Jack Lynch Tunnel

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The Jack Lynch Tunnel (named after the former Taoiseach, Jack Lynch) is an immersed tube tunnel and an integral part of the N25 southern ring road of Cork in Ireland.

It takes the road under the River Lee. North of the tunnel, the ring-road joins the N8 road to Dublin (north), and the city centre (west), with the N25 continuing east to Waterford. The tunnel was completed in 1999, and carries nearly 40,000 vehicles per day as of 2005, this figure is increasing every year and may rise further with the N25 ring-road being upgraded, notably with the recent opening of the Kinsale road roundabout Flyover and planned flyovers on the Sarsfield Road and Bandon Road Roundabouts.

The tunnel has 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 only a dual-carriageway and so is open to cyclists, but due to space limitations and the obvious danger of cyclists in an enclosed tunnel this decision is understandable.

[edit] Construction

Southbound approach to the tunnel

Plans for a downstream crossing of the River Lee have been active since the late-1970s, construction work began in 1994. Construction involved the excavation of a large casting basin where the tunnel elements or pieces were constructed. After construction of elements was complete, the casting basin was filled with water and joined to the adjacent River Lee, each element was floated out and sunk into position into a carefully dredged river bed. The road surface was laid and the tunnel opened for traffic in 1999.

The tunnel transports traffic in two bores, each with two lanes of traffic, with traffic flowing in usual dual-carriageway style. During periods of maintenance one bore may be closed and the other used for bi-directional traffic.

Despite the cost of its construction and operation the tunnel is not tolled. But tolls could be introduced in the future on the Northbound bi-lane, which is suitable, having the required space and roundabout free tailback capacity.