Last pour on viaduct

Waimarino Bulletin, Volume 4, Issue 39, 17 March 1987, Page 1

Last pour on viaduct

In just three months, trains will be traversing the newly erected Hapuawhenua Bridge which is presently in the final stages of construction. The civil engineering division of Fletcher Construction Company Ltd won the $6 million tender for the bridge that will replace the old Hapuawhenua viaduct. The old viaduct was constructed in 1908 and is not strong enough to take the weight of the new 1 1 2 tcnne electric locomotives that will shortly be using the tracks. The old viaduct is to be

stripped of its tracks and used as a walkway under the responsibility of the Department of Lands and Survey. Work began on the new viaduct in April 1985 and last week saw construction workers pour concrete into the final pier of the viaduct, which was later celebrated with much jollity and champagne. Over 5000 cubic metres of concrete have been poured into the viaduct's superstructure of 21 piers which appear amazingly slender. Pier 8 is the largest of the supports and has the capac-

ity to resist severe earthquakes with the aid of builtin ball bearings that move fractionally with tremors and thus avoid stress cracks in the structure. The first span was built in December 1985 and work has progressed well since then. A unique girder system of 60 tonnes of steel support was the base for the spans when the concrete was poured. It is the first time the design has been used in New Zealand although the 'false work girder system' is common overseas. Contd. on back page

Last pour on viaduct

Contd. from page 1 The new system enabled some of the spans to be constructed in as little as eight days, which is impossible to achieve with the conventional method of bridgeconstruction where cranes are used to install the spans. The viaduct spans 420 metres of solid concrete and steel reinforcing. Most deck spans have 10 cables running through them which are tightened to a tension of 230 tons each. There are 750 tonnes of steel reinforcing running throughout the viaduct. The deck had to be constructed in 20 metre lengths and it took on average 10 days for each deck pour.

Two crews oi construction workers totalling 35 men, including a lot of local labour, joined forces to work on the last leg of the viaduct, all who worked long hours to do the job. A fleet of concrete mixers from Byford's Readi-Mix in Taihape made the hauls to and from the site and kept up a steady flow of concrete. The Ohakune-Horopito deviation will be the last part of the main trunk line to be electrified, for which no date has been set. The communication and signal boxes for electrification will be installed by Westinghouse, McKenzie and Holland Ltd., while the electrification poles will be erected by McConnell Dowell. As well as the replacement of the viaduct, the eight kilometre stretch of line from Ohakune to Horopito had 12 curves of track altered. They were the tightest curves on the line and needed to be eased. The Taonui Viaduct was replaced and the Haere Maire Viaduct will be replaced by a culvert. Hurlstone Earthmoving Ltd won the tender for moving some of 750,000 cubic metres of earth along a stretch of the main trunk line.