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Median Barrier Drury to St Stephens, SH, Akl
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Designer: Connell Wagner
Contractor: Fulton Hogan - Main Contractor
Troy Wheeler Contracting - Installation
Product: Thriebeam™

The modified Thriebeam™ system complies with NCHRP 350 Test Level 4. In addition, it can contain an 8000kg single unit truck at 80 km/h - making it the safest system available.
The Project

Vehicles breaching the median barrier on Auckland's motorways have always been a serious issue - the stretch from the Drury overbridge to the bottom of the Bombay hills is no exception, with only a wide grass strip running between the two flows of traffic. This month, the installation of a median barrier down the centre of the 6 km stretch of motorway has begun in order to provide greater protection for motorists.

The Solution

CSP Pacific's Thriebeam™ product was specified for 3.3km of the project. The modified Thriebeam™ system is the first median barrier installation of its type in New Zealand. The Thriebeam™ is mounted on a modified steel block (see picture) which is deeper than the standard block to prevent vehicle wheels snagging on the posts after impact. The Thriebeam™ solution consists of 1.5 kilometres of single sided barrier, which utilises a steel C section post imported from Australia, and 1.8 kilometres of double sided barrier featuring a steel I section post from the USA. Both posts are driven into the ground directly, making installation quick and easy.

A key advantage of the modified Thriebeam™ system is its high spec - it complies with NCHRP 350 Test Level 4 and can contain a 2000kg vehicle travelling at 100km/h at an angle of 20 degrees. In addition, with the post and block modifications, this system can contain an 8000kg single unit truck at 80 km/h - making it the safest system available. The Thriebeam™ barriers are being installed in conjunction with a wire rope system. The wire rope system will be used in areas where the grass strip median allows a deflection of up to 3.5m either side of the barrier. Thriebeam™, on the other hand, is used in areas where deflection needs to be minimised to 1m or less.


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