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    Technical drawings: NZTA standard detail – Semi-rigid guardrail on a convex curve

Technical drawings: NZTA standard detail – Semi-rigid guardrail on a convex curve

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The New Zealand Transport Agency (NZTA) has prepared two drawings detailing the correct installation of guardrail on a curve or in a curved rail terminal situation. These drawings cover all new installations and maintenance situations.

The intermediate anchor used in both these details is to provide tension for the downstream rail. If the intermediate anchor is not used then there is a risk that an errant vehicle could penetrate the guardrail system. This could result in death or serious injury.

The Curved Rail Terminal detailed in NZTA drawing RSB-2 is a cost effective solution to terminating a semi-rigid guardrail system into a secondary or access - effectively closing out the hazard.

The Rail on Curve detailed in NZTA drawing RSB-2A is required on guardrail installed on a tight radii, 25m or less to ensure adequate protection of the errant vehicle from the hazard.

The details are available from the NZTA website:

Click here for technical memorandum.

Click here for technical drawings.

If you have any enquiries regarding these details please contact the National Traffic & Safety Engineer, Highways & Network Operations, NZTA National Office or

The main points:

  • For convex curve only
  • Curve radius is 25m down to 5m (standard increments of 5m)
  • Intermediate anchor must be used at the each end of the curve
  • Clear area behind the curve is a minimum of 22.0m x 6.0m
  • Three apex posts are required with the location depending on most likely impact directions

CSP Pacific has adapted these details for use with our proprietary semi-rigid guardrail system, Nu-Guard 31™ Steel Post Guardrail System and they have been accepted by NZTA for use on the State Highway network.

To view the Nu-Guard 31™ Rail on Curve and Curved Rail Terminal drawings click here.


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