The relocation of the 124- year-old Rob Roy Hotel (known as the Birdcage from the 1980s) at the end of August marked a major milestone for the NZ Transport Agency (NZTA) and A pub crawl with a difference the Victoria Park Alliance as part of the construction of the Victoria Park Tunnel.

The heritage-listed brick building was slowly pushed along specially built concrete runway beams to a temporary position 44 m along Franklin Road, where it will remain for approximately six months. It will then be pushed back to its original location which will then be on top of the southern entrance to the new motorway tunnel.

Built in 1885–86 mainly from brick and concrete, the Rob Roy Hotel has huge heritage value for Auckland as it marks the original foreshore, when Freemans Bay was a busy industrial area, with shipbuilders, sawmills, a foundry, glass and asphalt works, and many coal and lime dealers. Most of the original structure remains intact, and the redbrick façade and decorative plasterwork on the window and door surrounds are still in their original state.

Transit New Zealand (now the NZTA) bought the Rob Roy in 2002 as the site was needed for extension of the motorway. The hotel will eventually be restored as part of a plaza at the intersection of Franklin Road and Victoria Street West in Freemans Bay when the tunnel is completed in 2012.

Exceptional engineering challenges

The actual move of the Rob Roy was the climax of six months of painstaking planning and preparation, says the NZTA’s state highways manager for Auckland, Tommy Parker. “The proposal to move the building presented exceptional engineering challenges because of the age of the hotel and the fact that it was built from unreinforced brick masonry. A structure like this has very little seismic strength and is inherently brittle, so any settlement or subsidence could cause major cracking.”

Work by the Victoria Park Alliance to prepare the Rob Roy for its move involved extensive structural strengthening of the building and providing a new foundation on which the building would rest.

The rear walls (with no heritage value) were sheathed with reinforced concrete to brace the exterior. Structural diaphragms were installed at the first floor and roof level to ‘tie’ the building together, and high-tensile steel bars were inserted through holes coredrilled into the other exterior and interior brick walls and then tensioned. The chimney was also secured with carbonfibre reinforced strips.

A new rigid foundation was built by casting ‘sandwich’ beams on either side of the exterior and interior brick walls, and then stressing these together to act as a single unit. Excavations were then carefully made under the building and below the ‘sandwich’ beams, and four ‘runway’ beams were cast – these became the 44 m long ‘causeway’ along which the Rob Roy was moved.

Transferring the load

With the building fully strengthened, its weight was then slowly transferred to hydraulic flat jacks inserted between the foundation sandwich beams and the runway beams at the 14 points where the beams intersected. These jacks were carefully monitored before and during the move to ensure the building remained completely level. Beneath each jack was a sliding bearing, consisting of a low-friction Teflon ‘puck’, and this slid along a stainless strengthened, its weight was then slowly transferred to hydraulic flat jacks inserted between the foundation sandwich beams and the runway beams at the 14 points where the beams intersected. These jacks were carefully monitored before and during the move to ensure the building remained completely level.

Beneath each jack was a sliding bearing, consisting of a low-friction Teflon ‘puck’, and this slid along a stainlesssteel strip that was fixed to the top surface of each runway beam, thus easing the building’s movement along the causeway.

Two days prior to the move, and with the flat jacks bearing the 600 tonne load of the building, the old foundations were cut away.

With the teams set to go, the big push got underway at 7.30am on 31 August. Two hydraulic rams bolted onto the runway beams slowly pushed the building forward up to 1.8m at a time. After being retracted and rebolted further along, another cycle was commenced. In this fashion, the Rob Roy was slowly and gently muscled along the runway beams. The biggest risk was the chance of ground movement below the runway beams, Mr Parker says. “The building had to remain level, and we achieved this through continuous monitoring and very tiny adjustments of hydraulic pressure within the flat jacks.”

Slow progress

Progress was painfully slow initially, with just 3 m achieved by midday. The team had projected the move would take just a day, but the Rob Roy was less than halfway to its new home when failing light caused the proceedings to stop at 6pm. Work resumed the following morning, and by the end of the second day, the Rob Roy was safely and securely in its new temporary location.

The move was carried out under the guidance of Wellington company Dunning Thornton Consultants which was responsible for moving the Museum Hotel to make room for Te Papa. Consultant design engineer for the move, Adam Thornton, says speed was not the issue. “The important thing was that we got the Rob Roy to the other end, unstressed.”

With the Rob Roy in its temporary home further along Franklin Road, work continues apace on the Victoria Park Tunnel. It’s a satisfactory result for the
NZTA. “There were plenty of people who said it could not be done, that the building should have been torn down,” Tommy Parker concludes, “but the Rob Roy has survived one move, and while there are still challenges ahead, we are confident that it will survive the return journey.”

A timelapse video of the Rob Roy move.