Friday, July 24, 2009

hit and run hurts five ottawa cyclists

Ottawa police say they have made an arrest after a minivan struck and seriously injured five cyclists. At least two of the cyclists are listed in critical condition.

D: by leaving the scene instead of staying, calling 9-1-1 and rendering aid, this driver likely killed or aggravated injuries.

Bicycle helmets are only rated for 20kph impacts.

This seems a good argument for lower speed limits in town.
Of course, if the roads "feel" as if they are safe when faster, cars will still drive faster.
Making roads that are safe but don't feel safe slows drivers down.

Kinetic injury increases as the square of speed.
An impact at 40kph is MUCH safer than at 50kph.

Essential physics
The kinetic energy involved in a motor vehicle collision is proportional to the square of the speed at impact. The probability of a fatality is, for typical collision speeds, empirically correlated to the fourth power of the speed difference (depending on the type of collision, not necessarily the same as travel speed) at impact,[5] rising much faster than kinetic energy.

A report from the British Columbia Ministry of Transportation includes in its summary the finding that the incidence of crashes depends more on variations in speed between vehicles than on absolute speed, and that the likelihood of a crash happening is significantly higher if vehicles are traveling at speeds slower or faster than the mean speed of traffic

D: too slow is as dangerous as too fast.
I drive on the highway up north some weekends to work in construction.
I don't want speeding tickets to drive up my insurance, or make me lose my license. So I stay only 10 kph above the speed limit.
Very few drivers are happy with this speed.
I'm sure going slower would cause road rage incidents.
Where these people are going in such a hurry is beyond me.
I just leave on time.

My co-renter said he hitches a ride with an older lady sometimes.
She drives the speed limit, right on the dot - in the passing lane.
Meaning people pass unexpected on the right.
SHE is every bit as dangerous as some yahoo weaving in and out of traffic at 20-30kph over the speed limit.

On the highway, there is a bewildering subset of the speeder/passer type.
They'll ride behind me within a second of travel distance for many minutes.
Irate drivers behind them then need to pass multiple vehicles to pass.
Oddly, such a driver will skip many fine opportunities to pass, only to pass finally in less than ideal conditions as their patience runs out.
An odd and dangerous combination of speeding and timidity.

Creating three seconds of reaction time also drives folks bonkers.
These people will travel within 1-2 seconds of the next car.
Leaving almost no time to react in an emergency.

In poor conditions, such as poor visibility or road surface, this combination causes accidents.
I occasionally read of huge multi-vehicle pile-ups on highways during severe fog.

Relating to the story, who will ever know if another second of reaction time would have averted this tragedy?

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