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Road safety barriers are designed to provide a high level of road safety by containing and redirecting errant vehicles and thereby preventing them from leaving the road. A range of barrier systems are available for use in both permanent and temporary situations. All road safety barrier products must be accepted by the NZ Transport Agency for use on state highways.

For further information on road safety hardware systems accepted for installation on the state highway network, please refer to Specification M23.

The following technical information is available:

Frequently asked questions: barriers and terminals

Technical memorandum TM-2000: FAQ barriers and terminals, provides a list of frequently asked questions (and answers) in regard to road safety barrier systems, terminals and crash cushions. This technical memorandum will be updated periodically as questions are asked and answered.

Lapping of W-Beam guardrail (TM2002) December 2011

Technical memorandum TM2002: lapping of semi-rigid guardrail provides advice on the recommended practice for the lapping of semi-rigid barrier systems (W-Beam and Thrie-Beam).

Nesting of W-Beam and Thrie-Beam guardrail (TM2003) December 2011

Technical memorandum TM2003: nesting of semi-rigid guardrail provides advice on the recommended practice for the nesting of non-proprietary semi-rigid barrier systems (W-Beam and Thrie-Beam). Refer to manufacturer for nesting details for proprietary semi-rigid guardrail systems. Refer also to NZ Transport Agency standard drawing RSB-4.

Buried-in-backslope end treatment (TM2004) December 2011

Technical memorandum TM2004: buried in backslope end treatment provides advice on the recommended practice for the design and installation of a buried-in-backslope end treatment. Refer also to NZ Transport Agency standard drawing RSB-1.

Weak barrier post backfill (TM2005) December 2011

Technical memorandum TM2005: weak barrier post backfill provides advice on the recommended practice for using low strength concrete around guardrail posts that are installed in hard surfaces such as concrete footpaths.

Curved guardrail terminal (TM2008) May 2012

Technical memorandum TM2008: Curved W-beam guardrail terminal provides advice on the recommended practice for the design and installation of a curved W-Beam guardrail terminal for radii between 5m and 15m. This design has been developed from crash tested systems and are acceptable for new installations, as well as for improving safety at existing sites. These designs are most appropriate for use on low volume highways. Refer also to NZ Transport Agency standard drawing RSB-2.

Road safety hardware system testing (TM2009) November 2012

Technical memorandum TM2009: road safety hardware system Testing provides advice on the updated testing requirements for new road safety hardware systems or significant variants of existing road safety hardware systems to be installed on the state highway network. Note that this technical memorandum relates to the testing of only. For selection of appropriate containment levels and determination of length of need, please refer to Technical Memorandum TM-2001 selection of barrier containment (test) level and length of need calculation.

Safety barrier test level and length of need (TM2001) November 2012

Technical memorandum TM2001: Safety barrier test level and length of need provides advice of the preferred method of selecting road safety barrier containment (test) level, calculating the length of need (LON) appropriate to that test level and highlighting circumstances under which the LON may be reduced.

Bridge W-Beam guardrail status (TM2010) June 2013

Technical memorandum TM2010: bridge W-Beam guardrail status details advises on the status of bridge W-Beam guardrail, its phase-out and accepted (restricted) future use.

From July 2013, bridge W-Beam guardrail is no longer to be used for new installations on state highway structures. Repair of existing installations is permitted where the level of damage does not warrant system replacement.

Pipe handrails and fences (TM2011) June 2013

Technical memorandum TM2011: pipe handrails and fences provides advice on the recommended practice for the mitigation of hazards associated with tubular handrails commonly installed for pedestrian/cyclist protection adjacent to roadways and on structures. This includes older tubular rail “barrier” systems on bridges with or without an adjacent footpath.

Ground beam for semi-rigid guardrail (TM2012) April 2014

Technical memorandum TM2012: ground beam for semi-rigid guardrails provides advice on the recommended practice for the design and installation of a ground beam for the support of semi-rigid road safety barrier systems.

Note: this design applies to public domain systems only. For equivalent details for proprietary barrier systems, contact the system supplier.

Wire rope safety barrier (WRSB) transitions (TM2013) November 2014

Technical memorandum TM2013: WRSB transitions provides advice on the recommended practice for the design and installation of transitions between wire rope safety barriers (WRSB) and semi-rigid and rigid barrier systems.

The RSB-7 series standard drawings show details of the accepted configurations for transitions from wire rope safety barrier (WRSB) to semi-rigid guardrail and rigid safety barrier systems as described in Technical memorandum TM2013.

NOTE: these configurations are generic. For specific details for proprietary barrier systems, contact the system supplier.

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