3 ms·

Raising the speed limit to the 85%/15% ratio isn't necessarily the safest way to handle the driving. If there's a road where more than 15% of drivers are going

Raising the speed limit to the 85%/15% ratio isn't necessarily the safest way to handle the driving. If there's a road where more than 15% of drivers are going faster than the speed limit, one option is to raise the speed limit, but the other option is to change the road so people won't drive so fast on it.

colanderman 12y ago
That would likely make the road more dangerous for the 85% who drive under the limit. Like any engineering project, roads must be designed with headroom…
- mikeash 12y ago
  That doesn't have to be the case. There are ways to make a road where people want to drive more slowly but that isn't any less safe.
thaumasiotes 12y ago
This only makes sense as a solution to the problem "some people are going faster than the little sign says they should". By design, it doesn't make anyone any safer; it makes them less safe. What problem are we trying to solve?
peatmoss 12y ago
Exactly. Ideally, speed limits are an expression of policy that reflect the normative values and desires of a jurisdiction. The best case would be for us to build roadways that reinforce those values. Many roadways in the US were engineered under a set of assumptions that are incongruous with modern empirical understanding and with modern values. Wide roadways with big turning radii were thought to be safer. Turns out that encourages behaviors that are less safe for a multitude of roadway users. Similarly, there was a 20th century modernist notion that we should use the car for everything. Our bodies (everything from stress measured by cortisol levels, to obesity, to heart disease) object. The 21st century task of planners is to figure out how to retrofit a system built around monoculture into a system that can accommodate a larger aggregate number of people. Part of that is traffic calming.

3 ms·

Raising the speed limit to the 85%/15% ratio isn't necessarily the safest way to handle the driving. If there's a road where more than 15% of drivers are going

by tunesmith 12y ago

colanderman 12y ago
That would likely make the road more dangerous for the 85% who drive under the limit. Like any engineering project, roads must be designed with headroom…
- mikeash 12y ago
  That doesn't have to be the case. There are ways to make a road where people want to drive more slowly but that isn't any less safe.
thaumasiotes 12y ago
This only makes sense as a solution to the problem "some people are going faster than the little sign says they should". By design, it doesn't make anyone any safer; it makes them less safe. What problem are we trying to solve?
peatmoss 12y ago
Exactly. Ideally, speed limits are an expression of policy that reflect the normative values and desires of a jurisdiction. The best case would be for us to build roadways that reinforce those values. Many roadways in the US were engineered under a set of assumptions that are incongruous with modern empirical understanding and with modern values. Wide roadways with big turning radii were thought to be safer. Turns out that encourages behaviors that are less safe for a multitude of roadway users. Similarly, there was a 20th century modernist notion that we should use the car for everything. Our bodies (everything from stress measured by cortisol levels, to obesity, to heart disease) object. The 21st century task of planners is to figure out how to retrofit a system built around monoculture into a system that can accommodate a larger aggregate number of people. Part of that is traffic calming.