> And "The lane widths in the analyses conducted were generally either not statistically significant or indicated that narrower lanes were associated with lower rather than higher crash frequencies."
And this is the problem. "Not statistically significant" means that the effect is very small. This is what you would expect if narrower lanes make driving more dangerous but then drivers compensate by being more careful; they approximately cancel each other out. The author is making much hay out of the possibility that drivers might be not only compensating but overcompensating for the reduction in safety, theoretically causing a (small) net increase in safety.
The fallacy of this is that intentional danger is not the only possible way to increase driver vigilance. As one example, we could promote self-driving cars. That allows us to capture a much larger safety increase because the increase doesn't have to be weighed down by the counterbalancing cost of having narrower lanes and less room to maneuver.
As a quibble, "not statistically significant" means "cannot tell if there was an effect, either positive or negative, because it's smaller than the noise." The only difference is that one can't use it to argue that it 'theoretically [caused] a (small) net increase in safety'.
You use the phrase "intentional danger". The flip side is that "illusory safety." A 12' lane may feel safer even though it actually isn't. But it feels like you stress the "intentional danger" part when the label is irrelevant - the questions are the number and severity of crashes, of human injury, of overall traffic capacity, etc. How one labels the emotional aspect of the driver's internal state isn't relevant to the outcomes.
Also, as secabeen pointed out, driver vigilance isn't the only concern. To add another one 12' of road surface is simply more expensive to repair, clean, and replace than 10' of surface.
Regarding self-driving cars - sure, but how does that change anything in the next 10-20 years of road design? The underlying factors won't change unless a large percentage of vehicles are self-driving. You might as well argue that enforcing a 10mph speed limit would be safer as well, as another example of a solution which, even though correct should it occur, won't affect anyone's planning now.
Right, but you're missing the author's point. Smaller lanes make the space feel more human-scale and friendly to pedestrians and bikers. Traffic engineers argue that larger lanes are safer. These studies show there is no evidence of that. Given that smaller lanes are more appealing, and have no measurable impact on safety, the trend towards larger lanes should be reversed, and smaller lanes implemented on new roads.
And this is the problem. "Not statistically significant" means that the effect is very small. This is what you would expect if narrower lanes make driving more dangerous but then drivers compensate by being more careful; they approximately cancel each other out. The author is making much hay out of the possibility that drivers might be not only compensating but overcompensating for the reduction in safety, theoretically causing a (small) net increase in safety.
The fallacy of this is that intentional danger is not the only possible way to increase driver vigilance. As one example, we could promote self-driving cars. That allows us to capture a much larger safety increase because the increase doesn't have to be weighed down by the counterbalancing cost of having narrower lanes and less room to maneuver.