Alcohol Interlock Curriculum:TechnologySummary

Technology This section contains the following information:

• How the alcohol interlock device works• Installation• Sensor technologies• Accuracy• Technical standards and certification• How mouth alcohol affects the interlock• Environmental influences• Features and programming capabilities• Tampering and circumvention• Running re-test• Emergency override options• Future technological advances• Conclusions

Introduction An alcohol interlock is a

breath-testing device attached to a car’s starter.

It prevents the car from being started when a pre-set level of alcohol (usually .02) is detected in the breath sample presumably provided by the driver of the vehicle.

Technology

How does it work? The breath testing device is attached to the vehicle starter, or

other on-board computer system.

The device “interrupts” the flow of power to the starter using an open relay switch.

If the level of alcohol detected in the breath sample is below a pre-set limit (usually .02), the relay switch is closed allowing power to flow to start the vehicle.

Repeated breath tests are required while the vehicle is in use to ensure the driver remains sober after starting the vehicle.

The alcohol interlock is not connected to the engine and therefore, cannot affect a running engine.

How does it work?BAC = 0 Ignition

BAC <= 0.02 Warn

BAC > 0.02 Interlock

Running Retest

Installation On average, the installation of the interlock device

takes approximately 45 minutes. It can take up to two hours depending on the

experience of the installer and sophistication of the vehicle electronics.

A wiring harness may be needed to facilitate installation on high-end vehicles.

During the installation the offender receives information about the device and learns how to blow into it to provide a breath sample.

Offenders may also receive a certificate to submit to the program authority as proof of installation.

Sensor technologyThere are three different types of

sensors that may be used in alcohol interlock devices:• Semiconductor sensors• Electrochemical sensors (fuel cells)• Infrared sensors

Sensor technology Fuel cell sensors are most commonly used in

interlock devices. These sensors are ethyl alcohol-specific and

require less frequent calibration. Fuel cell technology is more accurate and

reliable than semiconductor technology. Many jurisdictions no longer permit the use of

semiconductor devices.

Accuracy Alcohol interlocks containing an electrochemical sensor are

accurate in detecting alcohol consumption 99% of the time.

Alcohol that is detected can be in the form of beverage alcohol that is consumed, or alcohol in medications or other ingested products (e.g., cough syrup, mouth wash).

The NHTSA specifications state that the alcohol interlock device must prevent the driver from starting the vehicle (even in extreme heat or cold conditions) 98% of the time when the BrAC is .065 or greater (Beirness 2001).

The specifications emphasize prevention of circumvention and tampering rather than the precise measurement of alcohol.

Technical standards Technical standards to specify the performance requirements

of interlock devices have been implemented in several countries (e.g., United States, Canada, European Union, and Australia).

The goal of a technical standard is to ensure a uniform standard for devices, consistent quality, and efficacy in these devices.

Most jurisdictions have only one standard for offender-based applications. A few jurisdictions have additional standards for other classes of drivers (e.g., commercial drivers).

The European standards are the most contemporary, comprehensive, rigorous, and high-quality standard available at this time.

Certification of devices Many jurisdictions in the U.S. require that a device is

certified by the state to ensure that it meets necessary technical requirements and is approved for use.

Once the device/manufacturer has been certified by the state, the device is ‘approved’ and can be made available for use.

Certification tends to be inconsistent across jurisdictions as the agencies doing the device testing and certification vary.

Mouth alcohol Mouth alcohol is residual alcohol that is present in the

mouth or throat immediately following the consumption of food, drink, mouth spray, or medicine that contains alcohol.

Mouth alcohol can register on an interlock device as an

alcohol-positive breath sample and can prevent the engine of the vehicle from starting.

This is easily overcome by waiting a few minutes to allow residual alcohol to dissipate, similar to an evidential breath test.

Drivers are advised not to consume anything containing alcohol for five minutes prior to the breath test.

Environmental influences Generally, extreme temperatures and altitude have

nominal effects on alcohol interlocks.

Devices are designed to withstand adverse effects of temperature and elevation similar to other common vehicle design technologies.

Most interlocks can withstand temperatures ranging from -49 to +185 degrees Fahrenheit (-45 to +85 degrees Celsius) and altitudes of up to 11,482 feet (3,500 meters) (Burger 2001 cited in Bax et al. 2001).

Extreme temperatures and altitude will not affect the functioning of an interlock, with the exception of a five minute warm-up time.

Environmental influences The electrochemical sensor in an interlock device operates at

a high temperature.

For this reason, a brief warm-up period before the device can analyze a breath sample is essential (much like a photocopier).

Warm-up time typically spans a few minutes and is influenced by environmental and climatic variables. In extreme cold environments, a longer period of up to five minutes may be required.

Technological advances have significantly reduced the warm-up period. These include:• detachable handset• wireless device

Device featuresLanguage and visual displayBrAC threshold (pre-set limit)Lock-out timeStall protection timePull over noticeRecall noticeBreath volume

Device features New emerging features improve the ability of

authorities to monitor interlock offenders.

These features include:• GPS;• Real-time reporting;• Video streaming; and, • 911 notification.

They can be used as graduated sanctions for offenders who are consistently non-compliant.

Programming the device In many states, the Department of Motor Vehicles

(DMV) is responsible for certifying the alcohol interlock and ensuring that specific features have been programmed by the manufacturer. • Other departments that may be responsible for

certification are Department of Transportation and Department of Corrections.

In a few states, service providers are responsible for programming. This can result in inconsistent programming of features in some devices.

Tampering and circumvention There are several anti-circumvention features

available for alcohol interlocks including:• Sealed wiring• Connectors • Temperature and pressure gauges• Systems to reduce the likelihood of breath

samples from non-drivers• These include – breath pulse code, hum-tone

recognition, blow and suck method, and photo recognition.

• Data recorder

Tampering and circumvention The data recorder captures the date and time

of:• All initial breath tests and running re-tests;• Any attempts to start the vehicle; and, • Any attempts to tamper with or circumvent the

device.

It also records the following:• Breath sample violations;• Lock-outs resulting from positive BrAC readings;

and, • Activation of the emergency override feature.

Running re-test The running re-test feature ensures that a driver

remains sober while driving.

It requires random and repeated breath samples while the vehicle is in use. The first re-test generally occurs within 5-15 minutes after the vehicle has been started.

A breath sample above the pre-set limit will result in a warning for the driver to pull over and stop driving.

If drivers do not provide a sample or fail an alarm/horn will sound and lights will flash.

Running re-test At no point will the interlock shut off the engine and

create a traffic hazard (2001).

There has been some concern raised regarding the safety of performing the re-test while the vehicle is in motion.

Drivers have enough time to pull of the road or wait for a stop sign or red light to provide the breath sample.

Also, a study found that the mental workload associated with texting while driving was greater than performing a running re-test (Medeiros-Ward and Strayer 2011).

Emergency override The emergency override is a feature available on some

alcohol interlocks.

It allows the driver to avoid providing a breath sample before starting the vehicle one-time only.

The availability of the override feature is contingent on approval from the program administrator – i.e., some jurisdictions permit it while others do not.

There are ethical concerns associated with the non/use of this feature as it has the potential to create liability if abused.

Future technological advances In the future, alcohol interlocks may be a

standard feature on all vehicles.

In order to achieve general acceptance, this technology must be fast, accurate, reliable, and repeatable. • It must also be functional across a wide range

of driving and environmental conditions, require little or no maintenance, and be tamper/circumvention resistant (DADSS 2012).

Future technological advancesThe following technologies are currently

being developed by the DADSS project:• Infrared (tissue) spectroscopy

• Touch-based sensors• Offset spectroscopy (vehicle-based

impairment detection)• Breath-based sensors

This technology is still several years away from being fully developed.

Future technological advancesThere are also alternatives to the use of

alcohol detection devices in vehicles including transdermal and in-home monitoring.

These can be applied as a graduated sanction for consistently non-compliant offenders.

Conclusions An alcohol interlock requires a driver to perform a

breath test to start a vehicle, and provide repeated breath samples while the vehicle is in use.

Advances in alcohol interlock technology have overcome many of the limitations associated with earlier devices.

Technical standards and certification requirements govern the use of delivery of these devices across jurisdictions.

Devices can withstand many environmental influences and have a variety of programmable features.

Conclusions Devices possess a variety of features to prevent

tampering and circumvention.

A data recording device records all relevant vehicle activity.

The running re-test prevents drivers from consuming alcohol once the vehicle is in motion.

Use of the emergency override feature varies across jurisdictions.

Other alcohol detection technologies are being explored to gauge their potential for use in all vehicles. Nov. 28, 2012