We've all been driving and come upon signs warning us that construction is happening and we have to slow down for the safety of workers and that penalties are going to be doubled. We see billboards with children imploring us to reduce speed because their parents are highway construction employees.

Then it turns out that there is no construction. Speed limit credibility is put to the test by those instances and as a result, people have been routinely ignoring speed limits, according to Dr. Ross Blackman, a scholar at Queensland University of Technology Centre for Accident Research&Road Safety - Queensland, who presented the findings at the Occupational Safety in Transport Conference on the Gold Coast in Australia.

"It's seen as crying wolf. If people are asked to slow down at roadwork sites but find there is no roadwork being undertaken they become de-sensitised to the signage and ignore speed limits,"
Blackman
said. "In 2013, our research found that at three Queensland rural roadwork sites, the majority of vehicles observed exceeded the posted speed limits by at least 5km/h." 

Blackman's survey involved more than 400 people who were asked to estimate their speed for a range of different roadwork site scenarios, some of which were inactive sites and others with road workers visible.

"We found when a road worker and machinery were visible, drivers nominated lower speeds, suggesting that they were far more likely to slow down than if they saw no activity," he said. "There was about a 20 per cent reduction in speed between an inactive roadwork site (53km/h) compared to an active site with workers visible (42km/h)."

Blackman said despite reduced speed limits, crash rates and crash severity around roadwork sites were high because drivers failed to slow sufficiently and were often not paying attention.

"Roadwork sites have high crash rates and there have been numerous fatalities at roadwork sites in Queensland involving workers and public road users," he said.

Blackman said the study reinforced moves by the Queensland Government to review speed limit signage around roadwork sites, but cautioned that hazards may also remain outside of work hours, requiring reduced speed limits around the clock at some sites.

"There are no simple solutions, but multiple measures used in combination may be most effective. With technology, for example, variable speed limit signs can be easily changed without the need for workers to physically move or replace traditional static signage," he said. "There are also feedback speed displays which record and display how fast a vehicle is traveling, which drivers respond to well.

"Our survey showed road workers on site had the biggest impact on drivers to reduce speed, while the most effective specific measure was having police visually present and potentially conducting enforcement.

"If we can combine the effective measures, then we are more likely to see drivers reduce their speed, which will improve safety for both drivers and workers."