As an aside, metric conversions of US customary speed and distances are convenient in that they almost perfectly align to powers of two for typical land speeds.
5 mph ~ 8 kph
10 mph ~ 16 kph
20 mph ~ 32 kph
40 mph ~ 64 kph
80 mph ~ 128 kph
The other common speed limits in the USA are thus bitwise compositions, which Computer Science folks might appreciate:
15 mph ~ 24 kph (16+8)
25 mph ~ 40 kph (32+8)
35 mph ~ 56 kph (32+16+8)
45 mph ~ 72 kph (64+8)
50 mph ~ 80 kph (64+16)
55 mph ~ 88 kph (64+16+8)
65 mph ~ 104 kph (64+32+8)
Had the 1980s US metrication effort succeeded, we could have seen those same limits rounded off to: 25, 40, 55, 70, 80, 90, and 100 or 110 kph.
For reference, common speeds around the world are 15, 20, 30, 50, 80, 90, and 100 kph
As an aside, metric conversions of US customary speed and distances are convenient in that they almost perfectly align to powers of two for typical land speeds.
5 mph ~ 8 kph
10 mph ~ 16 kph
20 mph ~ 32 kph
40 mph ~ 64 kph
80 mph ~ 128 kph
The other common speed limits in the USA are thus bitwise compositions, which Computer Science folks might appreciate:
15 mph ~ 24 kph (16+8)
25 mph ~ 40 kph (32+8)
35 mph ~ 56 kph (32+16+8)
45 mph ~ 72 kph (64+8)
50 mph ~ 80 kph (64+16)
55 mph ~ 88 kph (64+16+8)
65 mph ~ 104 kph (64+32+8)
Had the 1980s US metrication effort succeeded, we could have seen those same limits rounded off to: 25, 40, 55, 70, 80, 90, and 100 or 110 kph.
For reference, common speeds around the world are 15, 20, 30, 50, 80, 90, and 100 kph