One big
American peeve is the push the
US government has been making towards
metric roadway
signage for over
35 years. A
token vestige of
metrification still exists in the form of
Arizona Interstate I-19, from
Tuscon to
Nogales,
Mexico.
I-19 spans 101
km (63
mi), and has served a critical function as one of the main
arteries from
Mexican border areas into Arizona. The
highway was signed in the late 70s, during the
fiasco that was US highway conversion to metric. Arizona has declined to
plaster the exit signs over with US measurements because of the
convenience to Mexicans, yet everyday Americans largely unfamiliar with metric use the road as well.
Compromises have been made.
A
driver entering I-19 is
greeted with "THIS ROAD IS SIGNED IN METRIC", though the road is really an
amalgam of the two systems. I-19 has both
mileposts and, um,
kilometer posts. The kilometer posts face
traffic while the mileposts are at 90 degree angles to the
roadway.
Hazard signs (as for
construction) use US measurements. Speed limits are posted in the familiar American design and in US measurements. In my opinion, having speed limit signs in US measurements only without the
acronym "
MPH" is potentially
dangerous to metric drivers. There is an inherent
contradiction in having distances in km and speeds in mph, but I guess some
legislator thought it more important that the majority American drivers on the road not speed and set the
tempo for the metric drivers. Keep in mind that the speed limit is 75 mph (120 km/h) for the greater part of the highway, so there's a high
probability that drivers are routinely going 90 mph (140 km/h), rendering any signage meaningless. Yet, a metric driver would be forgiven for seeing "75" and interpreting that figure as 75 km/h. I wonder what the driver
accident rate is on a road that combines measurement systems in this fashion.
Though the predictions for a new
halcyon metric era have passed, I think I-19 raises the question of how to deal with America's roadway
borders with
Canada and Mexico.
The most apparent solution is a new push for full bi-measurement within 160 km (100 mi) of the borders, but many states have
prohibitions against funding of metric signage.
Many states with
Canadian borders routinely post dual speed limit signage within 80 km (50 mi) of the
crossings, with
exit distances posted in
mileage only. This may be a nice solution that prevents accidents but serves the needs of the majority of drivers. It's one thing not to understand where you're going, but it's another thing to be going 45 mph on a four lane interstate.
for more information try http://www.arizonaroads.com/interstate/i19.htm