Texas to open fastest US highway with 85 mph limit

quote:

---

Texas will soon open a stretch of highway with the highest speed limit in the country.

The Texas Transportation Commission has approved the 85 mph speed limit for a 41-mile-long toll road near the increasingly crowded Interstate 35 corridor between Austin and San Antonio.

The road runs several miles east of the interstate between two of the state's largest metropolitan areas.

---

I thought Montana had some higher (or no limits)?

And you'd think that some of the desolate parts of I-40, I-20 and I-10 would bet high limits first.

I frequently exceed that on 75 in Dallas.

I mean, um, only in Mexico.

I think they are referring to actual speed limit restrictions. I know when we drive to work cows in New Mexico with a friend one summer there were some stretches they called 'unpatrolled' or something like that. They had signs warning that there was no cell service, no gas stations, no emergency personel, and drive at your own risk. There was no speed limit, but that does not equate to highest allowable speed limit. Would be my guess at least.

In all seriousness - for a Toyota bland, Kia whatever, etc (boring 'normal' cars) - at what speed does it become less economic to drive that fast? There's usually that one speed (most often RPM based) where fuel economy just plummets.

It happens in the 65-75 region in my Dodge 1500. I'll get almost to the 75 mark that is allowed now, but really don't like to pass it. The numbers just start dropping. The 18-wheeler drivers still won't (or aren't allowed by their carriers) over 70. Drives where in the past I could set the cruise and just go, now have me weaving in and out of lines of 18-wheelers.

Yeah I really liked the year or so we got of one speed limit for all.

Where that dropoff fuel economy number is for smaller cars, I too am curious.

While my ride gets near 30MPG on the highway, not at 85. I get closer to 27MPG around 3500 RPM and that is at 75-80, I imagine my milage would drop a bunch as the power curve goes up around 4000RPM.

quote:

---

I thought Montana had some higher (or no limits)?

---

They got rid of the no-limits some years ago.

My Ranger is great until precisely 68 mph (according to the speedo) - the Lotus is 83 mph, then it drops horribly on MPG.

So I guess you can do 85 all you want, but you'll be getting Hummmer mileage no matter what you drive.

quote:

---

The 18-wheeler drivers still won't (or aren't allowed by their carriers) over 70. Drives where in the past I could set the cruise and just go, now have me weaving in and out of lines of 18-wheelers.

---

at $4+ per gallon for diesel, and economy of 6-8 mpg, trucks go slow

18 wheeler at 85? LOL 1-2 mpg

Years ago (I'm talking about 1990) I had to be in Oklahoma City early in the morning, and had work to do before, so I left at about 3am.

I guarantee there was not a single truck on I-40 that was traveling slower than 80-85. Damnedest thing I ever saw.

But I agree with the above, even where the speed limit is 75, trucks seldom break 70, or even 65. Blame GPS tracking, I guess.

Remember the equation for air drag.


It is a function of speed and surface area (cross sectional). As velocity increases, drag is squared (i.e., if you double your speed, you quadruple your drag).

Not hard to find the point of diminishing returns.

~egon

Last trip up to dfw I was coming back on 45 and there were 2 state of Texas 18 wheelers driving 85, I'm sure the other truckers were jealous.
I know that all of the vehicles I have ever had, would be way past the ideal mpg at 85. Actually surprised of everything I have ready about this new speed limit there had been no mention of the gas mileage.

If you look real closely at the pic below of a stretch of autobahn in Germany, you can see that the highway is slightly below-grade/below ground level and that trees are lined next to it. This minimizes crosswinds. If Texas is going to pioneer high speed travel in America, start taking more notes from Germany.



Also it's not just the autobahn, even their rural country highways are below-grade to minimize crosswinds and to make a safer road. Cresting a hill in Germany? Rarely. Damn Europeans just putting so much thought into everything they do, lazy? Hardly.



[This message has been edited by crob (edited 9/7/2012 8:01a).]

I take that toll road to get the the lakehouse, it's the best part of the drive.

How many severe t-storms are there in Germany? Placing roads below grade has problems as well.

quote:

---

How many severe t-storms are there in Germany? Placing roads below grade has problems as well.

---

Not as much as Texas, but they do have thunderstorms during the Summer. Apparently they're having a lot more thunderstorms now due to climate change.

Texas could take notes from those wacky Dutch liberals and put up plexiglass walls alongside their highways.



[This message has been edited by crob (edited 9/7/2012 8:17a).]

With regards to trucks... Our VFD just got a brand new 100' aerial (ladder truck), darn thing is governed at 68 by the manufacturer.

Germany's rural roads... Could they be below grade due to centuries of erosion on dirt and cobble roads? A lot our our rural dirt roads are below grade due to this.

My suburban gets decent mileage at speeds up to 78 or so, at steady highway driving. The truck gets about the same mileage up to 75. The Xterra...it don't like to go fast. It has a sweet spot in the gearing at about 65, and over that the RPMS go too high and you burn gas faster.

My Z06 gets 23mpg at 90....

I get 46mpg at or above 80 and 51mpg at 70.

I wouldn't feel comfortable driving 90 continuously in the brand new Fusion rental I had last time I was in Odessa. The damn thing floated all over the road and damn near took off if I hit 100.

quote:

---

Germany's rural roads... Could they be below grade due to centuries of erosion on dirt and cobble roads? A lot our our rural dirt roads are below grade due to this.

---

In some cases maybe, but I doubt it because the road in the pic in my earlier post is B286 between Maibach and Schweinfurt, which has been upgraded recently because it is near one of the newest autobahns, the A71. That started the construction phase around 1999 (building bridges and such) but wasn't until 2002 that the land started to be cleared (carving through hills, creating hills, etc). A71 finished construction around 2007 I believe.

There's a lot of new roads that are new as well, the B26 bypass around Bergrheinfeld, the B19 bypass around Werneck, etc. A lot of them that I never had a chance to drive on because they didn't exist when I lived in Pfersdorf-Poppenhausen outside of Schweinfurt, including the A71.

Germany does spend a LOT more time making better roads, primarily because they have a lot less road miles with which to work compared to the allocated budget.

That is true, now they're helping the Chinese in building their freeway/railway networks. Along with most of Western Europe can thank the Germans for the engineering know how regarding road construction.

All the more quicker to get to your favorite vacation spot in France, Poland and Belgium.

P_bubel, I'd appreciate you not joking about the path of destruction the Nazi's made as they conquered new territory. Many people lost their lives, including one of my grandfathers.












He fell off a guard tower

Germans joke that Hitler built good roads, but I think they're tired of the guilt that Americans constantly place on them from what happened in WW2. Probably why they prefer to do more business with China than the USA presently.

quote:

---

Germans joke that Hitler built good roads, but I think they're tired of the guilt that Americans constantly place on them from what happened in WW2. Probably why they prefer to do more business with China than the USA presently

---

quote:

---

Germans joke that Hitler built good roads, but I think they're tired of the guilt that Americans constantly place on them from what happened in WW2. Probably why they prefer to do more business with China than the USA presently.

---

quote:

---

The 18-wheeler drivers still won't (or aren't allowed by their carriers) over 70.

---

JB Hunt trucks are governed at 62 mph. As cheap as those @&#%ers are, I can almost guarantee that is the exact optimal speed for fuel economy, without causing an undue increase in trip time. Unless you are charging a premium for time sensitive deliveries, even driving 70 will eat a huge portion of your profit margin.

I would imagine most passenger cars hit their peak mpg somewhere in the 60s, but the drop in mpg would be relatively low until 75 or so. That is my highly uneducated opinion.

We were invited!
Punch was served!
Check with Poland!
I will hear no more insinuations about the German People!
Nothing bad happened!

quote:

---

The 18-wheeler drivers still won't (or aren't allowed by their carriers) over 70.

---

DO NOT, pull into the left lane if you see an owner/operator bull wagon in the rearview until you make sure it's not getting bigger in your view.

All kidding aside, at speed over 70 - I worry more about tires than horsepower or economy. But that's because my combos get so little use dry rot tires are a concern on the trailers.

I wish they'd change the speed limit south of Dallas on 45. No reason it should be 60 through all those little towns and especially south of Ennis.

quote:

---

you can see that the highway is slightly below-grade/below ground level and that trees are lined next to it. This effectively means you see nothing but boring trees all the way from Hamburg to Munich.

---

FIFY







/not entirely true, but kinda