A school in Canada is using a weird 3D optical illusion of a young girl crossing the road to rein in rowdy drivers.

The image of a girl pursuing a ball is painted on the road and lengthened to make it seem three-dimensional, viewed from an approaching car.

Critics aver that the child's image could jolt the drivers into slamming on the brakes or swerve off the road if they don't realise the girl is just an illusion, reports the Daily Mail.

From afar it just looks like a marking but when the car is close to 30 metres, it appears to instantly rise up from the road.

When the driver is closer than 30 metres the image appears to sink back into the road. If a car is travelling at the speed limit for the road, 30 kmph, then he should be able to stop in time before he reaches the image.

Safety experts say the alarming image is designed to teach drivers to always be prepared for the unexpected.

The illusion is to be placed on the road outside the ecole Pauline Johnson Elementary School in West Vancouver in Canada and will be accompanied by a sign which reads: 'You're probably not expecting kids to run into the road.'

Area's council bosses say that the illusion will encourage drivers to drive defensively, as though a child could run out into the road at any moment. The image will be removed after a week.