Slashdot Mirror
Montana Lawmakers Propose 85 Mph Speed Limit On Interstates
HughPickens.com writes AP reports that Montana lawmakers are drafting bills that would raise the daytime speed limit on Montana interstate highways from 75 to 80 and possibly as high as 85 mph. "I just think our roads are engineered well, and technology is such we can drive those roads safely," says Art Wittich. He notes that Utah, Wyoming, and Idaho have raised their speed limits above 75, and they haven't had any problems. Drivers on German autobahns average about 84 mph. State Senator Scott Sales says he spent seven months working in the Bakken oil patch, driving back and forth to Bozeman regularly. "If I could drive 85 mph on the interstate, it would save an hour," says Sales. "Eighty-five would be fine with me."
A few years ago Texas opened a 40 mile stretch on part of a toll road called the Pickle Parkway between Austin and San Antonio. The tolled bypass was supposed to help relieve the bottleneck around Austin but the highway was built so far to the east that practically nobody used it. In desperation, the state raised the toll road speed limit to 85 mph, the fastest in the nation. "The idea was that drivers could drop the top, drop the hammer, crank the music and fly right past Austin," says Wade Goodyn. "It's a beautiful, wide-open highway — but it's empty, and the builders are nearly bankrupt."
The national maximum speed limit was repealed under Bill Clinton so federal funding is not an issue.
Safety is an issue. Crashes on highways are no more frequent at higher speeds so long as they are designed for it, they are however more deadly. In Germany you have two additional things that make it possible to have high or no speed limit on intercity highways. First, the driver training is of much higher quality, you will never see anyone changing lanes without signalling on the autobahn. Second, there is generally a parallel slower road. If an 85 mph road is the only option then you will have people who are little tired or had a glass of wine with dinner on it. Not a recipe for success.
The difference in gas miliage between 45-50 MPH and 70-75 seems to be far more influenced by traffic conditions
Yes.... perhaps we have been measuring the wrong thing all along. Miles driven are not fungible.
We could take a standardized mile, but it would not reflect the real world.
Instead we should say...
The total fuel consumption rate accelerating from 0 to 65, maintaining speed at 65 and driving a distance from point A to point B is X.
X forms a "baseline"
Next you need to add realistic random traffic to the road, and an intelligent agent which attempts to maintain 65 while it is safe to do so.
And you obtain a "second baseline"; real-world gas consumption.
Then if you want to decide whether a different speed limit other than 65 is beneficial or not, you need to make the adjustment, and compare the results against the second baseline over a few thousand trials with a representative sample of travelers.
The ideal circumstances on a road by yourself does not reflect this complex system, and simple physics cannot even solve the N body problem, let alone this one; the only way to come at a decent answer is to experiment and gather the statistics.