States Boost Speed Limits On Major Highways
Moves Come Despite Concerns Over Safety, High Gas Prices; 80 Miles Per
Hour in Texas

By STEPHANIE CHEN, The Wall Street Journal

With gasoline prices approaching an average of $3 a gallon and Middle
East strife escalating, it might seem like a bad time to encourage
drivers to burn even more fuel. But speed limits on stretches of
freeways around the country are rising -- just in time for summer road
trips.

States around the country, including Texas and Michigan, have recently
increased speed limits on hundreds of miles of interstate highways and
freeways. Other states are expected to follow soon.

Near Detroit, drivers long confronted by signs telling them to go no
more than 55 miles per hour or 65 mph are seeing new signs with 70 mph
speed limits. By November, cruising at 70 mph will be allowed on nearly
200 miles of road, including parts of Interstate 75 and M-59, a major
suburban route. Texas has begun erecting 80 mph signs along 521 miles
of I-10 and I-20 in 10 rural western counties, giving them the highest
speed limit in the U.S. In September, Virginia is likely to boost the
speed limit on I-85 near the North Carolina border to 70 mph from 65
mph. Driving faster may get people to their destinations more quickly,
but it can also add to the rising cost of owning a car. The Department
of Energy estimates that every five miles per hour a person drives
above 60 mph costs an extra 20 cents a gallon, for a fuel-efficiency
loss of 7% to 23%, depending on the type of car and gas. That's because
higher speeds increase aerodynamic drag on a car, requiring more
horsepower. Over a year, it costs roughly an additional $180 in gas to
drive 75 mph instead of 60 mph, according to the Environmental and
Energy Study Institute, which promotes energy efficiency and renewable
energy.

Bruce Jones, director of the Minnesota Center for Automotive Research
at Minnesota State University in Mankato, calculates from federal data
that driving 75 mph, rather than 65, would increase gas expenses by
about $121 a year for a 2006 Pontiac G6 sedan and $217 for a Hummer.

But lawmakers in Texas, Michigan and other states say that raising
speed limits will make roads safer by restoring credibility to
speed-limit signs and making driving speeds more uniform. While
transportation engineers acknowledge that raising speed limits hurts
fuel efficiency, they contend that careful studies of traffic flow and
driver behavior show that many speed limits are actually too low. Most
drivers who exceed these low speed limits are doing it safely. "In
Texas, they are already going [80 mph] anyway," says Carlos Lopez,
director of traffic operations at the Texas Department of
Transportation. "People are driving where they feel comfortable."

John Stinson, a home remodeler who lives in Mount Clemens, Mich., says
the new 70 mph speed limit on the Van Dyke Expressway gives him an
extra "cushion" during his commutes of as much as 200 miles throughout
southeastern Michigan. "There won't be the slow people holding everyone
up and the fast people weaving in and out," he says.

It has long been thought that higher speed limits lead to more road
fatalities. But the link has been disputed. Many modern roads are built
to accommodate vehicles moving at faster speeds, and many drivers are
now protected by front and side airbags.

In 2005, the number of injuries per mile on the U.S. interstate-highway
system fell to the lowest level since it was established by President
Eisenhower in 1956, according to the National Highway Traffic Safety
Administration. But Russ Retting, a senior transportation engineer at
the Insurance Institute for Highway Safety, a research group funded by
auto insurers, says fatality rates were 17% higher in states that
raised speed limits from 1995 to 1999 than in states that didn't.

"It's difficult to generalize information out of all the noise," says
Karl Zimmerman, an assistant research engineer at Texas Transportation
Institute, part of Texas A&M University, adding that many crashes are
caused by weather, driver inattentiveness and road conditions that
aren't connected to speed limits.

Recent speed-limit increases in Indiana, Iowa, Michigan and Texas are
the latest in a string of jumps dating back to the 1995 repeal of the
nationwide 55 mph speed limit, mandated by Congress in 1974. More than
a dozen states quickly gave drivers the freedom to push the pedal
closer to the metal, especially in Western and Midwestern states with
less congestion, scattered populations and wide, straight interstates.
A total of 31 states now have a maximum speed limit of at least 70 mph,
according to the Insurance Institute for Highway Safety.

Shaunee Lynch, spokeswoman for the Kentucky Transportation Cabinet,
says the state agency hopes that lawmakers will agree early next year
to raise the speed limit to 70 mph from the current 65 mph to keep up
with surrounding states that already let drivers go that fast. Drivers
aren't happy when signs at the border warn them to slow down, she says.
In Louisiana, state Sen. Joe McPherson says he plans to revive his
unsuccessful bill that would have raised the speed limit on Louisiana
interstates to 75 mph from 70 mph and on limited-access freeways to 70
mph from 65 mph. "If 35 mph is more fuel-efficient than 55 mph, then
why don't we all just drive 35 mph?" he says in response to
fuel-efficiency critics.

State lawmakers typically set statewide speed limits, with
transportation officials determining which stretches of roads can
safely handle faster-moving traffic. It isn't clear if the urge to
increase speed limits on interstates will trickle down to smaller roads
and streets, usually controlled by local officials.

Speed limits for cars and trucks can vary, with Illinois restricting
truck drivers to no more than 55 mph -- or 10 mph slower than the
maximum interstate-highway speed for cars. A bid to increase the speed
limit for trucks to 65 mph was vetoed by the Illinois governor in 2004.
In Michigan, the speed limit for trucks will be raised to 65 mph by
November -- but that still keeps them slower than cars.

It is too soon to tell whether some speed demons will see rising speed
limits as an excuse to go even faster. But Michigan transportation
officials are encouraged by the results of boosting the speed limit on
Interstate 69 near Flint to 70 mph last August. When the speed limit
was 55 mph, about 1.8% of all vehicles zipped along at more than 80
mph. That fell to 1% after the change.

July 20, 2006

Someone else calculated the cost of their gasoline consumption per hour.
It came to something like $9.00 per hour. If one's billing rate is more
then an order of magnitude higher than this, it still pays to go faster.

Federal Highway Administration and HTHSA keep statistics.

When the national maximum speed limit was set to 55 back in '74 the
immediate result was 8000 fewer highway deaths per year a 16% decline.
When the law was repealed in the 80's and states started to introduce
higher speed limits the reverse happened. Typically when the speed limit
was raised from 55 to 65 these locales saw a 15%-20% increase in highway
deaths. Of course volumes have been written about how these statistics
are just coincidences.

-jim

It is a reasonable speed level that will improve milage for most cars.
Vettes and the like maybe not.

If you are a traffic guy that ones to set limits that will require a
minimum amount of enforcement then go the the 85th percentile.  But if
you want to minimize both the burning of gasoline and the number of
accidents then set a reasonably low limit and enforce it.  Miscreants
will get the message soon enough.