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Impact absorbing columns

Impact absorbing columns

Impact absorbing columns are an important safety feature of many roadways, but what do they do and how exactly do they work?

In Australia we use 2 main types of frangible columns, which are columns that break or deform upon a vehicle impact. Slip base columns break off at the base so that the vehicle can continue relatively unimpeded, where impact absorbing columns are designed to restrain the vehicle safely, which reduces the vehicle occupant’s chances of injury while preventing the vehicle from continuing on and hitting pedestrians or other roadside furniture.

Impact absorbing columns work by having vertical slots which allow the column to flatten out and then fold over the vehicle like a ribbon. This deformation slows the vehicle in a controlled manner within a couple of meters.

This video gives a good idea of what happen in the split second when a vehicle impacts one of these columns. In this Vicroads TCS-014-3 test a 1200kg car impacts the column at 60km/h, and is stopped in about 2m, averaging about 6G over the whole impact.

Impact Absorbing Column Crash Test (click to play)
The initial moment of impact.

After the 60km/h impact the vehicle damage is minimal.


Crash testing is one of the most fun things you can do as a lighting column designer, but also a critical part of improving safety on our roads.