Bulls Gorge on SH10 in Northland has been the site of many accidents over the years with police frequently requesting that motorists drive defensively when traveling through the area. This crash record and a number of fatalities prompted action from the New Zealand Transport Agency (NZTA) and work began in late 2010 to realign the road through the gorge replacing it with easier curves, better gradient and a wider highway with improved shoulders. CSP Pacific’s Armorwire Wire Rope Barrier System was chosen as one of the finishing touches to the realignment.
Bulls Gorge is a strategic link between Auckland and the far north for both the tourism and freight industries. Most of the work on the $7.5 million project was undertaken during the summer months to reduce environmental impact. Some 190,000 tonnes of earth was excavated and 45,000 locally sourced native plants were planted around Bulls Gorge as part of the project.
Because of the huge volumes of earthworks being carried out beside a scenic reserve, substantial environmental protection and restoration was required. “We even had tracking collars on Kiwi birds so we could confirm their safety during the earthworks operation,” said Mark Williamson, Engineer for Northern Civil Consulting Engineers. Achievement of the successful engineering and environmental objectives is testament to the great cooperative spirit between NZTA, NCC, Department of Conservation (DOC), Transfield Services and their subcontractors.
Replacement of the previous guardrail safety barrier was necessary but there was a need to maintain the aesthetic and environmental values while meeting safety performance requirements. In achieving these criteria, a wire rope option was considered superior. Studies on the use of wire rope barrier systems were reviewed with various factors considered such as: reduced ongoing maintenance and repair costs; the reduced effect of vehicle damage on impact; aesthetic appeal and environmental impact. NZTA approved the preferred design of the edge protection using CSP Pacific’s Armorwire Wire Rope Barrier.
The NZTA’s Project Manager, Ronnie Salunga explains, “originally a semi-rigid barrier was to be installed. However with the NZTA’s commitment to reduce road fatalities and injuries, the project team decided installing the wire rope flexible barrier would be a more effective safety measure on this section of highway.”
“With the gorge and the road widened, Armorwire Wire Rope Barrier offered the deflection NZTA and NCC were after,” says Will Young, Sales Engineer Central North Island for CSP Pacific.
“CSP Pacific’s Armorwire Wire Rope Barrier was used in three locations along the project,” says Graham Rush, from Splice Construction Ltd. “The engineers requested Armorwire be used to protect motorists from the bank on one side and drop offs and drains on the other. In all 1.4kms was installed with the installation going very well. The Armorwire looks good and is very effective.”
The Bulls Gorge makeover is now complete with the straighter route providing safer passage for motorists, freight carriers, tourists and cyclists.