In its 2012 report on wrong-way driving, the NTSB concluded that driver alcohol impairment is the primary cause of wrong-way driving collisions and that the installation of interlocks on the vehicles of all convicted DWI offenders would reduce crashes caused by alcohol-impaired drivers (NTSB 2012c, wrong-way report). Numerous studies have shown that interlocks are effective in reducing recidivism among DWI offenders while the device is installed (Coben and Larkin 1999, 81–87; Tippetts and Voas 1998, 19–24; Willis, Lybrand, and Bellamy 2004; and Vezina 2002, 97–104). According to one estimate from the Insurance Institute for Highway Safety, if all drivers with at least one alcohol-impaired driving conviction within the previous 3 years had used zero-BAC interlocks, approximately 1,100 deaths, or about 10 percent of fatalities associated with alcohol-impaired drivers, could have been prevented in 1 year (Lund, McCartt, and Farmer 2007). As noted earlier, in MAP-21, Congress acknowledged the effectiveness of interlocks by providing funding incentives for states to implement laws requiring interlocks for all convicted DWI offenders. However, relatively few driver DWI arrests ultimately result in the installation of interlocks. In 2011, more than 1.2 million arrests were made for DWI (FBI 2013); yet, as of 2012, fewer than 280,000 interlocks were in use in the United States (Roth 2012).
Given the effectiveness of interlocks in reducing the likelihood that offenders will drive impaired, in its 2012 report on wrong-way driving, the NTSB made the following recommendation to the 33 states that do not mandate interlocks for all DWI offenders, the Commonwealth of Puerto Rico, and the District of Columbia:
Enact laws to require the use of alcohol ignition interlock devices for all individuals convicted of DWI offenses.
Aside from the lack of a universal mandate for interlock use among all convicted DWI offenders, one of the most significant challenges to the potential success of interlocks is the low rate of compliance38 among those offenders required to use them (DeYoung, Tashima, and Masten 2004). For example, one recent study found that within the subset of offenders who were ordered by judges to install interlocks, only about 24 percent ultimately did so (McCartt and others 2013, 215–29). In many states, offenders may avoid installing interlocks by stating that they will not drive during their license suspension period or by claiming that they do not own a vehicle.
Two NHTSA-sponsored reports provide suggested best practices for establishing and improving interlock programs (Sprattler 2009; Marques and Voas 2010). To improve offender compliance and program success, the reports advocated the following practices:
• Present the interlock as an alternative to a more restrictive penalty, such as house arrest or transdermal monitoring;39
• Provide financial assistance to individuals who cannot afford interlocks using fees from other offenders, arrangements with interlock providers, or alcohol tax revenues;
• Document interlock status on driver’s licenses so the information will be available to law enforcement officers during traffic stops;
• Establish a protocol for interlock-equipped vehicle usage; for example, track odometer readings or the number of BAC tests per month to ensure that the equipped vehicle is being used;
• Penalize drivers who are caught using non-interlocked vehicles with sanctions that are equal to or greater than those associated with driving-after-suspension/revocation charges;
• Establish an offender-monitoring program, with preestablished consequences for skipped or failed tests; and
• Set criteria for interlock removal based on a period of alcohol-free driving.
Some states have adopted some of these strategies to varying degrees. For example, Sprattler (2009) reported that 13 states and the District of Columbia had established indigent funds for offenders who could not afford interlocks. Marques and Voas (2010) reported that five states have provisions for extending interlock periods in response to repeated BAC lockouts, and since 2011, DWI offenders in Washington State may not reinstate their driver’s licenses until their installed interlocks are violation-free for not less than the last 4 months of their suspension period.
Additionally, studies that have tracked the implementation of some of the above-listed practices have documented improvements in interlock compliance. For example, a pilot program in one New Mexico county found that mandating house arrest as an alternate sanction to interlock installation led to 70 percent installation rates, compared to 17 percent rates in counties that did not adopt the house-arrest alternative (Roth, Marques, and Voas 2009, 437–41). Another study, conducted in Maryland, found that close monitoring of DWI offenders with installed interlocks resulted in significantly fewer attempts to start the vehicle by drivers with a positive BAC compared to offenders in a traditionally monitored control group (Zador and others 2011, 1960–67).
Existing NHTSA publications provide numerous potentially useful suggestions for states that are developing interlock programs; however, the NTSB is concerned that in the absence of more explicit information about which program elements lead to increased compliance, state interlock programs may suffer from low compliance rates and will not achieve their potential.
NHTSA’s Uniform Procedures for State Highway Safety Grant Programs (78 Federal Register [FR] 4986, 2013) have established few criteria for states to meet to obtain grant funding for their interlock programs. For example, states with a minimum interlock period as short as 30 days’ duration may still be eligible for grant funding, and no compliance goals or program elements are required to obtain funding. Because NHTSA has the duty to distribute federal grant funds in such a way as to support the establishment of state interlock programs, it has the opportunity to foster the development of highly successful state programs. The NTSB concludes that states would increase the effectiveness of interlock programs by employing those practices that have been shown to increase interlock compliance. Therefore, the NTSB recommends that NHTSA develop and disseminate to the states best practices for increasing interlock installation and compliance that are based on recent NHTSA research. To encourage states to implement these best practices, the NTSB further recommends that NHTSA create incentives for states to adopt the interlock best practices developed in response to Safety Recommendation H-13-02 (above). This recommendation is consistent with the comments the NTSB made to NHTSA concerning state interlock programs on April 24, 2013, in response to the Interim Final Rule on Uniform Procedures for State Highway Safety Grant Programs. (See 78 FR 15, published January 23, 2013.)
From the safety report Reaching Zero: Actions to Eliminate Alcohol Impaired Driving (NTSB/SR-13/01, adopted May 13, 2013, notation 8482): Additionally, because it continues to believe in the necessity of all-offender interlock laws, the NTSB reiterates Safety Recommendation H-12-4540 from its wrong-way driving report (NTSB 2012c), which calls on the 33 states that do not mandate the use of interlocks for all DWI offenders, the Commonwealth of Puerto Rico, and the District of Columbia to enact laws to require the use of interlock devices for all individuals convicted of DWI offenses.
Although interlocks traditionally have been used as a means of sanction for DWI offenders, they are increasingly being employed by others who recognize their benefits. For example, in Finland, Sweden, and France, interlocks are required on school buses, and in some European countries, commercial transport operators have installed them voluntarily (Daoud 2012). Several highway vehicle manufacturers have developed interlock systems (Griemel 2009 and Jurnecka 2007), and one manufacturer currently offers a wireless interlock system as an optional accessory for its passenger vehicles (Volvo 2013). Additionally, NHTSA is sponsoring research to examine the feasibility of an interlock program for teenage drivers. The NTSB supports this research and similar efforts to encourage voluntary use of interlocks, especially by high-risk drivers, such as teenage drivers and drivers with alcohol use problems, and by drivers whose impairment could result in particularly high numbers of deaths and injuries, such as commercial drivers.
Researchers and automobile manufacturers recognize that, to be acceptable to the broader driving public and encourage voluntary use, in-vehicle alcohol detection technologies must be unobtrusive, valid, reliable, and durable; must require only minimal maintenance; and must not interfere with the driving task (Ferguson and others 2009). In February 2008, a group of motor vehicle manufacturers affiliated with ACTS entered into a 5-year cooperative agreement with NHTSA to explore the feasibility, potential benefits, and public policy challenges associated with widespread use of in-vehicle technology for preventing alcohol-impaired driving. A promising technology, DADSS, is being developed under this agreement.
The DADSS program has resulted in two working prototypes that allow for the passive measurement of driver BAC. One system is touch-based and uses tissue spectroscopy to estimate driver BAC from the skin’s infrared light absorption; the other system uses multiple sensors inside the vehicle to estimate BAC through the driver’s exhaled breath. By mid-2013, the technologies are expected to be installed in demonstration vehicles for use in continued research and evaluation. For this program to be successful, it must not only address the myriad technical and engineering challenges posed by system development but also issues of usability, driver education, and public acceptance. In its 2012 report on wrong-way driving, the NTSB concluded that the DADSS program is working to solve both technical and practical challenges to make it an acceptable detection system for widespread implementation in the US vehicle fleet. In its Safety Recommendations H-12-43 and -48 from this report, the NTSB recommended that NHTSA and ACTS work together to accelerate widespread implementation of DADSS technology by (1) defining usability testing that will guide driver interface design and (2) implementing a communication program that will direct driver education and promote public acceptance.41
Because the NTSB continues to see a need for addressing the usability and public acceptance of the DADSS technology, it reiterates Safety Recommendations H-12-43 and -48.