Dead tired or dead drunk? Fatigue kills - The tests: booze vs snooze

We compiled a series of tests to compare drink-driving with driving while tired.

Our experiment, designed with the help of TRL chief scientist and research director Professor Andrew Parkes, sought to test the theory that an exhausted driver can be just as lethal as one who has an excess of alcohol in their system.

Our sleepy driver was former What Car? editor David Motton; group consumer editor Peter Lawton was the drunk driver.

Both went through the same tests on the simulator at TRL. More realistic than any games console, the simulator is a real Honda Civic wired up to a computer to examine the performance of both drivers.

A 3D landscape - projected onto screens in front, behind and on each side of the car - offered a 'real-life' view from the driver's seat.

The subjects started their test drive on a virtual motorway. The first task was to keep an even distance from the car in front as it accelerated or slowed down.

Once the lead car caught up with other vehicles, the drivers were free to interact normally with other traffic.

Next, the route reached a series of long bends, which drivers were asked to tackle at 60mph, keeping as close as possible to the centre of the lane.

Finally, to test reactions times, each driver was asked to flash his lights the moment a red bar appeared on the screen.

The first test was at 7pm; it was then repeated at 9pm, 11pm, 2am and 7am.