REACCIONES BIOLOGICAS

EN 50436 specifies a performance standard for the alcohol interlock devices in order to guarantee that devices that apply to these standards and have received type approval function as intended.

However, this does not mean that no issues exist regarding the functioning of type approved alcohol interlock devices. The main technical issues identified in studies and from stakeholder consultations are described in this section. These include:

• installation and interference electrical vehicle systems; • warm up time;

• breath sampling; • running retests;

• sensitivity alcohol detection, false positives.

4.3.1 Installation and interference electrical vehicle systems

For installing an alcohol interlock into the vehicle it has to be connected to the electric circuits of the vehicle. According to EN 50436 the electrical properties of the vehicle (e.g. alternator, accessories, on-board circuitry, grounding, contact safety etc.) shall not be adversely affected by an alcohol interlock when installed according to the manufacturer’s instructions.

Technically, it was so far possible to install alcohol interlocks in all vehicles. However, the technology of vehicles develops more and more into electronically controlled vehicle systems using data bus communication. As a result, installation of alcohol interlocks becomes much more difficult and it is envisaged by CENELEC Working Group BTTF 116-2, that today’s conventional installation method will no longer be possible in the near future (Lagois, 2012).

In order to solve this problem, cooperation between the automotive industry and alcohol interlock manufacturers is required.

Draft document prEN 50436‐4 prepared by CENELEC Working Group BTTF 116-2, contains an effort to create a standard for the electrical connection between the alcohol interlock and the vehicle. The draft was put on hold because it was not accepted by car manufacturers. There is a need for renewed attention to this draft, e.g. as new hybrid vehicles now start to appear in the market without the option of installing alcohol interlocks.

4.3.2 Warm up time

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). In general the lower the temperature is, the longer the warm-up time gets. As such warm up times typically range from several seconds to several minutes at very low temperatures. Various studies (Burström, 2008; Trafi 2012, 2013) have identified warm up times as one of the largest problems experienced by drivers participating in alcohol interlock programmes. The waiting time results in costs to the user (Svensson Smith, Nilsson & Schönning, 2006). It is however unclear if, or to what extent, these problems could deter drivers in general and drink-driving offenders in particular, from participation in an alcohol interlock programme.

4.3.3 Breath sampling

According to EN 50436-1 and EN 50436-2 alcohol interlock devices used in respectively drink- driving offender programmes and general preventive programmes require a breath sample using a mouth piece.

The breath sample needs to fulfil certain requirements for volume, flow, exhalation time. Also alcohol interlock devices should be able to detect if breath samples are delivered directly by a person and not, for example by using pressurized artificial air or an indirect method, like breathing through a water bottle. Therefore alcohol interlock devices make use of some form of human recognition feature that the driver must provide when providing the breath sample. This can include making sound vibration, breath pulse codes or hum-tones when the driver is exhaling.

Research has shown that drivers can face difficulties mastering the correct exhalation technique. In a survey carried out by Trafi (2013) amongst drivers participating in a drink-driving offender programme, exhalation problems were the most frequently stated problem with the functionality of alcohol interlocks along with warm up time.

Almost 40 per cent (N=664) of drivers indicated to have problems with the exhalation technique, which could lead to unaccepted breath samples10. Although some drivers indicated that problems ceased after having mastered the exhaling technique, for other drivers the problems persisted. In particular respondents with asthma, pulmonary or vocal cord diseases or influenza found exhaling difficult.

Based on a manufacturer estimate and interlock log data analysis quoted in the same report, it was estimated that on average between 9 and 15 per cent of drivers’ exhalations were erroneous. The average percentage of exhalation errors decreased toward the end of the probationary period. This could indicate that in time drivers indeed master the required exhalation technique. At the same time it has also been noted that offenders often try to circumvent the interlock in the first few weeks by tampering with breath samples and attempting to disengage the device. Tampering rates decrease over time as offenders recognize the futility of trying to circumvent the technology (Beirness et al., 2007).

4.3.4 Running retests

Another feature related to breath sampling that has been mentioned in evaluation studies for causing problems is ‘running retest’ requirement.

Alcohol interlock devices that are used in drink-driving offender programmes require random, repeated breath tests (running retests) once a vehicle has been started successfully. For alcohol interlock for general preventive use this feature is optional.

Random retesting is to detect and deter drivers from drinking once the vehicle has been started and the engine is idling. As the driver must repeatedly provide alcohol-free breath samples, alcohol interlock device can detect a rising BAC level in drivers also after the vehicle has been started. Running retests also reduce the likelihood of a bystander providing a breath sample to start the vehicle on behalf of a driver.

If a driver fails to provide a running retest or register a BAC in excess of the pre-set limit, either an auditory or visual warning or activation of an alarm will occur to alert law enforcement. The event is registered in the data log and shortens the maintenance service intervals. The interlock does not have the ability to stop the vehicle once it is running for safety reasons.

Surveys conducted under participants in alcohol interlock offender programmes in several studies (e.g. DeYoung, 2002 and Trafi, 2013) pointed out various issues related to random retest:

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It should be noted that acceptance or rejection of the breath sample is independent of alcohol concentration, but relates to fulfilling the requirements for volume, flow, exhalation time and other considerations such as human recognition.

Amongst others, drivers thought exhalations were required too often and drivers did not always notice the request, or the device did not accept the exhalation. More importantly, concerns have been raised regarding the safety of performing a running retest while the vehicle is in motion.

Running retests are not designed to be done while the car is actually rolling. Interlocks give people a few minutes – enough time to pull over – to perform the retest. This is also strongly recommended by alcohol interlock manufacturers (Robertson et al., 2006). Nevertheless, most people take retests whilst driving (92% in the survey carried out by Trafi). In particular in heavy urban traffic, at

crossings and when the traffic was congested surveys found that some drivers felt distracted or unable to stop at the road side, leading to dangerous situations.

At the same time the majority of drivers do not experience dangerous situations due to the running retest requests. Also there is no known data on accidents levels that would indicate that retest could result in more accidents.

4.3.5 Sensitivity alcohol detection and false positives

Another technical issue frequently discussed with regards to alcohol interlocks is their accuracy and sensitivity of alcohol detection.

When properly calibrated alcohol interlocks type approved are accurate enough to determine the presence of alcohol and its concentration (see also next section). False positive readings for alcohol will therefore be kept to an acceptable minimum in accordance with the standard.

At the same time it is known that drivers could test positively for alcohol without the driver having drunk. This can be caused by the presence of ‘mouth alcohol’. 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. Residual mouth alcohol will dissipate within a few minutes of consumption as it is taken up by saliva or absorbed into the body. The breath test violation will be recorded however. This shortens the maintenance interval of the interlock device and might also lead to administrative or judicial sanctions.