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Report on testing vehicle windscreens

Objects deliberately dropped from overpasses into the path of vehicles travelling on high-speed roads pose a risk of serious injury to drivers and passengers.

The area of greatest risk to motorists is the penetration of objects through the front windscreen.

The department has conducted tests to determine appropriate aperture sizes for screening on overpass structures to reduce the likelihood of damage from big objects being dropped. Both concrete and steel spherical projectiles were used during testing.

Impact resistance of vehicle windscreens 
Report that describes the tests performed during and recommends a maximum aperture size for overpass screening.

Technical guidelines for the treatment of overhead structures 
Guidance on assessing potential risk of objects being thrown from overpass structures, and technical design criteria for preventative measures. 

Reduction of risk from objects thrown from overpass structures onto roads 
Departmental policy that provides direction to reduce or prevent objects being thrown from overpass structures.

Last updated
17 March 2021