Auckland Regional Office

29 January 2003

MEDIA RELEASE

Massive Railway Bridge Successfully Moved In Hours

Auckland anniversary weekend saw Transit New Zealand undertaking unusual engineering work in Auckland city’s Grafton Gully. In a major operation, a 1900 ton pre-constructed rail bridge was shifted 15 metres sideways from a temporary sliding platform to its permanent location on the corner of Stanley St/Beach Rd/The Strand.

The weekend’s activities, which virtually created a new, fully operational rail bridge within a matter of days, were undertaken on behalf of Transit by the Freeflow consortium.

A critical element of the Grafton Gully motorway project, the new structure will pave the way for the realignment of one of Auckland’s busiest intersections. When completed, traffic northbound on Stanley St will continue straight ahead, under the new bridge, and will connect directly with The Strand, so removing the current dogleg turn through Parnell Rise.

Transit Regional Manager Wayne McDonald explains that what appeared to be a three-day operation required a great deal of planning, preparation and co-ordination even before the bridge was built. As a result, the design and construction teams worked closely and integrated temporary requirements for the installation within the overall bridge design.

This approach proved successful and a number of modifications to the permanent design helped ensure that the bridge installation went smoothly.

Once the railway tracks were closed on Friday night, contractors worked on a very tight schedule to dismantle the old tracks and embankment before the bridge could make its short but impressive journey.

Built on a teflon-coated sliding system, the bridge was then shifted sideways some 15 metres with the help of hydraulic jacks pulling on eight 32mm diameter tie-rods attached to the bridge. Started at about 10am on Saturday morning, the bridge was shifted into its permanent location in less than six hours!

During the operation, the temporary slide system was removed with the help of eight heavy-duty hydraulic jacks with a combined capacity of 3000 tons. These lifted the 1900-ton bridge, together with temporary steelwork, and new railway tracks, and lowered it all 150mm onto the permanent bearings to allow the structure to be fully connected.

While shifting a bridge is rare, Transit opted for this method because a temporary detour of the existing rail line was not a feasible alternative. “We were also constrained by the embankment and existing rail bridges on either side,” explains Wayne McDonald.

“Therefore, we had to use an installation process that could be implemented within a brief line closure.” To minimise disruption to rail traffic, the line closure was scheduled for a long weekend.

While the train service recommenced as scheduled, taking passengers on the Newmarket line over the new bridge, motorists will have to wait until the new alignment is completed later in the year before being able to drive under the bridge.

ends

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