What does side underrun protection do on trucks and trailers?

If you see bars down the side of a truck or trailer between the axles, this is side underrun protection and it's designed to stop cyclists, motorcyclists low vehicles and other road users falling, sliding or driving underneath the truck or trailer and being run over by the rear wheels.

On the Side of Safety – Bicycle NSW

Strenx® for curtain sider trailers - SSAB

New underrun protection for tippers, low bed trailers with slide

Under-Run Bars on Trucks : Why they are important for you! - Team-BHP

Rear underrun protection bar complete mounted

ATA releases side underrun protection program - Trailer Magazine

Semi-trailer truck - Wikiwand

When Is Side Underrun Protection Needed? – Bicycle NSW

SIDE ISSUE

Validating underrun devices through simulation - Smedley's

Semi-trailer truck - Wikiwand

Strenx® 960 for rear underrun protection device

Benefits of side underride guards for semitrailers