I remember reading somewhere that either Congress or the FHWA ruled that 90 km/h was
functionally equivalent to 55 mph and thus, when the federal maximum speed limit was
55 mph, states could substitute 90 km/h rather than the clunky 88 km/h. This 88 km/h
speed was used as a justification by many states that metrication was difficult for
speeds if they could only legally post a metric speed that was no higher than the
non-metric 55 mph. As the maximum speed limit has been recalled and states are free
to set speed limits, most go with their design manuals. As most states have metric
design manuals (although they are not currently using them) the speed would be
determined by the design characteristics of the road.
I also believe that equivalences were given as follows:
25 mph = 40 km/h
30 or 35 mph = 50 km/h
35 or 40 mph = 60 km/h
45 mph = 70 km/h
50 mph = 80 km/h
55 mph = 90 km/h
60 mph = 100 km/h
65 mph = 110 km/h
70 mph = 120 km/h
75 mph = 130 km/h
As you can see, with metric, you get slightly higher speeds but not drastically so.
>From the MUTCD:
Section 2B.13 Speed Limit Sign (R2-1)
Standard:
After an engineering study has been made in accordance with established traffic
engineering practices, the Speed Limit (R2-1) sign (see Figure 2B-1) shall display the
limit established by law, ordinance, regulation, or as adopted by the authorized
agency. The speed limits shown shall be in multiples of 10 km/h or 5 mph.
Howard, can you add any insight to this?
Phil
-----Original message-----
From: Bill Hooper [EMAIL PROTECTED]
Date: Tue, 20 Jul 2004 12:14:26 -0400
To: "U.S. Metric Association" [EMAIL PROTECTED]
Subject: [USMA:30499] Re: Irish driving
>
> On 2004 Jul 19 , at 10:13 PM, m. f. moon wrote:
>
> > Bill, in California, the 65 mph was "translated" in metric to 100
> > km/h. The
> > law can do what it wants to do.
>
> That's very interesting.
>
> I had heard there where other examples where "someone" insisted that
> the converted value always had to be less than (or exactly equal) to
> the old English value as long as the old English value was still the
> value that was given in the law. While it is true that the law may do
> what it wants, it is also true that only the legislature can pass laws.
>
> Allowing lower officials (who actually do the converting of the signs)
> to make the value greater than specified in the law would be giving
> them the authority to change the speed limits, a power that is vested
> in the legislature and cannot be assumed by those lower officials. I
> wonder how they could get away with it!
>
> Could it be that in California they actually changed the legal speed
> from 60 mph (which equals 96.54 km/h) to 100 km/h (which equals 62.15
> mph)? Or was a special law passed that avoided the question by
> declaring that the metric speeds were only informational and
> approximate, and not the exact legal speed. This latter approach has
> been suggested in some quarters, with the plan that, eventually, the
> law would change to state that the metric speeds were now the legal
> speeds and any old English signs would be considered merely approximate
> and informational.
>
> Regards,
> Bill Hooper
> Fernadina Beach, Florida, USA
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Go Metric America! Or get left behind!
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
