We’ve been watching government departments around Australia installing concrete blocks and traffic crash barriers in pedestrian locations – would you recommend these as being secure and safe?

GOOD question and we think the answer depends. A concrete block would likely stop a car travelling at up to 60kmph without moving far – but it might move metres after the impact. However, in a truck strike, concrete blocks are likely to end up being shifted some way down a mall or pedestrian walk. Depending on the nature of the strike, their shape and low centre of gravity will help minimise this. 

Upright concrete crash barriers are a different story. They weigh about 2500kg so you’d think they would provide good safety. However, they have a high centre of gravity and their relatively tall and flat facia means most the energy of an impact will be transferred to them. 

If an un-bedded road barrier is struck square on by a heavy vehicle at speed it will become a 2500kg skittle that may harm people on the sterile side. Worse, the nature of the impact would be unlikely to disable the truck. Water barriers work, but they are huge and painful to manage. Purpose-built embedded bollards designed to transfer all the impact back into the body of the vehicle that strikes them are by far the best option for defending public spaces. 

Properly installed they will tear a heavy vehicle to pieces.♦