The development of prefabricated engineered timber bridges by Big River Group, has provided a cost effective and timely solution to replacing bridges with minimal disruption to the local community. Source: Timberbiz
Big River Group’s latest bridge replacement project at Cheviot Hills Road, Drake near Tenterfield NSW, saw the replacement of an old timber bridge used to access a number of rural residential properties, with a prefabricated bridge built off-site which was craned and dropped onto the bridge’s foundation in just seven minutes.
The traditionally made timber pole and timber sleeper deck on the old bridge had been in service for some time to allow vehicles on Cheviot Hills Road to cross Plumbago Creek, and had become run down, rickety and a high concern for Tenterfield Council. 
As this bridge provided quick access into town, an efficient solution was sought so as not to interfere with local residents’ day to day commuting. This ruled out a lengthy concrete bridge construction.
Big River was able to provide assistance by prefabricating the bridge at Big River Grafton, which included Big River engineered bridge girder beams, plywood bridge decking and engineered bridge kerbing.
The majority of the road surfacing was also completed in the factory which meant that the only site works required would be to remove the old bridge structure and lower the prefabricated bridge into place before completing any height variance road works that were necessary. 
This meant the old bridge could be pulled up and the new bridge installed in the same day. “In fact, the road was closed at 7am and reopened just eight hours later when the job was completed. The pre-fabricated bridge was craned into place and was a perfect fit,” said Big River’s Grafton General Manager, Jason Blanch.
“It is all about strength to weight – light and strong. The solution for old timber bridges and girders that are in bad condition, is to remove the old deck and put in a super lightweight engineered deck, one that meets all the requirements and standards and stiffen them up for a much longer life.”
The new engineered timber girder is around 22% lighter, 35% stronger and 5% stiffer than a traditional F22 hardwood girder. The decks are a combination of treated radiata and Queensland hoop pine, while the girders consist of treated softwoods and hardwoods.
So far, Big River has installed and completed timber bridges across Queensland and northern NSW, offering a viable option for both maintaining timber bridge networks and for new bridge construction for local access, forestry access and fire road service.
Tenterfield Council has commented that this was a perfect solution for this bridge with minimal disruption, low cost and a certified structure provided for years of service to come, so the council is looking at this format as their go-to solution for same day bridge replacements.
