Could more unusual speed limits help improve safety on the roads? Here is one speed limit I saw recently along a road coming out of a shopping plaza:

Most speed limits are in increments of 5. I assume this is, in part, due to standardization of roadways throughout the United States. But, why not throw in some more unusual numbers to catch the attention of drivers? Would I be able to stick to the occasional 13 or 31 or 67 more easily than the standard 15, 30, or 65? If every speed limit was a number off of the 5/10s pattern, they might make the problem worse. The key could be to have some numbers off from typical numbers.

The switch to more digital speedometers in cars could help with this. A good number of speedometers are also in increments of 5 and 10 so matching 13 mph could be hard. If more drivers have digital displays where a 5/10 increment does not exist, then escaping the rigidity of 5/10s could be easier.