How to turn part-time belt users into full-time users is an issue that has dogged policymakers for many years. Even though belt use is at a record 86 percent, more than half of the people who die in passenger vehicle crashes each year are unbelted. Last year's passage of the federal highway reauthorization bill opens the door wider for technological solutions to the problem. Among in-vehicle technologies to encourage belt use, results of a new Institute survey show that most motorists support enhanced belt reminders that are more persistent and intense than most U.S. vehicles have now, but belt interlocks still would be a hard sell.
Part-time belt users say these belt reminder strategies would...
Driver acceptance is crucial because early attempts to use in-vehicle technology to boost belt use backfired. In the early 1970s when belt use was very low, the National Highway Traffic Safety Administration (NHTSA) began requiring auditory and visual reminders in new vehicles to activate for at least a minute if front-seat occupants were unbuckled when a vehicle was started. This approach was followed by a 1973 mandate that all new cars that didn't have airbags or other passive restraints — and few did — be equipped with a belt interlock that prevented starting a car if the front-seat occupants were unbelted.
Public reaction to the interlocks was so negative that in 1974 Congress eliminated the standard and banned NHTSA from requiring belt interlocks or even allowing automakers to use them to meet federal safety standards. Congress also restricted the standard for belt reminders, specifying that NHTSA could only require auditory belt reminders with warning chimes or buzzers lasting 8 seconds or less.
Automakers were free to voluntarily use reminders with more persistent warnings, but few did so until recently. Ford was first to equip vehicles with enhanced reminders, beginning with some 2000 models (see "Some of us need a reminder," March 27, 2004). Today, most new vehicles sold in the United States have enhanced reminders for the driver and front passenger that exceed federal requirements. Among 2012 models, 91 percent had enhanced belt reminder systems for the driver, while 77 percent had them for right-front passengers.
Institute studies have shown that driver belt use is higher and fatality rates are lower in vehicles with enhanced belt reminders than in vehicles without them (see "Safety belt reminder system in late-model Fords boosts buckle-up rate," Feb. 9, 2002; "Belt reminders in Hondas are persuading motorists to buckle up," June 13, 2006; and "Effective belt reminders don't need to be relentless," March 6, 2012). The European New Car Assessment Programme (Euro NCAP) awards ratings points to vehicles with what it calls intelligent belt reminders. The main criteria are visual and auditory warnings that last for at least 90 seconds, either continuously or intermittently.
For example, under Euro NCAP rules, if a driver is unbelted and the car reaches a set speed, a light might flash and a chime might sound for 15 seconds every 30 seconds. The cycle would repeat at least six times unless the driver buckles up, so the warning would be present for the first three minutes of the trip. In contrast, many enhanced reminders in U.S. vehicles quit earlier, so drivers might ignore them altogether.
MAP-21, the 2012 highway reauthorization law, allows NHTSA to strengthen minimum requirements for belt reminders. The agency also can permit but not require automakers to use belt interlocks to comply with some regulations (see "LATCH, belt reminders get lift," Sept. 20, 2012).
"MAP-21 provides an opening for NHTSA to revisit technologies to increase belt use," says Anne McCartt, Institute senior vice president for research and an author of the new study. "Click It or Ticket publicity and enforcement campaigns and state primary belt use laws have sharply raised belt use since the 1970s and saved thousands of lives, but the success has plateaued in recent years. Studies show that enhanced belt reminders encourage people to buckle up. Our findings should help NHTSA and automakers sort out the most promising technologies that drivers would accept."
A good starting point would be to adopt European-style belt reminders. European research shows that belt use in vehicles with reminders meeting Euro NCAP requirements is about 12 percentage points higher than belt use in vehicles without them. Observed driver belt use is about 95 percent in vehicles with these European-style reminders. Among models sold in the U.S. with enhanced reminders, only about a third would meet Euro NCAP requirements, the Institute estimates.
To understand motorists' motivations and attitudes about buckling up and what they think about various types of belt reminders and interlocks, Institute researchers surveyed by telephone 1,218 drivers and passengers about their belt use. Ninety-one percent said they always use belts, 8 percent said they use belts but not on every trip, and 1 percent said they never buckle up.
Belt reminders are intended to get part-time belt users into the habit of always using belts. In the study, more than half of part-time belt users said they would be more likely to buckle up with audible reminders that incorporate a buzzer, chime or voice alert, or with haptic reminders that provide a physical cue such as a seat vibration. Nearly 3 times as many part-time belt users said they would be more likely to buckle up in response to an enhanced reminder that continues indefinitely or grows more intense the longer a person is unbelted as compared with a basic reminder that stops after a few seconds. Few vehicles in the U.S. have reminders like these. About half of all part-time users said this type of reminder would be acceptable.
Researchers asked everyone in the study their views of various types of belt interlocks. These include an ignition interlock that prevents the vehicle from starting until the driver is buckled, a speed interlock that limits vehicle speed to 15 mph, a transmission interlock that prevents the vehicle from being placed in gear, an entertainment system interlock to prevent use of the radio or other entertainment and communication systems, and resistance in the accelerator pedal if drivers don't use belts.
When asked about belt interlocks, 70 percent of part-time belt users said that belt ignition interlocks would make them more likely to buckle up. However, that doesn't mean that they would want them in their own vehicles. Just a third of part-time belt users said an accelerator interlock, entertainment interlock, speed interlock or ignition interlock would be acceptable in their vehicles.
Fewer than half of all full-time belt users said they would support using ignition interlocks to increase driver belt use. As for less-intrusive interlocks that intervene after the car starts, 53 percent of full-time belt users said they'd support speed interlocks or transmission interlocks, while 48 percent said they'd support an entertainment system interlock.
"Even though most people we surveyed buckle up, requiring belt interlocks is not popular," McCartt says. "For now, enhanced reminder systems are more acceptable, and in the public's view, almost as effective if persistent enough."