Raise the Hammer

Interesting discussion.

I think that Mr. K is only looking at deaths. Not accident rates. He is correct on that. The evidence is clear that pedestrian deaths occur far more readily at higher rates of speeds. However, Notlloyd acknowledged that and so appears to agree with the Coroner as well. Notlloyd said, it's like aircraft crashes. The faster a car goes, the more likely an impact with a pedestrian causes the pedestrian's death. But there is more to it than that.

You have to look at rates of death. Not death per speed but death per usage and/or death per usage and speed (or even more complex variables.) I would add that you also have to look at the sample size and shape as well .

Let's say that there are 10 pedestrian deaths in Hamilton per year on average. If you reduce the speed limit to 30kph given the current road construction, the science says that every year going forward, provided that the current average death rate is largely consistent and the norm, you will continue to have 10 deaths per year going forward (kid running out between parked car, demented person walking out into traffic, drunk driver speeding, teen on cell phone not watching, something like what has happened at queen and Main this year etc. etc.) Plus, people will not obey a blanket 30kph speed limit without major re-engineering.

Now, if you then spend several hundred million dollars and rework the roads to force drivers to reduce speed so as to comply with the 85% rule, you then need to be able to estimate the death rate and determine if it should be done.

Given that the accident rate is unlikely to change significantly (people will still be hit and injured) the question then becomes, how many deaths can we prevent. Is it 5 (50% reduction)?

The City is very large with different types of neighbourhoods. Some of the recent death in Hamilton occurred on major arteries on busy roads at higher speeds. Some occurred at intersections at lower speeds. One lady died who seemed to be fine and likely died because she was elderly and simply fell. Do you have to re-engineer all roads?

Maybe we need to look at where the deaths occurred and look at each part of the city separately. What if the data is that all of the downtown death are already occurring at speeds below 30k and all of the out of downtown death are at above 50K. Do you leave the downtown alone and re-engineer everywhere else?

What if the deaths are random? The actual numbers are not very large. They are far lower today than they were 50 or 75 years ago. Maybe all the engineering in the world will accomplish nothing vis a vis the death rate.

I can’t imagine anyone obeying a 30 kph speed limit on Fennell, or Upper Gage or Mohawk. Maybe they would on Concession (where hardly anyone drives 50kph anyway.)

I think one of the reasons that the Mountain subdivisions north of Mohawk were designed the way they were was to eliminate through traffic and reduce speeds. Hardly anyone can do 50kph in those neighbourhoods and I don’t hear any clamouring from the residents up there for reduced speed limits.

I think what Notlloyd is saying is that it is more complex an issue than simply reducing velocity.

Velocity is a factor in 100% of accidents. So the only way to eliminate accidents is to eliminate any traffic. If the goal is to eliminate pedestrian collisions, you must eliminate traffic.

This all begs a horrible question; how much money do we spend to save five lives?

People want simple answers and simple solutions. However, sometimes the most obvious solution is not the best solution. A blanket reduction in speed limits may actually increase the problem if the 85% rule is true (the corollary is that people’s behaviour being what it is will be such that people will not obey rules they think are wrong.)

Comment edited by CharlesBall on 2014-05-29 11:34:01