The country's highest man-made structure will reign over Dublin's O'Connell Street any day now. But how will it be put in place? Shane Hegarty finds out
What is Ireland's tallest structure? At the moment it's a crane on Dublin's O'Connell Street waiting patiently to install the Spire of Dublin. At 140 metres high, it is the tallest crane ever seen in Britain or Ireland. It is unlikely we will see anything of its height in our lifetimes again.
After it departs, we will be left with the relative dwarf that will be the Spire. At 120 metres, it will be twice the height of Liberty Hall and seven times the height of its neighbour, the GPO. The logistics of erecting it are not simple. Would you like to be known as the person who planted a crooked Spire in the centre of Dublin?
Currently in six pieces, shrink-wrapped in the offices of its Dungarvan engineers, when the go-ahead is given each piece will be transported individually to the capital, late at night to avoid traffic.
The first section will be 20 metres long, and three metres in diameter, and while the giant crane grabs one end of it, another crane will slowly drop it into a vertical position. It will be lowered into a concrete plinth in the ground, where three levelling jacks will ensure it does not become the Leaning Tower of Dublin.
The spire is founded on reinforced concrete piles, which reach down about 10 metres beneath O'Connell Street. It will take a day for the grouting around the base to dry before the second piece can be installed. Subsequent pieces will be attached to each other through internal flanges, bolted together by engineers who have access via an internal stairway. The sixth and final piece, 500 mm diameter at its tip, is too narrow to hold a staircase and will be screwed into position. The timetable will be at the mercy of wind conditions. As it is, the height of the crane means that it is tucked away each night for safety. While the lower pieces of the Spire can be erected in a moderate wind, a breeze at ground level would mean the wind at the top would be too much for the final section. The 140 metre crane automatically shuts off during these conditions.
After that, according to project engineer Michael O'Neill, "It's basically maintenance-free". There will be regular security checks to ensure no-one has broken into the staircase, as well as checks to clean up any dirt or leaves that may get in. There will be checks to make sure such equipment as the aviation light and the sensors which monitor vibrations are working properly. Changing a light bulb will involve a system of internal pulleys. There are also sensors on each bolt holding the sections together to ensure they don't loosen.
"Conceivably we can erect the whole structure over a four-day period," says city architect Jim Barrett, "and at one stage we thought about doing that so that everyone would go away for the weekend and come back and find the Spire in place. We thought it would make a good surprise. But there were health and safety issues that prevented that, but we're still looking at doing it in eight or nine days."
The plan is that it will be completed sometime between now and Christmas. A stencilled design is being applied to the lower part of the Spire, while the rest of the monument is being polished, but every detail has to be okayed with the architect. "On a normal contract, a week's delay wouldn't mean much," says O'Neill. "But this is different, and small things hold us up. A week means a lot." After waiting this long, however, most Dubliners will be amazed to see it at all.