Roadside advertising distracts drivers and new-generation billboards that move or are well lit can be a safety threat, an analysis of international research shows.
The report by Austroads, which represents all Australian road authorities, including Main Roads, said regulations for most Australian roadside advertising had not kept pace with new billboards, particularly digital displays.
"It is now widely recognised that distraction is a significant contributor to crashes," the report said.
Though the focus had been on mobile phones, there was more recognition of distractions outside the vehicle and convincing studies showed advertising might cause poorer vehicle control.
"With the emergence of digital technology, advertising scenes can change frequently . . . and it is this potential for movement that is of special concern," it said.
The report comes as the State Government reviews road advertising laws and considers leasing freeway land for billboards.
It is understood billboards - that could earn about $120,000 a year - would be considered for freeways only on Perth's outskirts where there is enough land. Prime Kwinana Freeway locations, in front of Parliament House or on the river's edge would not be considered.
The Austroads report said there was no doubt roadside advertising with "movement or changes in luminance" could capture a driver's attention.
Roadside environments cluttered with advertising could also make it difficult to see relevant, driving-related signage.
The report said "emotional or engaging" advertising could also impair driving performance.
A Main Roads spokeswoman said the current contribution of roadside advertising to crashes was likely to be relatively minor. But new digital billboards could increase driver distraction.
"The Austroads report provides guidance on design and placement for digital billboards to minimise driver distraction," she said.
"Main Roads is reviewing its existing guidelines and, where appropriate, will incorporate the recommendations into the review."