A new web video from the Insurance Institute for Highway Safety (IIHS), "Inside IIHS: Side testing," explains a crash test that has helped drive progress in occupant protection.

When IIHS first began crashing a 3,300-pound barrier into the sides of vehicles a decade ago, the tests revealed structures that allowed severe intrusion into the occupant compartment. Today's vehicles protect occupants much better, thanks to stronger safety cages and side airbags, IIHS said.

The video shows the deformable barrier, which has the shape and height of the front end of a typical SUV or pickup truck. The barrier is crashed into the sides of vehicles at 31 mph, and SID-II dummies positioned in the test vehicles represent a small woman and a 12-year-old child. IIHS Vice President Raul Arbelaez walks viewers through the test and explains how the results are translated into ratings.

The video is available on the IIHS YouTube channel and is part of the "Inside IIHS" series. Previous installments have focused on other IIHS tests, crash test dummies, the propulsion system used to power crash tests, and IIHS’ booster seat rating program.