Sir, - Mr Gerard Murphy, the project engineer for the Dublin Port Tunnel, challenges my information on the issues, yet fails to answer the relevant questions (December 24th). He refuses to face up to the reality that there will be a major increase in traffic in the East Wall Road. Professor Simon Perry of TCD's school of engineering has already warned that there would be major traffic congestion in the North Wall and East Wall areas because of the volumes of traffic exiting from the port tunnel. Why does Mr Murphy ignore this up to date accurate information? He also ignores the recent statement of Mr Aidan Phillips, professor of geology, that there was "a major fault zone" running across the Fairview end of the route.

While the geological profile of Marino would appear to show approximately 10 metres of boulder clay over limestone, the problem areas are the pockets of waterlogged gravels and sands. Drillings have showed that these exist and are approximately 3/4 metres high. Water inflow and high seepage where a NATM meets or disturbs these saturated pockets is one of the major causes of NATM collapses. Mr Murphy is well aware that there have been 39 major incident/collapses in NATM tunnels under construction between 1973 and 1994. Some of these involved loss of life. I was present at meetings when Mr Murphy accepted these as facts. A question mark must now be hoisted on this whole project on safety grounds.

To say that this tunnel will lead to a significant improvement in air quality is blatant misinformation. All objective observers know that it will decrease air quality and increase noise levels. It will pass directly under 273 homes at a depth of 16 metres in the Marino area. These people have rights and deserve fair play. Above all they deserve accurate information from Mr Murphy and Dublin Corporation. - Yours, etc.,

342 Charlemont,

Griffith Avenue, Dublin.