Increasingly, and where possible, roads are being built in tunnels often for environmental reasons, writes Patrick Smith As part of the new M7 motorway development in the southwest of Ireland, the four-lane route crosses the River Shannon near Limerick, before it flows into the Atlantic. Centrepiece of the 10km long Limerick Southern Ring Road is the required tunnelling (675m long), which including the north and south entrance and exit ramps, means it will be 915m long. Completion of the work is planned for