When selecting safety barriers for car parks it’s easy to make the mistake of thinking most steel barriers would cope with the slow speeds in a car park if they can be used on motorways? Perhaps surprisingly this is not the case.
Crashes on motorways typically hit the barriers a glancing blow whereas in car parks it’s likely to be head on. In consequence a 10 mph impact in a car park will require the barrier to withstand very similar forces to a 70 mph impact on a motorway.
Also, you don’t want to replace the barriers after every knock so they need to absorb a blow and then return to effective service. The other major difference between a motorway environment and a car park is the presence of pedestrians.
Part K of Building Regulations – Vehicle Barriers and Loading Bays – is quite straight forward because it simply requires any building with vehicular access to have barriers capable of withstanding the forces defined in BS 6399.
BS 6399 on the other hand is quite a complex, but vital document to understand when selecting barriers. It defines how the impact forces are calculated and where they act in terms of heights and distribution and how to define the weight of a typical vehicle.
BS 6180 is a code of practice for barriers in and around buildings and defines where barriers are needed, where handrails and in-fill mesh should be fitted and the heights and sizes of these.
However, these standards are quite old now and should be read in the light of recommendations from the Institute of Civil Engineers and the Institution of Structural Engineers who both produced reports in 2002 that effectively update the British Standards which were published in the mid 1990s.
These recommendations take into account changing styles and fashions within vehicle designs. For example, the popularity of 4x4s means the average height of a bumper has risen and so the typical point of impact on a safety barrier is now higher than previously.
They also looked at some key areas of risk where speeds may be higher, such as opposite the down ramps in a multi-storey car park or at the end of long aisles, and made recommendations about the forces the barriers in those positions need to withstand.
These recommendations don’t have the backing of being legal requirements but they are sensible and you ignore them at your legal peril. Some are only applicable to multi-storey car parks but most of the provisions apply to ground level, open car parks as well.
Another design change not covered by either of these reports is the trend to thinner concrete decks many of which can not take the imposed loads defined by BS 6399 through an impact on a rigid barrier system.
The new Berry Brisafe system (for new build) and our renowned spring steel buffers and Flexi-post systems are all designed to absorb impacts within the barrier and reduce pull-out loadings on the deck – as well as reducing damage to cars and the barrier itself.
They’ve all been independently tested to prove that they comply with the standards and it’s important that any barrier supplier has such test results available and is fully conversant with all the standards, regulations and recommendations.
By doing this we can reduce damage to the barriers, reduce damage to vehicles and the car park. Most important of all, we can help to protect pedestrians, drivers and passengers.