As crash avoidance features make their way into mainstream vehicles, one advanced technology to help drivers avoid speeding-related crashes is still on the sidelines. It's called intelligent speed adaptation (ISA), and research indicates that it could help drivers keep their speeds in check.
ISA systems use GPS to link a vehicle's position to digital maps that include speed limits to determine if a vehicle is exceeding them by a preset amount, which drivers can specify in some cases. Some newer systems use cameras to read speed limit signs. What happens next depends on the ISA. The most common scenario involves an audible or visual alert telling the driver to slow down. Some ISA systems give a haptic alert via the accelerator that makes it increasingly harder for the driver to depress the pedal. Intervention systems can reduce engine throttle to automatically decelerate a vehicle.
ISA differs from the more familiar speed limiters on commercial vehicles and buses. Speed limiters, or governors, prevent a vehicle from traveling faster than a predetermined maximum speed. With an ISA, drivers can specify the warning threshold depending on a road's speed limit and can switch off the devices.
To promote the technology, the European New Car Assessment Programme (Euro NCAP) counts ISA systems as one of the safety features automakers can use to qualify vehicles for Euro NCAP Advanced. Models that have earned the designation so far haven't been fitted with an ISA (go to www.euroncap.com/rewards.aspx). In the United States, the National Highway Traffic Safety Administration (NHTSA) doesn't include the technology among the crash avoidance features it recommends in the New Car Assessment Program.
Although ISA systems haven't been deployed on a large scale on private vehicles in the United States or Europe, the devices have been studied for more than 20 years. Several studies, including two recently published ones, point to potential benefits.
Warnings and financial incentives
In field studies, advisory ISA systems are sometimes coupled with economic incentives to not speed. Researchers who conducted the first naturalistic driving study of ISAs in the U.S. concluded that drivers who received modest cash incentives for not speeding were more likely to abide by posted limits than drivers of vehicles with ISAs limited to providing speed alerts.
The study by researchers at NHTSA, Old Dominion University and Western Michigan University involved 50 drivers ages 24-39 with at least five years of driving experience. Participants drove study-provided vehicles fitted with an ISA for four weeks. Forty drivers received speed alerts. A subset of these were paid as much as $25 to drive within 4 mph of the speed limit in weeks 2-3. They lost money if they sped. A control group of 10 drivers didn't get alerts or cash.
Drivers in the incentive group reduced the percentage of time they drove 9 mph or more over the limit to less than 1 percent, compared with about 5 percent in the baseline period. Drivers in the control and warning-only groups traveled 9 mph or more over the speed limit as much as 9 percent of the time.
"The findings have implications for the use of intelligent speed adaptation systems in conjunction with insurance premiums to significantly improve traffic safety," the authors conclude. They note that a limitation of the study was its short duration.
In Denmark, researchers from Aalborg University and Copenhagen University evaluated an ISA combining speed advisories with insurance discounts and found that linking an ISA to incentives can reduce speeding. The greatest reductions were on roads with 80 kph (50 mph) limits. The calculated proportion of distance above the speed limit dropped from 13 percent in the baseline period to just below 4 percent in the study period. When drivers turned off the system, speeding relapsed to the baseline level. The 2007-09 field trial included 153 drivers ages 18-81 who drove their own vehicles fitted with an ISA.
Technologies to reduce speeding
Other technologies can help drivers stay within speed limits. Some GPS navigation systems and cellphone applications can provide real-time speed alerts. Roadside electronic signs that display vehicle speeds serve a similar function and have been shown to reduce speeding. Drivers also can use a vehicle's cruise control settings to avoid speeding.
Although not marketed as ISA systems, a few aftermarket in-vehicle monitoring devices that use GPS data to provide speed alerts are available in the U.S. Most are used by commercial fleets. Tiwi is one system available to consumers. The device provides verbal feedback to drivers who speed, don't buckle up or drive aggressively.
A 2009 Institute study found that equipping the cars teens drive with monitoring devices that provide real-time feedback can reduce their risks behind the wheel (see Status Report special issue: teenage drivers, May 7, 2009).
A number of U.S. insurers offer policyholders discounts for using various types of monitoring devices. Specifics differ in terms of what kinds of data get collected and whether a vehicle's location is tracked.