Frightening digital warning signs meant to promote road safety actually cause more crashes than they stop, economists have found.
Researchers looked at “in your face” warnings in Texas which displayed messages such as “1669 deaths this year on Texas roads”.
They found that the number of crashes in the 10 kilometres after the signs were up to 8pc higher during the weeks that the messages were shown.
The bigger the fatality number displayed and more complex the road network, the more accidents went up. The study, by the University of Toronto’s Jonathan Hall and Justin Madsen of the University of Minnesota, suggests the initiative caused an extra 2,600 crashes in Texas alone.
Across the 26 states using the signs, the authors suggest around 80 deaths a year and 13,000 extra crashes could have been caused - at a cost to society of $1.9bn.
Their research runs counter to a surging focus on behavioural economics in public policy as a cheap way of influencing people to pay tax on time, epitomised by the so-called Nudge unit which David Cameron set up in 2010.
Hall and Madsen said: “Shocking fatality messages distract drivers.
“Given behavioral interventions are intentionally designed to be salient and seize attention, the message, delivery, and timing must be carefully designed to avoid the intervention backfiring.”