Driving a physics lesson in time and distance
By Steve Wallace, Times Colonist, August 24th, 2012
The vast majority of new drivers I have taught genuinely believed they could do virtually every driving manoeuvre quicker than they actually could.
When I ask a student to go from 0 to 80 kilometres per hour as fast as they can, they ridiculously underestimate the time and space needed to complete the task.
Most new drivers will say it takes far less time than needed, and choose a point down the road by which the 80 km/h speed should be reached that is much closer than the distance actually required.
When they’re in the act of doing something, time always seems to pass much more quickly. Getting new drivers to understand this concept is difficult at best and impossible at worst, unless it’s actively demonstrated.
When I ask new driving students how many hydro poles it takes to pass a car on the highway, they usually think it will take three or four pole lengths and six seconds to pass. It actually takes them at least 10 to 12 pole lengths and a minimum of 12 seconds for a safe pass. This kind of revelation must be actively experienced by a new driver to be fully appreciated. To do is to learn, and to learn is to do.
Even the basic act of turning is difficult to estimate for a new driver. Most will say it takes three to four seconds to complete a right turn at an ordinary intersection. The actual time necessary is about twice that.
This is a drill that I have only seen properly completed by one in a thousand such drivers. After an extended high-speed highway cruising session, I will ask the student to go school-zone speed as I cover up the speedometer.
They consistently travel at speeds of 50 km/h or higher, and sincerely believe they are at 30 km/h. When confronted with the actual speed reading, they are incredulous.
I have had several student drivers, while doing this drill, claim there must be something wrong with the speedometer. It’s not just learners, either. Most drivers have a hard time accurately judging the lower school-zone speed once they are accustomed to the high speed of highway driving.
After experiencing the true 30 km/h speed, one student announced that he could run faster than that. I called his bluff.
After a short city block, the boastful runner yelled at me to stop and admitted he got the point. What seemed to him painfully slow was actually much faster.
When new drivers are asked to estimate stopping distance, the exercise becomes both educational and entertaining. They always think they can stop faster than they really can. Estimating stopping distance is difficult for experienced drivers, let alone learners. Again, only one in a thousand new drivers I have taught (usually physics students) understands the relationship between speed and braking distance.
When speed doubles, stopping distance increases by four times, not two. Demonstrating this principle is probably the most important thing a new driver must experience. Steering rather than braking to avoid hazardous situations quickly becomes a priority.
In all of the above circumstances, drivers make the elementary mistake of thinking driving actions are faster than they actually are. We would all do well to allow more time and space for every driving manoeuvre. (The teaching methods described are always done in a relatively controlled environment, with no inconvenience to the driving public).
Steve Wallace is the owner of Wallace Driving School on Vancouver Island and in the Central Interior of B.C. He is the former Canadian vice-president of the Driving School Association of the Americas and a certified teacher with a degree from the University of Manitoba.