Raise the Hammer

kevlahan, look at how the authors come to the conclusion that one way streets are more dangerous than two way streets...

For example, the low SES group rate for all ages and both
sexes was 33.3. The one-way street rate was 46.4 for all ages and both sexes suggesting that one-way street rates could account for
a 12.1 excess rate of injury

... The authors are suggesting that because the low income group collision number of 33.3 is LOWER than the one way street collision number of 46.4, it must be that one way streets are inherently dangerous, regardless of neighbourhood income status and all the things that follow, like more walking, more playing around traffic, etc.

However, because the authors used three income groups, the total number of collisions that are labeled under "low income" are not as high as they would have been if they had only used two groups, as is the case in table II. In effect, the authors are diluting the number of collisions by adding an extra "intermediate" category, which if it didn't exist, would have increased the number in the low SES group.

>> much more than half the rate would be assigned to the lower SES bin

Okay, but this just strengthens the idea that there is something beyond street configuration that is leading to higher collision rates. If there are more collisions in low SES neighbourhoods, a higher rate than is found on one-way streets, then how can anyone conclude that it is one way streets that are responsible for higher collision rates.

If anything, it is suggestive of something about low income neighbourhoods that is leading to higher rates of accidents.

>> note that the overall rate for all three bins taken together is still 2.5 higher for one-way streets.

That is true. But like I said before, if we don't know the traffic volume per km on one-way streets, then how can we conclude that one way streets are more dangerous. It may simply be that because one- way streets are in more densely populated areas, there is simply more traffic and kids using those streets.