The cost of 80 MPH speed limits

[PressEnter[]]

I don't know that it was better at 75 than 65, but I had a '91 Integra, and it redlined at 8,000 RPM's and I think the next gen version went up to 9,000. They liked the high revs, and I got 35 mpg even with the lead foot I had back then.

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As for Utah, I agree with Razor. People will do 80 anyway, let them have it, and let us have the slow lane.

[darcane]

Originally Posted by PaleMelanesian

Prove it. It might be the first car to accomplish that feat.

Here's a thread with 50 different cars tested, and past 45 mph they all lost mpg with increasing speed.
http://ecomodder.com/forum/showthrea...you-15182.html

I'm not backing up Tippey's claim (and I'm sure he can't either)...

But my old Corvette would get better mileage at 65mph than 55mph. IIRC, 3.31 gears in the rear end and 0.5:1 6th gear put 55mph at about 1100rpm. The LT1 had lots of low rpm torque, but it still couldn't keep me going at 55mph in 6th, so I'd have to downshift. 60mph was really the minimum speed I could stay in 6th gear other than going down a hill.

The Corvette that Darin tested had another 1.3L and 205hp MORE than my '94 (That's like adding a Hayabusa engine to an already fast sports car...). I suspect this is why he was able to keep it moving at 850rpm in 6th.

[trooper Tdiesel]

make's for more fun on the down grades

with that high of speed you can really coast.



on the flip side ive driven in those test areas in UT and being loaded down at 50/60 mph its kinda freaky having people fly by at 80/85
id say in that area people adhered to the "keep right rule" much better then the rest of the country

[LeanBurn]

Having driven in Utah just recently...aren't they already going 80+ already? That I-15 in Utah is crazy already...lots of accidents...bumping the limit to 80mph would mean they would just go faster...scary.

My 1997 gas suburban 5.7L easily gets 15mpgUS at 60mph fully loaded with gear and kids in the winter.

[darcane]

Originally Posted by LeanBurn

Having driven in Utah just recently...aren't they already going 80+ already? That I-15 in Utah is crazy already...lots of accidents...bumping the limit to 80mph would mean they would just go faster...scary.

My 1997 gas suburban 5.7L easily gets 15mpgUS at 60mph fully loaded with gear and kids in the winter.

Yes, they generally are going 80+. And no, rasing the speed limit won't significantly alter the speeds they are driving. Changes in fuel costs should be minimal, since speeds won't really change.

Study after study has been made on this topic. Generally, the speed limit should be set at or close to what the 85th percentile of drivers are already driving at. This is probably how Utah determined 80mph for these roads. Changing speeds does not appear to increase or decrease the number of accidents. This does have a LARGE increase in drivers complying with the speed limits.

One of the most well-known studies is this one:
http://www.fhwa.dot.gov/publications...7084/97084.pdf

Here are some of the Key Findings:
• A review of the before and after speed data at each site revealed that differences in mean speeds, standard deviations of speeds, 85th percentile speeds, and other percentile speeds were generally less than 2 mi/h (3.2 km/h) and were not related to the amount the posted speed limit was changed.

• By defining driver compliance as the number or percentage of drivers that travel at or below the posted speed limit, major changes in compliance occurred when speed limits were raised or lowered. However, as reflected in small changes in vehicle speeds, driver behavior did not change, but the standard for measuring compliance, i.e., posted speed limit, changed.

• There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes or fatal and injury crashes changed when posted speed limits were either lowered or raised.
• There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes changed when posted speed limits were lowered more than
5 mi/h (8 km/h) below the 85th percentile speeds.
• There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes changed when posted speed limits were raised to within 5 mi/h (8 km/h) of the 85th percentile speeds.

[trooper Tdiesel]

the inter state system was intended to have a speed of 75 when construction permitted.
corners are not to be tighter then 45 mph and 6% grade "one oddty on the grade in CO state at 7%"
Interstate Highway standards - Wikipedia, the free encyclopedia

[Vman455]

Originally Posted by nemo

Time cant be saved, but used more efficiently. At the end of the trip the person sit in front of the tube, he has not gained anything. If that person use the extra time during the trip to say, have conversation with son or daughter it has not been wasted.

Exactly. I'm sick of these hypothetical "value of my time" arguments as an excuse for profligate consumption. I can estimate my time is worth $20,000/hour, but if I'm not actually working during whatever time I've specified and not actually getting paid $20,000/hour for it, it's absolutely meaningless. Every minute of every day that I'm not working and earning money is, by their logic, "wasted," and I should minimize the time it takes to do...everything else, regardless of actual cost.

Or, I can keep repeating the word "value," and eventually--value--maybe I'll--value--see the light. Value.

Value.

[wdb]

Originally Posted by LeanBurn

Having driven in Utah just recently...aren't they already going 80+ already?

You don't have to go to Utah. They're doing 80+ every morning on the PA Turnpike between King of Prussia and Willow Grove. Even the far right lane is at or above the limit.

[slowmover]

We've had 80-mph on IH-10 in western Texas for a while. 75-mph elsewhere. I will say that the traffic, already low, keeps itself spread out better with the higher limit. But, if you're running 65 (as I do in the Peterbilt) that overtaking traffic comes up quite fast so one has to be aware of the sheeple (asleep at the wheel) suddenly realizing they're about to hit a big bow wave from the 18-wheeler.

As said above, the "time savings" is all about having the TV remote in hand as soon as possible. And wearing out the car prematurely. Fuel mileage is just a measure of how lightly one treats the vehicle in getting a job done, not much of an end in itself as vehicle life is the paramount concern.

The high speed runs (above 60-mph) need to be in excess of 300-miles before the time versus fuel penalty favors higher speeds.

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