Swamp was no problem

Press, Volume CX, Issue 32486, 22 December 1970, Page 14

Swamp was no problem

One of the biggest problems confronting the construction of the Christchurch Northern Motorway was coping with a deep swamp between Belfast and Tram Road. Instead of going around it as some people thought, Ministry of Works engineers decided to go through it. To make this possible 750,000 cubic yards of gravel had to be lifted from the Waimakariri River to build the motorway 22ft above the surrounding land.

To make sure the motorway had a solid foundation, at least 15ft of gravel was formed into a road and in places the height rose to 22ft.

When the gravel was 15ft thick its weight was one ton to the square foot. The huge gravel moving operation gave work for hundreds of privately owned trucks in Christchurch and district.

For many months whole fleets of trucks operated a shuttle service from the dredges on the river banks to a stockpile which bulldozers finally moved into place. The motorway also created big business for suppliers of pre-stressed concrete in the form of

piles and bridge beams. One firm alone made more than 2000 tons of piles and 2700 tons of beams. The decking for the Waimakariri bridges alone used 7000 cubic yards. Mile for mile the motorway and its bridges has been one of the cheapest roadways built in New Zealand. The ready availability of materials and the speed at which they could be brought to the site made the cost much lower than similar work in other parts of the country.