| Safety Barrier Design |
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| Written by Paul Hansen | |
MASH makes Safety Barrier Design InterestingThe annual TRB (Transport Research Board) conference was held in San Antonio in the first week of June 2009. Academic institutions have been researching the effects of the changes to the MASH standard. Manufacturers have been designing and testing new products to the MASH standard. It will be of interest that the substantially higher impact loads required under MASH TL3 and TL4 test standards have caused the “stiff post” guardrail concept to reach a design limit. Concerning wire rope safety fences, it will also be of interest that as the energy of the impact increases the all important interaction between the rope and post reaches a limit. The rope-post interaction is important to the deflection of the fence, and it is a matter of getting the design right – if there is insufficient interaction between the rope and posts then the deflection is too great, if there is too much interaction then the ropes may break before the tension can stretch the ropes to the desirable extent or the posts may not release from the ropes and become a hazard. Manufacturers are seeking to design and test products that are MASH TL4 acceptable and yet allow safety in a small car impact. Under the NCHRP350 TL4 standard the impact severity of the TL4 test was 132.3kJ. However under the MASH TL4 standard the impact severity of the TL4 test is now 209.3kJ. The 8t truck has increased to a 10t truck, and the impact speed has increased from 80kph to 90kph. This 58% increase in impact energy is just one factor that is making life interesting for road safety product designers. What will the introduction of this new MASH standard mean for road users? When MASH tested equipment starts to appear on Australian roads the products will be superior to what is currently being used. The MASH testing is more thorough and is broader in the requirements. Brifen decided to start new product development with a clean sheet. This is the first major product development for Brifen in 5 years. The aim is to have a fully tested Brifen product not only to the new MASH TL4 standard, but to the European EN1317 H2, available in the market place within 12 months. For further information on Brifen wire rope safety fence products contact Paul Hansen (02) 9631 8833. |
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| Last Updated ( Saturday, 12 September 2009 ) |
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