RAMSHIELD® W-Beam Guardrail

RAMSHIELD® w-beam guardrail safety barrier achieves a controlled redirection of errant vehicles by releasing the w-beam guardrail from the post at an optimal load to retain rail height, limit dynamic deflection and to allow the post to collapse without tripping the vehicle.

The separation of the w-beam guardrail from the post is achieved by a release tab incorporated into the post. The tab is designed to pull forward and tear from the post and remains connected to the rail to ensure there is no debris from the system that may otherwise present as a danger to other motorists.

RAMSHIELD® uses standard w-beam guardrails and standard M16 fasteners.

RAMSHIELD® w-beam guardrail has been fully crash tested and evaluated according to the specifications for MASH Test Level 3.

The crash test matrix for longitudinal barriers evaluated in accordance with MASH Test Level 3 requires the following impacts:

• 2270kg pick-up truck travelling at 100km/h and 25 degrees; and
• 1100kg passenger car travelling at 100km/h and 25 degrees.

An elective impact has also been performed on RAMSHIELD® w-beam guardrail when installed 200mm (measured from back of post) to the hinge point of a 2H:1V embankment slope. This crash test was performed with a 1700kg vehicle travelling at 110km/h and 25 degrees to reflect Australian road conditions.

The Manual for Assessing Safety Hardware (MASH) is an update to and supersedes NCHRP Report 350 for the purposes of evaluating new safety hardware devices. MASH is also the basis of testing procedures for road safety systems as stated in AS/NZS 3845.1: 2015 Road Safety Barrier Systems and Devices.

The introduction of MASH follows changes to the vehicle fleet, researching of real-life impact conditions and updated criteria for evaluating barrier performance. Most products tested to the superseded NCHRP Report 350 standard do not pass MASH testing. Australian State Road Agencies require MASH compliance for all new safety barrier installations.

Upon a vehicle impact, RAMSHIELD® w-beam guardrail will deflect. It is therefore necessary to provide sufficient distance between the barrier and the hazard to accommodate the expected dynamic deflection of the system.

The recorded MASH TL3 deflection with posts at 2m centres was 1.56m. The MASH test parameters, such as the test vehicle, impact speed and angle combination, point of impact, test matrix, etc., are designed to represent the worst, or most critical, conditions.

Safe Direction has evaluated RAMSHIELD® w-beam guardrail deflections at various post spacings, speeds and impact angles. Please contact Safe Direction for further information.

State Road Agency guidelines typically require the distance from the hinge point be sufficient to
accommodate the barrier’s design deflection and provide adequate lateral support for the system. However, on constrained sites, the barrier may be required to be positioned near or at the batter hinge point.

The sole reliance on crash testing for these applications has the potential to be misleading or misconstrued since crash test results may only be relevant to the specific soil conditions and corresponding post lateral support of the crash test installation. Therefore, at these locations, it may become necessary to install longer posts combined with reduced post spacing. Alternately a thrie-beam system providing reduced system deflection and a wider lateral catching area may be the preferred barrier system. Please contact Safe Direction for further information.

Typically, RAMSHIELD® w-beam guardrail posts are driven directly into natural ground. There is no concrete required. The posts may also be driven directly into deep lift asphalt or installed into narrow holes drilled into rock.

Where underground services or obstructions prevent the installation of the RAMSHIELD® w-beam guardrail posts to full depth, one of the following options can be considered:

• A single 6m span without posts;
• Construction of a ground beam and installing RAMSHIELD® posts on base plates; or
• Adopting a post embedment depth of 600mm in combination with reducing post spacing to 1m centres.

Please contact Safe Direction for further information.

RAMSHIELD® has been crash tested to MASH Test Level 3 at w-beam guardrail heights of between 730mm and 820mm. If future asphalt overlays are predicted, Safe Direction recommends setting the w-beam rail 820mm above road level while positioning in the bottom of the post hole slot.

The 90mm height differential (820mm – 730mm) together with lifting the rail to the top of the post slot (48mm adjustment) will therefore cater for up to 138mm of future overlays.

The design of RAMSHIELD® positions the w-beam guardrail below the top of the post, eliminating a potential snag point for motorcyclists. The post is also designed with no exposed edges.

At site locations where there is risk of impact from a dismounted, sliding rider, RAMSHIELD® may be installed with BIKER-SHIELD™ Motorcycle Barrier which is positioned below the w-beam guardrail and shields the guardrail posts.

A W beam guardrail is a barrier system installed along roadways, designed to contain and redirect errant vehicles and prevent run-off-the-road crashes. The guardrail beam resembles a W profile.