Thrie-Beam is tested and accepted to NCHRP350 Test Level 3 (TL-3) with timber posts and blockouts and NCHRP350 Test Level 4 (TL-4) with "I" section steel posts and modified steel blockouts.

CSP supplies Thrie-Beam guardrail with a base metal thickness (BMT) of 2.7mm and in standard net lengths of 4 metres with post spacing at 1m centres.



Thrie-Beam is roll-formed from coil steel and sheared to length. It is then punched, slotted to suit the particular configuration and hot dip galvanised in accordance with AASHTO Specification M180 and AS/NZS 3845:1999.


Thrie-Beam is available ex-stock in standard effective lengths of 4.00 metres and 2.00 metres.

Curved Thrie-Beam

The standard straight section will align to give a smooth transition on curved with a radius greater than 45m. Pre-curved Thrie-Beam is required for tighter radii and may be curved to traffic face concave or convex - refer to table in technical information.


Thrie-Beam complies with the requirements of:

  • NCHRP350 TL-3 and TL-4 when used as an approved system
  • AS/NZS 3845:1999 - Road safety barrier systems
  • NZTA specifications M/23 and M/17P.