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Cannabis Campaigners' Guide News Database result:
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UK: Hand-held device detects impaired drivers
Graham Lawton New Scientist
Wednesday 19 Nov 2003 A hand-held device designed to identify drivers impaired by drugs, alcohol or excessive tiredness, is being evaluated by the British police. The device is intended to deliver a quick yes or no verdict on whether a person is in a fit state to drive and works by assessing the driver's behaviour, rather than testing for particular substances. It is the first of its kind to be tested by police anywhere in the world. The "impairment detector" is still in the early stages of development, but the Police Scientific Development Branch (PSDB) in St Albans, Hertfordshire, is studying results from a prototype to decide whether to take the project further. If it gets the go-ahead, at least two years of testing will be needed before the detector is ready for the streets. "Early results are very promising," says Julia Boyle of the University of Surrey in Guildford, UK, who is leading the research on behalf of the PSDB and who revealed the results last week at a conference at Cranfield University. Twin test Boyle's prototype runs on a PDA. It provides two tests, which take about 10 minutes to complete, and assess whether a person is too impaired to drive (see Unfit to drive?" below). Her team tested the prototype at two music festivals this summer, where people who will admit to being impaired are relatively easy to find. With 170 volunteers, the researchers found a significant difference in performance between people who said they had not taken drugs and those who admitted to being under the influence. The main purpose of the device is to detect people who are unfit to drive because they have taken illicit drugs, Boyle says. This is a growing problem in the UK, where 18 per cent of road casualties in 2002 were found to have traces of drugs in their bodies, compared with just 3 per cent 10 years ago. The detector would deliver a verdict similar to the way a breathalyser indicates how much alcohol is in the blood, with positive, negative and a grey area between the two. Thresholds for these levels have yet to be set, says Boyle. Lingering traces As well as helping to screen people at the roadside, the test could help to solve some of the problems that arise from testing for traces of drugs in a driver's body. Cannabis, for example, lingers in the body long after its effects on behaviour have faded. This allows drivers found to have residues of the drug in their blood to argue in court that they were not impaired at the time of driving. And with so many illicit drugs in common use, it is hard to devise a test that could pick them all up. Performance enhancing drugs do not enable impaired drivers to beat the test, says Boyle. A spokesman for the UK home office says it is too early to comment on how such a device would be used or whether the results it produces would be admissible as evidence in court. UNFIT TO DRIVE? The prototype impairment detector runs two tests designed to assess three critical driving skills: motor control, ability to react to the unexpected, and concentration levels. In the first test, volunteers are asked to use a stylus to track an object moving across the screen of a PDA, while every so often another object pops up in the corner of the screen. When that happens, the volunteers are required to press a button while continuing to track the moving object. This test assesses the subject's ability to perform a motor control task while their attention is diverted by unexpected events. In the second task, road signs flash up on the screen every second. The driver has to respond to each of them, except a "target" sign that they have been told about at the start of the test. When the target flashes up they must not respond. This is known as a "sustained attention" task, and measures a person's ability to concentrate. The tests were chosen from a wider battery of tests developed at the University of Surrey, UK, to assess the effect of drugs and sleep deprivation on people's ability to drive safely. Graham Lawton
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