Just over four years of complex and demanding civil engineering construction, as well as approximately ten years of advanced planning and design, came to fruition on Friday 21st May 1999 with the completion of the Jack Lynch Tunnel. The official opening was performed by the Taoiseach, Mr. Bertie Ahern T.D. in the presence of the Lord Mayor, Councillor Joe O'Flynn and the Chairman of Cork County Council, Councillor Kevin Murphy.
The gala ceremony was attended by over 600 invited guests, including members of the Lynch family. The Tunnel was jointly blessed by Bishop John Buckley and Bishop Paul Colton. A guard of honour was provided by the Naval Service and the band of the First Southern Brigade provided a fitting musical accompaniment. The event was celebrated with parties in local schools in Mahon, Blackrock and Little Island, with 50 pupils from each school also attending the tape cutting ceremony.
The official opening was followed on the weekend of 22nd and 23rd May by a charity walk through the tunnel organised by the Rotary Clubs of Glanmire and Douglas. This one and only opportunity to walk under the River Lee, as for safety reasons pedestrians are precluded from using the tunnel under normal circumstances, captured the imagination of the people of Cork city and county and from even further afield, as an estimated 100,000 people completed the walk over the two days. The Rotary clubs themselves raised over £100,000 for selected charities, with many other organizations and community groups organising their own fund raising around the event. After a further week of staff familiarisation and safety exercises carried out by the Garda Siochana and Cork City Fire Brigade, motorists began to reap the benefits of this £100 million scheme, when the tunnel was opened for normal traffic on Monday 31st of May. Since then on average about 33,000 vehicles use the tunnel each weekday, with about 28,000 vehicles per day at weekends, and the tunnel and the associated ring road network has significantly reduced traffic congestion in the city centre.