2017-05-26 Fri

Toronto Police

Strangier and strangier! Now we have a cop standing on the corner of Grenville and Yonge.

For the past few days we have had a lone cop standing on the corner.

This is an unusual sight in Toronto. Cops do not walk the beat, they cruse by quickly in their cruisers.

Toronto Cops do not hang around to learn about the neighbourhood from neighbours.

Toronto Cops often hang around to oversee the capable and competent graduate engineers who rotate those stop-go signs, but we have no stop-go traffic on Grenville right now.

Why am I so suspicious of Toronto Cops standing around, rather than cruising in their protective shells?

Clear Thinking

I am convinced that Jim Kenzie is off-track on this one.

Yet another plea to raise the Speed Limits.

The argument against raising the speed limits is based on a universal formula developed by Sir Isaac Newton hundreds of years ago.

Distance traveled (under acceleration or deceleration) is proportional to the SQUARE of the time, and the time is of course, the time it takes to bring the car to a stop, and THAT time is proportional to the initial Velocity.

In short, Stopping Distance is proportional to the square of the velocity.

An example: I am travelling at 100KM/hr, you are doing 120Km/hr. Your velocity is 1.2 times my velocity. You will need 1.44 times the distance to come to a stop.

If we consider “driving” to mean “collision-free driving”, then we ought to find out how much space each car needs.

Assuming a Vehicle Length of twelve feet, then each car needs twelve feet of space, even when the car is stationary.

Assuming a Driver Reaction time of 1.2 seconds, then we must add the distance the car will travel in 1.2 seconds before the driver’s foot gets to the brake pedal. That distance will be proportional to the velocity. Not the square of the velocity, just the velocity. At 88 feet per second, you will travel over a hundred feet before your foot reaches the brake pedal. Eighty-eight feet per second is sixty miles per hour or one hundred kilometres per hour.

Then we must add in the braking distance. You can get figures for braking acceleration (also known as deceleration) from any car dealer.

Add those three distances together and you have the space required for a car being driven.

Plot the distance required at each velocity, starting from zero and going up in increments of, say, ten kilometres per hour. You don’t need calculus, trigonometry, geometry or algebra for this; just plain simple arithmetic using addition, multiplication and, perhaps, division.

You will find that the space required for a twelve-foot vehicle is at a minimum at around 35Km/hr. Further inspection (imagine you are watching a stream of traffic through a narrow gap in a paling fence) shows that if we want to move the most people in the shortest time (that is, get everyone home to supper safely as well as quickly) the optimum speed (for cars, remember) is about 35Km/hour.

Now, if the lane is practically empty, cars can go faster, using more space, because there are so few cars on the road, but when the roads are congested (“hello North America!”), its good old 35Km/hr that delivers the goods.

Note too that longer vehicles (coaches and buses, tractor-trailers) can travel slightly faster and still be safe; that’s the impact of the longer length in the formula.

None the less, increasing the speed limits fro 100 to 120 is a bad move.

Oh yes. Something else that arose out of Sir Isaac Newton hundreds of years ago: Energy is proportional to the SQUARE of velocity, so when I am driving at 100 and you are doing 120, there is 1.44 times as much energy to be absorbed by your body when a collision occurs.

Just thought you’d like to know.