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April 30, 2017

"Getting There" - Who Sets Our Speed Limits ?

Crawling along I-95 the other day in the usual bumper-to-bumper traffic, I snickered when I noticed the “Speed Limit 55” sign alongside the highway.  We wish!
Of course, when the highway is not jammed, speeds are more like 70 mph, with the legal limit, unfortunately, rarely being enforced.  Which got me thinking:  who sets speed limits on our highways and by what criteria?
Why is the speed limit on I-95 in Fairfield County only 55 mph but 65 mph east of New Haven?  And why is the speed limit on I-84 just 55 mph from the NY border to Hartford, but 65 mph farther east in “the Quiet Corner”?  Does the eastern half of the state get a break because nobody lives there?
Well, you can blame the Office of the State Traffic Administration (OSTA) in the CDOT for all the above.  This body regulates everything from speed limits to traffic signals, working with local traffic authorities (usually local Police Departments, mayors or Boards of Selectmen).
OSTA is also responsible for traffic rules for trucks (usually lower speed limits),  including the ban on their use of the left hand lane on I-95 in most places.
It was the Federal government (Congress) that dropped the Interstate speed limit to 55 mph in 1973 during the oil crisis, only to raise it to 65 mph in 1987 and repeal the Federal speed limit altogether in 1995 (followed by a national 21% increase in fatal crashes),  leaving it to each state to decide what’s best.
In Arizona and Texas that means 75 mph while in Utah some roads permit 80 mph.  Trust me… having recently driven 1000+ miles in remote stretches of Utah, things happen very fast when you’re doing 80 – 85 mph!  Fast means dangerous.
Driving too slow can also get you in trouble as many states are now ticketing drivers hanging out in the left-hand passing lane if they’re slowing down traffic.
About half of Germany’s famed Autobahns have speed limits of 100 km/hr (62 mph), but outside of the cities the top speed is discretionary. A minimum of 130 km/hr (81 mph) is generally the rule, but top speed can often be 200 km/hr (120 mph).
Mind you, the Autobahn is a superbly maintained road system without the bone-rattling potholes and divots we enjoy on our highways.  And the German-built Mercedes and Audis on these roads are certainly engineered for such speed.
American cars are designed more for fuel efficiency than speed. Best gas mileage is achieved by driving in the 55 – 60 mph range.  Speed up to 65 mph and your engine runs 8% less efficient.  At 70 mph the loss is 17%.  That adds up to more money spent on gasoline and more environmental pollution, all to save a few minutes of driving time.
But an even bigger for the loss of fuel efficiency is aerodynamic drag, which can eat up to 40% of total fuel consumption.  Lugging bulky roof-top cargo boxes worsens fuel economy by 25% at interstate speeds.  So does carrying junk in your trunk (or a lot of passengers!):  a 1% penalty for every 100 pounds.

Even with cheaper gasoline, it all adds up… at any speed.

Reposted with permission of Hearst CT Media.

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