alcohol interlock curriculum

1. Alcohol Interlock
Curriculum:
Technology
Summary

2. 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

3. 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.

4. Technology

5. 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.

6. How does it work?
BAC = 0 Ignition
BAC <= 0.02 Warn
BAC > 0.02 Interlock
Running
Retest

7. 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.

8. Sensor technology
There are three different types of
sensors that may be used in alcohol
interlock devices:
• Semiconductor sensors
• Electrochemical sensors (fuel cells)
• Infrared sensors

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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

16. Device features
Language and visual display
BrAC threshold (pre-set limit)
Lock-out time
Stall protection time
Pull over notice
Recall notice
Breath volume

17. 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.

18. 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.

19. 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

20. 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.

21. 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.

22. 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).

23. 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.

24. 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).

25. Future technological advances
 The 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.

26. Future technological advances
 There 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.

27. 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.

28. 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