In response to rider concerns about the safety of white line bumps, Transport for NSW conducted tests with a range of riders and found concerns may have been overstated.
The raised bumps of thermoplastic material in painted lines are called audio-tactile line-markings (ATML) and sometimes erroneously called ripple or rumble strips.
In May 2018, riders and the Motorcycle Club of NSW raised concerns about ATLMs in the centre and side lines of two sections of the Oxley Highway, saying they were slippery, dangerous and “madness”.
“They are slippery, wet or dry and will make a motorcycle unstable at the slightest contact,” said a former council member.
In response, the Transport for NSW Centre for Road Safety invited motorcyclists to ride over ATLMs in a variety of conditions in a study observed by the Motorcycle Council of NSW and facilitated by independent consultant Safe System Solutions Pty Ltd.
The study began last year and involved a pre-test survey, practical session at the Crashlab in Huntingwood, NSW, and post-test survey and discussion.
Five motorcyclists with a range of riding experience rode over the bumps in straight lanes and on curves, in wet and dry conditions, while braking and accelerating at speeds up to 95km/h. First-aid officers were on site.
Each rider was asked about their perception of safety of ATLM before a practical session riding on ATLM at Crashlab, and then again after the practical session.
After the practical session, all of the participating motorcyclists reported higher confidence in riding over the strips.
Their perception of the safety of the strips on a scale of one to 10 went from 6.75 in the dry to 8.6 and from 5.45 in the wet to 7.60.
Safe System Solutions Research and Evaluations Lead, Dr Tana Tan says riders should still be wary of the road bumps.
“Riders who understand that ATLMs are not as detrimental to a motorcycle’s stability and handling as first thought are still likely to be aware of the presence of ATLMs but perhaps not be as concerned about them as before,” says the Honda VTR1000 rider.
“I would still encourage riders to not ride over them on purpose and treat them as they would any other line marking.”
Centre for Road Safety executive director Bernard Carlon says they will continue to “work closely with peak motorcycling groups” and monitor locations where ATLMs are installed.
“The marking is particularly effective in managing driver fatigue, one of the leading causes of road crashes in NSW,” he says.
“As we continue to monitor the locations where ATLM has been installed, all road users, including motorcyclists, can benefit from the marked improvement in safety they offer.”
The requirements for materials of ATLM are provided in the Roads and Maritime QA Specification R145 Pavement Marking (Performance Based).
The performance requirements in R145 are for dry and wet retro-reflectivity, skid resistance, colour, colour change, luminance factor and degree of wear.