Technology

Questions & Answers

1a)	How does the alcohol interlock work and how is it installed?
1b)	What technologies are used in alcohol interlocks to detect alcohol in breath samples?
2)	How accurate are alcohol interlocks in detecting alcohol?
3)	Are there technical standards established for alcohol interlocks?
4a)	How does mouth alcohol affect the alcohol interlock device?
4b)	How do temperature and altitude (elevation) affect the performance of the alcohol interlock?
4c)	What is the expected warm-up time for an alcohol interlock?
5a)	What programmable features are provided with the alcohol interlock?
5b)	Who is responsible for programming the alcohol interlock device?
6)	Which anti-circumvention features are included with the alcohol interlock?
7)	What is a running retest?
8)	What is the emergency override feature, and how does it work?
9)	What types of alcohol interlock technology are being considered for future use?

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1a) How does the alcohol interlock work and how is it installed?

• The alcohol interlock device is connected to the starter or ignition, or other on-board computer system of a vehicle. To start the vehicle the driver must provide a breath sample with an alcohol concentration below the pre-set limit (usually corresponding to blood alcohol concentration of .02%). If an alcohol concentration above this limit is detected the vehicle will not start.
• The alcohol interlock disrupts the power supply to the starter creating an open circuit between the vehicle’s ignition switch and the starter system. Power cannot reach the starter system unless a breath sample with a sufficiently low or no alcohol concentration has been provided.
• Once this condition has been satisfied, the alcohol interlock closes the open circuit and permits a power supply to be released to the starter system which will provide power to the vehicle when the ignition is turned to the start position. The driver is then obliged to provide repeated breath samples at specific intervals while the vehicle is in use to ensure the driver remains sober.
• It is important to note that the alcohol interlock is connected to the starter system of a vehicle and not to the engine, and therefore, will not affect a running engine.
• The installation of the alcohol interlock on most vehicles is relatively simple and takes between 45 minutes and 2 hours depending on the sophistication of the vehicle and the experience of the installer. Generally, most installations require about 45 minutes and should always be completed by a licenced, professional installer. During the installation process, the offender also receives information about the alcohol interlock device and learns how to blow into the device to provide a breath sample.

1b) What technologies are used in alcohol interlocks to detect alcohol in breath samples?

• There are three types of sensors that are used in alcohol interlock devices: semiconductor, electrochemical, and infrared.
• Semiconductor technology is less expensive compared to both electrochemical sensor and infrared technology, but this sensor is not alcohol-specific (i.e., a positive alcohol reading can be triggered by other substances such as perfume or cigarette smoke), resulting in frequent false positive tests so the driver is wrongly locked out from starting the vehicle. These devices also require maintenance more often (every 30 days) to maintain the accuracy of the alcohol interlock.
• Electrochemical sensors address the two shortcomings of semiconductor sensors: they ensure that positive alcohol readings are the result of alcohol in the breath of drivers (alcohol-specific) and require less frequent calibration (e.g., once every several months). While electrochemical sensor technology is slightly more expensive than semiconductor technology, it is much more accurate and reliable.
• Infrared technology has greater long term stability compared to electrochemical sensor technology and semiconductor technology and is commonly used for evidential breath testing. However, this technology is impractical for alcohol interlock devices due to its large size. Moreover, this technology is quite expensive and there is a high level of difficulty associated with achieving specificity and accuracy at low breath alcohol concentration levels.

2) How accurate are alcohol interlocks in detecting alcohol?

• Alcohol interlocks containing an electrochemical sensor are accurate in detecting alcohol consumption 99% of the time; semiconductor sensor devices have a much lower accuracy rate and detect “alcohol” when it is not present.
• According to 1992 NHTSA technical standards (currently under revision) these devices must meet specific accuracy requirements. The NHTSA standards specify that vehicles equipped with alcohol interlocks with a .02% pre-set limit must be prevented from starting under extreme conditions 98% of the time when a breath sample registers at least .065% (Beirness 2001).
• It must be noted that the primary purpose of the alcohol interlock is to prevent an impaired driver from operating a motor vehicle (to accurately detect alcohol), and to prevent circumvention and tampering. The objective of the device is not to provide drivers with a precise measurement of their breath alcohol content (although the accuracy of the breath alcohol measurement with an electrochemical sensor is close to an evidential level).

3) Are there technical standards established for alcohol interlocks?

• Technical standards established for alcohol interlocks vary across jurisdictions and according to the intended purpose of the device (i.e., monitoring impaired driving offenders vs. monitoring commercial drivers). 
• In North America, alcohol interlocks are primarily installed in private vehicles with the intention of monitoring impaired driving offenders. In the European Union (EU), alcohol interlocks have also been installed in commercial vehicles (e.g., buses, taxis, heavy trucks).
• Technical standards currently exist in the United States, Canada, the EU, and Australia. Efforts to update the U.S. technical standard for alcohol interlocks are almost completed and the new standard is expected to be released in late 2008.
• A revised technical standard has recently been implemented in Canada, and in 2007, the EU updated their technical standard which is the most stringent standard available. These initiatives to update technical standards reflect technological advances and design improvements. The goal of a technical standard is to ensure a uniform standard for devices, consistent quality, and efficacy in these 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 can be inconsistent across jurisdictions.

4a) How does mouth alcohol affect the alcohol interlock device?

• If alcohol from recent consumption of food, drink, mouth spray, or medicine is present in the mouth or throat at the time that a breath sample is being delivered, an elevated alcohol concentration will be detected and the alcohol interlock will prevent the engine of the vehicle from starting. As a result, drivers are advised not to consume anything containing alcohol for 5 minutes prior to the breath test.
• Residual mouth alcohol will dissipate within a few minutes of consumption as it is taken up by saliva or absorbed into the body.
• If taking medication, users should note whether or not the medication contains alcohol because if the breath sample registers a BrAC above the pre-set limit the alcohol interlock will prevent the vehicle from starting and a breath test violation will be recorded.

4b) How do temperature and altitude (elevation) affect the performance of the alcohol interlock?

• The National Highway Traffic Safety Administration (NHTSA) recognizes that some jurisdictions are subject to extreme temperatures and other conditions.
• Generally, extreme temperatures and altitude levels have nominal effects on alcohol interlocks. These devices are designed to withstand adverse effects of temperature and elevation similar to all other technologies that are a regular part of vehicle design.
• 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 metres) (Burger 2001 cited in Bax et al. 2001).
• Extreme temperatures and altitude will not affect the functioning of an alcohol interlock, with the exception of a 5 minute warm-up time in extreme cold temperatures.

4c) What is the expected warm-up time for an alcohol interlock?

• The duration of the warm-up time typically spans from a few seconds at moderate and high temperatures to a few minutes at very low temperatures.
• While warm-up time is an inherent feature of the alcohol interlock (similar to a photocopier), it nonetheless can cause inconvenience and frustration for drivers in extreme temperatures (Beirness et al. 2007).
• Technological advances have reduced the warm-up period. For example, the wireless alcohol interlock allows drivers to provide a breath sample up to five minutes before entering the vehicle. The handset of the device would be with the driver and not in the vehicle, and thus, would be warm. This option is particularly useful in extremely cold climates. Wireless communication occurs between a handset and a control unit that are up to 50 metres apart.
• However, the wireless device does increase the opportunity for someone other than the driver to deliver the breath sample. For this reason, the European Standard for these devices (EN 50436-2) requires that wireless communication occur between the handset and the control unit within 30 seconds of the analysis of the breath sample.

5a) What programmable features are provided with the alcohol interlock?

• Devices have a wide range of programmable features which allows manufacturers to customize the devices to meet requirements in different jurisdictions. Some of the features that are available with most alcohol interlock devices include: language and visual display, pre-set limit or BrAC threshold, lock-out time, stall protection time, pull over notice, recall notice, and breath volume.

5b) Who is responsible for programming the alcohol interlock device?

• In some states, the Department of Motor Vehicles (DMV or its equivalent) certifies the alcohol interlock and ensures specific features have been programmed by the manufacturer and are operational as required by state regulations. Once the alcohol interlock is certified according to state regulations, the manufacturers are responsible to program all devices for use in the state accordingly. Some DMVs may also conduct routine and random inspections of service centres to ensure quality control of alcohol interlock devices and that features are operational.
• In other states, service providers may be responsible for programming various features on the alcohol interlock device before it is installed. In these instances, it is important that the state closely monitor service providers to ensure that all devices are programmed to meet the necessary requirements.

6) Which anti-circumvention features are included with the alcohol interlock?

• Earlier versions of alcohol interlocks could be easily bypassed due to their limited anti-circumvention technology. For example, alcohol interlocks were not equipped with features that could detect and/or prevent a bystander from providing a breath sample on behalf of a driver, or detect the substitution of stored air samples (e.g., in a balloon).
• Modern alcohol interlock devices have greatly reduced opportunities for circumvention and tampering with the device. Technical standards and jurisdictions require several sophisticated and effective anti-circumvention features (National Highway Traffic Safety Administration 1992).
• Anti-circumvention features include sealed wiring, temperature and pressure gauges, a data recording device, and systems that reduce the likelihood of someone other than the driver providing a breath sample, or providing a non-human sample.

7) What is a running retest?

• A running retest is a random, repeated breath test that a driver must continue to provide once the vehicle has been successfully started.
• The purpose of the running retest is to prevent the driver from drinking once the vehicle is idling or in motion, and to detect escalating BrAC levels in the driver once the vehicle has been started. Such increases in BrAC can result either from drinking while driving or simply drinking immediately prior to driving, resulting in ascending blood alcohol content as the alcohol metabolizes over time.
• There has been some concern raised regarding the safety of performing a running retest while the vehicle is in motion. However, the running retest prompt provides the driver with sufficient time to pull over at the side of the road in a safe location, or wait until stopped at a red light, to perform the retest. At no point will the alcohol interlock shut off the engine and create a traffic hazard (Beirness 2001).

8) What is the emergency override feature, and how does it work?

• The emergency override is a feature available on some alcohol interlocks. Some jurisdictions may require this feature to be activated while others do not. The feature essentially permits the driver to override the alcohol interlock system in the event of an emergency -- i.e., it allows the driver to avoid providing a breath sample before starting the vehicle, usually one time only.
• The availability of the override feature is contingent on approval from the program administrator. For instance, jurisdictions such as Florida and Quebec permit the override feature, whereas jurisdictions such as Pennsylvania and Ontario do not (Robertson et al. 2006).
• This feature allows the vehicle to be used in emergency situations during which the use of the vehicle is necessary or to allow another person not familiar with the device to start the vehicle (Beirness and Boase 2007).
• Some concerns have been raised regarding the potential for this feature to allow an intoxicated individual to operate a vehicle and the liability this may create, and the potential abuse of this feature by offenders. For these reasons, it is essential that the override feature be transparent, meaning that the data recorder continues to record relevant information (e.g., distance driven, length of time the vehicle was driven) once it has been activated in order to compare the vehicle use with the explanation provided by the driver.
• To prevent misuse of this feature, program administrators can require servicing following each use of the feature, or require servicing within a restricted time period.

9) What types of alcohol interlock technology are being considered for future use?

• In recent years, there has been some discussion regarding the installation of alcohol interlocks as a standard feature on all motor vehicles, and some vehicle manufacturers are pursuing research in this area.
• The current technology is designed primarily for offenders and professional applications and will likely be less appropriate for private citizens. For this reason, efforts are underway to develop unobtrusive methods for detecting alcohol consumption by drivers. 
• To increase acceptance of and compliance with the use of alcohol interlocks in all vehicles, several criteria must be met: devices must be fast, accurate, reliable, and repeatable, and cannot impede or interfere with a vehicle from starting or being started if the driver is not alcohol impaired. They must also be functional across a wide range of driving and environmental conditions, require little or no maintenance, and be tamper/circumvention resistant.
• A few existing technologies are currently being explored and tested for viability for future alcohol interlock applications. These include infrared tissue spectroscopy, vapour detection, transdermal alcohol monitoring, vehicle-based impairment detection, and ocular measures. It should be noted however, that this technology is still several years away from being fully developed.