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Tough wear it matters

With Transport for London’s new Bus Safety Standard demanding mandatory slip-resistance test values after six months in situ, measures relating to ex-factory slip resistance are no longer enough to rely on.

In step with the demands of service

Flooring specifically engineered for use in heavy duty buses will be built to withstand wear, but how much wear does it need to be able to tolerate? How much wear is too much?

In an average London bus, an area of concentrated foot traffic could see 230,390 steps per year.1 Even in quieter services outside London, buses could see an average of 2,993 steps per month in concentrated areas of foot traffic, adding up to 35,916 steps in a year.

Good to know, but what does this all mean for sustained slip resistance?

Pendulum test values and slip risk

Pendulum test values are indicative of the potential slip risks associated to a particular surface. The Bus Safety Standard requires a floor to provide a pendulum test value of ≥36 from new, rising to PTV ≥40 after six months of service. This mitigates slip risks to one in a million. Specifying a floor covering with a lower value can significantly reduce this level of protection and leave passengers and operators open to additional risk.

PTV Estimated slip risk*
36 1 in 1,000,000
34 1 in 100,000
29 1 in 10,000
27 1 in 200

*According to CIRIA’s Safer Surfaces to Walk On

So, if you choose a floor with a pendulum test value of between 29 and 33, you could potentially be risking two slips per month in the Greater London area. Even with a floor with a pendulum test value of between 34 and 36, you’d be risking two slips per year. Only with a pendulum test value of 36 or higher would you be assured of mitigating the risks associated with the level of foot traffic experienced in a heavy bus environment.

If you want to find out more about the Pendulum test, read our guide here.

Sustained safety

But, mitigated risks are still dependent on the floor in question sustaining its pendulum test value at 36 or higher for the period of its service life.

Testing with a machine such as the Pedatron is the best way to accurately emulate wear on a floor.

The Pedatron imitates the step of a person by repeatedly subjecting the floor to friction from a rubber soled shoe with the same weight behind it as would be expected from an average male human.

Look for a floor which has aggregate distributed throughout the thickness of the wear layer. This means that as the wear layer wears away, the components which create the slip resistance are always in contact with the soles of the shoes walking on it. With floors built this way, slip resistance may improve with wear.

Beware of additives that are sold as an extra wear layer to increase the slip resistance of the floor – once this extra layer has worn away, what are you left with if the material beneath fails to meet PTV ≥36?

Altro bus flooring products are engineered to maintain a one in a million slip risk, even after one million steps, without the need for any added slip-resistant layers.

1According to Transport for London figures for 2017.
Posted: 08/05/2019 08:00:00 by Heather Mussett | with 0 comments