (Irish: ''Tollán Sheáin Uí Loingsigh'') is an immersed tube tunnel and an integral part of the N40 southern ring road of Cork in Ireland. It is named after former Taoiseach, Jack Lynch, a native of Cork. It takes the road under the River Lee. North of the tunnel, the ring-road joins the M8 motorway to Dublin (north) and N8 road to the city centre (west), with the N25 commencing east to Waterford. The tunnel was completed in May 1999, and carried nearly 40,000 vehicles per day as of 2005. This number rose further as the N40 ring-road's upgrades progressed, with the opening of the Kinsale road roundabout flyover in 2006 and the recently completed upgrades to the Sarsfield Road and Bandon Road Roundabouts. Traffic in 2015 is 63,000 vehicles a day up from 59,000 in 2013. 〔(【引用サイトリンク】url=https://www.nratrafficdata.ie/c2/calendar_alt.asp?sgid=ZvyVmXU8jBt9PJE$c7UXt6&spid=NRA_000000001256 )〕 The tunnel has two cells, each with two traffic lanes and two footpaths, and a central bore for use in an emergency only. Pedestrians and cyclists are expressly forbidden from using the tunnel. The exclusion of cyclists has been somewhat controversial as the feeder road is a dual-carriageway and so is open to cyclists, but the bye-law is applied because of space limitations and the obvious danger of cyclists in an enclosed tunnel. ==History== The idea of a crossing of the River Lee downstream of the city came from civil engineers employed by Cork Local Authorities and the central government's Department of the Environment in the late 1970s. Cork's suburbs were expanding and traffic was rising as car ownership increased, but the city centre's street plan, laid out in the late Middle Ages, was ill equipped to cope. The engineers reasoned that the congestion in the city centre and its radial routes was quickly reaching intolerable levels. They pushed through Cork's "LUTS" – Land Use and Transportation Study – plan,〔Greater Cork Area Land Use/Transportation Study. Skidmore, Owings & Merrill, the MVA Consultancy, and LUTS Team. Cork 1976〕 to lay down a twenty five-year plan for the orderly growth of transport and land use in the greater Cork area. The transportation proposals combined construction of elements of a ring road, a downstream crossing, and computerised management of traffic on existing roads. This group of engineers became the Technical Steering Committee for the LUTS Plan and at that time consisted of Sean McCarthy, the former City Engineer, W.A. "Liam" Fitzgerald, his successor as City Engineer, Liam Mullins, Cork's County Engineer, John O'Regan, his deputy, B.J. O'Sullivan, the Cork Harbour Engineer, and Sean Walsh and Declan O'Driscoll, the two Assistant Chief Engineering Advisers at the Department of the Environment responsible for the region.〔Bardas Chorcai; Down-Stream Crossing of the River Lee, Feasibility Study. DeLeuw Chadwick O'hEocha,Consulting Engineers, November 1981〕 The location and type of crossing was not established by the LUTS plan. No road development in Ireland prior to that date had required such a large investment,〔Seanad Éireann – Volume 122 – 17 May 1989 Adjournment Matter: Cork City River Crossing. http://historical-debates.oireachtas.ie/S/0122/S.0122.198905170009.html〕 and therefore the plan met with some opposition on the grounds of cost. In 1980, Cork Corporation commissioned DeLeuw Chadwick O’hEocha, engineering consultants, to undertake a feasibility study of options for a major highway crossing of the River Lee downstream from Cork city centre. A team led by J.D. Shinkwin, Director of DeLeuw Chadwick O’hEocha, performed the study.〔 The first stage of the report established that the crossing should be located in Dunkettle, rather than at Tivoli, closer to the city centre. The second stage endorsed an immersed tube tunnel as the preferred scheme versus a bridge (either fixed or opening span). The primary reasons were that a tunnel would have a lower construction cost relative to its utility, shorter approach gradients, lower environmental impact and no effect on shipping once built. While the construction costs for a two lane tunnel were marginally higher than for a two lane high-level bridge, the steep upward ramp for a high-level bridge would slow down cars and trucks as they climbed the bridge, thus reducing its peak capacity dramatically versus a tunnel〔 or, alternatively, necessitating the addition of a climbing lane with significant additional costs. The other alternative considered by the Steering Committee was an opening span bridge. While this solution would avoid the ramp problem of a high-level bridge, traffic would halt whenever the bridge had to open. Shipping volumes into Cork's port area was rising steadily in the 1980s, which meant that an opening span bridge was becoming less attractive every year. A sworn Public Inquiry into Cork Corporation's application for a "bridge order" providing for a two-lane tunnel was held in October 1985. The required inspector's report was submitted in January 1987 to the then Minister of the Environment, Pádraig Flynn. At that point, the report remained on the minister's desk for some time. The formal reason for this was that the minister "decided that the question of the timing of the crossing should be considered in the broader context of the preparation by the Department of proposals for the medium to long term development of national roads. In this context the operational programme for roads … includes the proposal for the commencement of the downstream crossing during the programme period 1989–1993".〔 In 1989, the government recommended a further feasibility study to consider the need for a crossing and the technical, economic and operational aspects of the various crossing options. The study confirmed the findings of the original Feasibility Study. A further Public Inquiry was held, with hearings in July and December 1990, which considered further the alternative of a four lane crossing rather than the planned two lane crossing. In 1992, the Minister approved a Bridge Order for a four lane immersed tube tunnel. In the intervening time, the Irish government had also established the National Roads Authority (NRA) to advance the long term development of the national roads network. Declan O'Driscoll was appointed the Chief Engineer of that authority and together with J.D. Shinkwin, Director of Ewbank Preece OhEocha, and W.A. Fitzgerald, Cork City Engineer, formed an informal Technical Steering Committee for the Tunnel Project. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Jack Lynch Tunnel」の詳細全文を読む スポンサード リンク
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