New South Wales' Roads and Traffic Authority (RTA) has completed its Intelligent Speed Adaptation (ISA) trial, the largest of its kind ever conducted by a government agency in Australia.
Developed to examine the effectiveness of ISA devices in improving compliance with speed limits, the voluntary trial involved over 110 vehicles owned by non-government fleets and private motorists.
Through a navigation-like device installed in the vehicle's dash, the Intelligent Speed Adaptation system uses GPS technology to monitor the vehicle's position and speed, alerting motorists when they are exceeding the posted speed limit.
The driver is alerted by both visual and auditory feedback, and if they continue to exceed the speed limit, the system will automatically restrict engine power until the vehicle returns to the allowed speed.
Speaking with the ABC earlier this year, British Professor of Transport Safety Oliver Carsten said that a similar trial in the UK showed promising results.
"We're talking up to a 30 percent reduction in injury accidents, and 50 percent reduction in fatal accidents," Prof Carsten said.
"Participants did have control of their vehicle, and we also had an override function on the system. Drivers could override the system, and one of the interesting things was to look at who disabled the system and who didn't."
"The effect on speed proved to be pervasive. Everybody had their speed modified. People were driving less over the speed limit, and very high speeds were curtained drastically."
According to the NSW RTA, the trial has successfully proven the potential for Advisory ISA technology to deliver "considerable" road safety benefits.
In results released this week, the trial showed that with the ISA system activated, 89 percent of participants reduced the amount of time spent exceeding the speed limit.
Interestingly, 86 percent of participants returned to some level of speeding with the system deactivated, but not to the same levels observed in the 'Before ISA' period. The median percentage of time spent speeding reduced in the 'During ISA period from 36.3 to 24.1 percent, but increased in the 'After ISA' period to 30.5 percent.
The NSW RTA report said that many participants in the trial came to rely on the device to inform them of the speed limit and when they were exceeding it, with some "using it almost like a form of cruise control."
The results also showed that younger drivers were significantly less likely to alter their driving behaviour with the ISA system installed, with only 77 percent of drivers under 25 responding to the alerts - compared to 93 percent of motorists over 25.
Many participants described the ISA device's beeping alerts as annoying and irritating, and expressed frustration toward its 'unforgiving' response to travelling a few kilometres per hour over the speed limit.
This frustration is mirrored in recent studies that have shown a strong social acceptance of 'low-level speeding', and the ISA trial acknowledged that these attitudes likely contributed to the frustration of its participants.
The report added that a "significant future challenge" for the technology will be in slowing people down in situations where they perceive a need to speed, such as being late to an appointment.
Many participants of the trial, and in earlier studies, have expressed a belief that they should not be fined for travelling a few kilometres per hour over the speed limit. Because the ISA system is expected to be voluntary if introduced to the public, it is expected that many drivers may choose to disable the system in these situations.
The RTA believes that if the ISA system were used by all motorists in New South Wales, there would be an approximate 8.4 percent reduction in fatalities and a 5.9 percent drop in injuries.
Based on recent history, these figures equate to around 35 lives saved each year and 1455 people escaping injuries on the road. It would also lead to a saving of around $370 million per year in related costs.