New life for old bridge

Reclaimed Australian hardwood timber is breathing new life into one of Christchurch’s oldest bridges.

Helmores Lane Bridge, the city’s only surviving nineteenth century timber bridge, will live on well past its 150 years with the help of timber salvaged from two Waitaki River bridges built in 1881.

SCIRT’s McConnell Dowell delivery team, repairing Helmores Lane Bridge, had the job in 2014 of dismantling the two Waitaki River bridges, near Kurow, and has sourced about 30 bridge piles, made of the Australian hardwood Jarrah from the Waitaki District Council for the cost of a donation, a lot less expensive than importing new hardwood from Australia for the earthquake repairs.

Washdyke miller, John McCarthy, is turning them into hand rails, posts and cross beams for the historic bridge, built in 1866 by eccentric English barrister Joseph Cornish Helmore to cross the Avon River in Fendalton to access his property block, Millbrook.

SCIRT site supervisor Jamie Stark with one of the reclaimed Jarrah beams

Using reclaimed timber fits well with the conservation practice of sourcing material as close as possible to the original for the repair and restoration of heritage structures.

Helmores Lane Bridge is listed as Category 11 by Heritage New Zealand and is the only remaining example of a propped beam timber bridge in Christchurch.

Original timber frame largely intact

While the bridge has been repaired and widened, about 80 per cent of the original timber frame, consisting of its piles and beams, remains.      

However, the original timber deck and the hand rails have been replaced over the years. The hand rails on the downstream side are being rebuilt using the original mortise and tenon joint.

“It’s a challenging project because you are trying to protect an original structure and its character while providing the protection of a modern structure,” SCIRT Executive General Manager Ian Campbell says.

New additions to old structure

The original 17-metre long bridge now requires new access ways - land spans - which will be about five metres long at each end to replace the badly damaged abutments. 

SCIRT Carpenter Reynaldo Ramos works on handrails for the Helmores Lane Bridge

“The new land spans will help protect the bridge from soil movement. The finished result will be a more resilient structure than the original,” Campbell says.

In line with conservation guidelines, the land spans, made of new timber with steel components, will complement the original bridge but look sufficiently different to be recognised as an addition.

Helmores Lane not a legal road

Before the earthquakes Helmores Lane Bridge carried vehicles but a surprising discovery by the Christchurch City Council’s legal team ends that. They found that Helmores Lane, the approach to the bridge, was stopped in 1895, that it was legally part of Hagley Park and that it was not a legal road. So, once the repairs have been completed, in about five months, the bridge will only be open to pedestrians and cyclists.

Published: 23 June 2016