Declan

The Dublin Port Tunnel is Ireland's grandest civil engineering project. 5,000 workers laboured about 8 million man-hours on the mega-project. The mechanical stars of the Port Tunnel were Gráinne and Megan, two giant tunnel-boring machines. Being mainly an excavation exercise, a massive amount of material was shifted during the 5-year enterprise. 2 million tonnes of rock and clay were moved. Drilling through hardened limestone and boulder clay is punishing and, at times, dangerous. Although there were the usual expected injuries involved in such a mammoth construction site, thankfully, none were serious, and there were zero fatalities. The hole at the Whitehall site was 56 metres in diameter and the equivalent of 7 storeys in depth. Beneath Fairview Park alone, a "cathedral-sized" cavity was hollowed out during construction. The majority of the tunnel is 22 metres underground, which unsurprisingly holds unique challenges. It is a twin-bore tunnel of 4.5km in length, the immersed tube tunnel section, with a height clearance of 4.65m. To deaden the huge noise emissions and destructive vibrations, amplified within the constricted space, the walls are fitted with acoustic panels. The hidden dangers of gas poisoning caused by the exhausts of all those vehicles in a subterranean tunnel are dealt with by a 16 jet fan ventilation system fitted with gas and fire detection sensors. A significant landscaping job on the surface was done for cosmetic reasons and to prevent erosion or sinkholes. Over 40,000 trees and shrubs were planted along the route, and around the tunnel ends. The controversial underground burrow runs from Whitehall to Fairview, connecting the M50 to Dublin Port. Unsurprisingly to any Dubliner, the construction project overran its schedule and budget, and a comedy cavalcade of ridiculous planning decisions was to follow. Former Taoiseach and underworld-dwelling grifter Bertie Ahern ceremoniously broke ground on the Dublin Port Tunnel in May 2002. The estimated cost was around €752 million, broke down to €448 million for the construction tender, and €304 million for project costs. From the very get-go, the height of the tunnels was criticised, with the project bizarrely not having sufficient clearance for HGVs higher than 4.65 m (15 ft) when a relatively minor increase to 5.5 m would future-proof it for every possible commercial vehicle. In 2006, sub-standard concrete and punctures in the protective membranes caused leaking. So far, 241 houses situated above the route successfully claimed structural damages from the €1.5 million repairs fund. These were mainly related to vibration from hard-rock boring, causing cracks and foundational weaknesses. The 5.6km long tunnel was supposed to ease congestion in the often gridlocked city by taking 10,000 trucks and HGVs (heavy goods vehicles) a day off the streets. Considering all the planning and execution mishaps, it is understandable there were allegations of brown envelopes and blank cheques aplenty! It opened to traffic on the 20th of December 2006.