Taking the safe direction

from Roads & Infrastructure March 2020

Protecting pedestrians

MEETING AUSTROADS’ NEW SAFETY BARRIER PRODUCT SUBMISSION CRITERIA WITH MSKT BARRIERS HAS BEEN SIMPLE, ACCORDING TO SAFE DIRECTION, WHICH HAS SEEN AN INCREASED DEMAND FOR ITS LATEST END TERMINAL. S afe Direction’s Manual for Assessing Safety Hardware (MASH) Compliant Sequential Kinking Guardrail End Terminal (MSKT) is the most recent successor to the SKT terminal. First introduced in 1997, the SKT was a highly sought-after road barrier solution across the globe.

The Australian/New Zealand Standard AS/NZS 3845 by Austroads has historically used NCHRP-350 guidelines for its testing protocols.

The SKT was compliant to NCHRP-350. However the latest version, the MSKT, is now compliant to the new MASH guidelines. A revised version of AS/NZS 3845 included MASH guidelines in 2015 but a recent change saw Austroads adopt this into its eligibility criteria.

From 1 January 2020, guardrail barriers and guardrail end terminals have had to comply with new guidelines and test criteria. The new standards follow the MASH guidelines by the American Association of Highway and Transportation Officials. MASH is being used by Austroads as the basis for assessing the submitted crash test evaluation of new products. Some of the key characteristics of the update include changes to test vehicles to reflect modern cars. Additionally, changes to the number and impact conditions of the test matrices requires testing for vehicle impacts at different angles, increasing from the existing 20 to 25 degrees.

Safe Direction is the exclusive Australian distributor of the MSKT, and started distributing its predecessor, the SKT in 2012.

Hayden Wallace, Managing Director of Safe Direction, explains that when subjected by the Virginia Department of Transportation to shallow impact angles on the nose, the SKT performed outstandingly well.

“The MASH system is just a further advancement on that. There’s not a lot of changes because it was already such a stable and functional system,” Mr. Wallace says.

The MSKT was introduced in March 2019 well ahead of the 1 January changeover to MASH to ensure the market could familiarise themselves with the system and make the transition seamless.

The MSKT End Terminal is an energyabsorbing, tangential guardrail end terminal, designed to minimise the severity of impacts occurring at the end of road barrier systems. Its especially crafted for direct attachment to a W-beam guardrail and complies with MASH Test Level 3.

The main difference with the MASH compliant terminals over the NCHRP-350 compliant terminals is that MASH terminals have a greater capacity for side on, or redirection impacts and safety improvements for shallow impact angle on the front end of the terminal. Mr. Wallace says the system is also highly applicable to smaller vehicles.

During a head-on impact, the MSKT impact head slides over the W-beam guardrail. The W-beam is sequentially kinked as it moves through the head and exits away from the traffic face. The kinking action of the rail then absorbs the kinetic energy of the impacting vehicle, gradually bringing the vehicle to a controlled stop. As the impact head slides over the W-beam guardrail, the bolted hinged posts at post locations 1 and 2 yield at collapse at ground level, contributing to a soft impact for vehicles and their occupants.

“The head itself has been engineered for optimal performance and its length is key to the stability of the rail during a collision,” he says.

Mr. Wallace says the system has also been crash tested in accordance with MASH for transition from the RamShield W-beam guardrail system to the MSKT terminal.

The system is available in MASH TL2 or TL3 Terminal configurations, applicable to applications up to 70 km/h and greater than 70km/h respectively. The tangential design feature of MSKT allows it to be installed parallel to the roadway, minimising installation time and sparing the associated costs of earthworks and site grading. For more information, contact 1300 063 220 or head to www.safedirection.com.au

Safe Direction Managing Director Hayden

Wallace says the MSKT safety barrier has been incredibly well received by road asset managers.