Barrier suppliers

Updated: Tuesday, March 13, 2012 - 07:48

The NZ Transport Agency does not have preferred barrier suppliers and does not recommend any particular barrier products. The following list is provided as a guide to the range of barrier types that are available. The acoustics ratings are explained here, and items with an asterisk are estimates only.

Material / Product	Image	Built locations	Acoustics rating
Material / Product	Image	Built locations	A	B
Timber
Nuibarrier Modular engineered plywood wall system. It can be built over 6 m high. Manufacturer's test data: EzyShield 24mm 14kg/m² - STC24 EzyShield 33mm 18kg/m² - STC28		SH20, Maioro Street Interchange, Auckland (2011) SH18, Greenhithe, Auckland (2007)	A0	B2*
Woodtex Panels composed of woodwool impregnated with rapid hardening cement, under pressure. Manufacturer's test data shows the panels provide sound absorption in the order of 0.6 NRC.			A2*	B2*
Concrete
Litecrete Concrete Panels Pre-cast concrete Modular system, usually with steel support posts. Pumice aggregate and induced air entrainment reduces the weight of panels. Panels are 150 mm thick up to a maximum size of 7 m x 3.5 m.		Mt Hobson Road, Newmarket, Auckland (2010)	A0	B3*
Stahlton Pre-cast concrete Modular system, usually with steel support posts. Panels can span up to 8 m. Precast concrete panels with 25% recycled concrete. Acoustics test data available from the manufacturer.		SH1, Otahuhu, Auckland (2010)	A0	B3*
Ultrapanel Pre-cast concrete Modular wall panel. Panels are a mix of cement, limestone, cellulose fibre and additives, with hollow cores to reduce weight. Panels are 300 mm wide and up to 2.2 m long.		No specific noise barrier examples to date, but has been used as a fencing product within NZ. VicRoads (the highway authority for the Australian State of Victoria) has advised the NZTA that the use of these panels in noise barriers in some VicRoads projects has not been successful.	A0	B3
Hebel AAC Panels Pre-cast concrete Modular system, usually with steel support posts. Panels made from Autoclaved Aerated Concrete (AAC). 600 mm high by 100 mm thick panels are stacked horizontally and attached by clip and bolt to support posts. Panels available up to 6 m long and to heights exceeding 4 m.		Noise barrier at Martha Mine, Waihi, NZ	A0	B3*
Transparent
Plexiglas Soundstop Acrylic panel. Bird guard product includes 2 mm wide black stripes at 30 mm spacings within panel.		SH1, Victoria Park Tunnel project, Auckland (2011)	A0	B3
Composite
Speedwall Panels formed from zinc coated steel shell filled with aerated concrete. Modular interlocking panels which can be installed horizontally or vertically.		No specific noise barrier examples, but to date have been used for building sound insulation purposes within NZ e.g. cinemas, apartments	A0	B3*
Plaztuff Frabricated plastic noise walls with support columns. Interlocking panels and mounting posts.		No specific noise barrier examples to date, but have been used commercially as an alternative to steel within NZ.	A0	B3*
Panelrok Sandwich panel consisting of a foam core and two reinforced resin laminated outer skins with steel or concrete support posts		No specific noise barrier examples to date, but has been used as a fencing product within NZ	A0	B2*
BelAire Panels formed from fibre cement skins with polystyrene core. A modular system with panels fitting in slotted steel posts (280 mm wide by 140 mm deep). Composite panels are 70 mm thick, in heights of 900 or 1200 mm and lengths of 2400, 2700 or 3000 mm. Manufacturer's test data: STC 21 (NAL 2005).		Residential and commercial sites in the main centres in NZ. Noise barriers for the New South Wales Roads & Traffic Authority.	A0	B2*
Other
Rawe Stoneboxes Steel mesh cage filled with rocks, with an acoustic blanket lining. Factory filled and vibrated, double galvanised gabion with an integrated lifting system. 80 mm thick acoustic blanket embedded in the cage.		No specific noise barrier examples to date, but has been used within retaining walls NZ	A0	B3*
Onduline Sheets made from recycled paper impregnanted with bitumen, corrugated on one side. A separate timber frame is required. Manufacturer recommends cladding both sides of the frame for acoustics performance.		No specific noise barrier examples to date, but has been used as roofing, wall cladding, fencing within NZ	A0	B2*

Performance ratings

Sound absorption

The 'A' rating is defined in EN 1793-1 and relates to the sound absorbed by a barrier that would be otherwise reflected. In effect, A0/A1 means most sound is reflected, through to A4 which means most sound is absorbed. This can be significant when there are tall parallel barriers facing each other, and sound reflected from the far barrier can pass over the near barrier. The EN 1793 absorption categories are defined in the following table.

Category	DL_α
A0	N/A
A1	< 4 dB
A2	4 to 7 dB
A3	8 to 10 dB
A4	> 11 dB

Sound transmission

The 'B' rating is defined in EN 1793-2 and related to the reduction of sound passing through a barrier. B0/B1 means that the barrier is not effectively reducing sound through the barrier, through to B3 which provides the most sound reduction. (The overall performance will also be highly dependent on the barrier height.) These ratings are currently tested in a laboratory under reverberant sound conditions. International test methods are currently being developed that would use field rating instead to more accurately represent the performance for road-traffic noise, and in future it is envisiaged that the ratings in this table will be updated to that new method. The current EN 1793 sound transmission categories are defined in the following table.

Category	DL_R
B0	Not determined
B1	< 15 dB
B2	15 to 24 dB
B3	> 24 dB

Where the DL_R performance has not been stated by the manfacturer/supplier, the following process has been use to estimate its value.

1/3 octave band sound reduction index data has been used where available.
If the only data available is a single figure Rw/STC, the spectrum has been estimated using Insul software program and scaled to the quoted Rw/STC.
If no acoustics value is stated, Insul has been used to estimate the properties, and a 2 dB tolerance subtracted from the performance
Where the test has not included a post, this has been modelled with 3 mm wide leakage path running the full height of the barrier, as modelled in Insul using Gomperts' method