Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

[zoog]

No surprise, of course, just another milepost along the highway of peak cheap oil. Article contrasts the freewheeling days of the past with modern trucking company operations where engine governors limit how fast the trucks can go, and satellite-linked surveillance equipment tracks things like location, speed, and even gearing.

...To truckers across the U.S., the new controls—the industry's latest attempt to wring better economy from its fleets—spell the end of a romantic age, powered by cheap diesel, when drivers could do pretty much as they pleased on the open road....

wsj

[Chomsky]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

No surprise, of course, just another milepost along the highway of peak cheap oil. Article contrasts the freewheeling days of the past with modern trucking company operations where engine governors limit how fast the trucks can go, and satellite-linked surveillance equipment tracks things like location, speed, and even gearing.

...To truckers across the U.S., the new controls—the industry's latest attempt to wring better economy from its fleets—spell the end of a romantic age, powered by cheap diesel, when drivers could do pretty much as they pleased on the open road....

wsj

To me, the key observation is:

Under the sterner governor, Mr. Kelley said, he covers less blacktop, crimping his take-home pay, since truckers are paid by the mile.

Rising oil prices = lower wages in this case

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Slow speed limits force motors to use more fuel because they don't run efficiently. And slow speed limits increase traffic congestion by increasing the amount of time vehicles have to travel. This latter effect forces motors to idle more and also run below their most fuel-efficient RPM on the road.

In Canada, speed limits should be doubled, especially in British Columbia. Imagine, four-lane highways with 80 kph speed limits
(50 mph ) and two-lane highways in BC with 50 kph (31 mph) limits! It's a joke, yet it's reality in British Columbia..... The year is 2011, not 1911.

If trucking companies are upset about the cost of fuel, maybe they should be pressuring government to double speed limits.

[thriftyandboringinohio]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Slow speed limits force motors to use more fuel because they don't run efficiently. And slow speed limits increase traffic congestion by increasing the amount of time vehicles have to travel. This latter effect forces motors to idle more and also run below their most fuel-efficient RPM on the road.

In Canada, speed limits should be doubled, especially in British Columbia. Imagine, four-lane highways with 80 kph speed limits
(50 mph ) and two-lane highways in BC with 50 kph (31 mph) limits! It's a joke, yet it's reality in British Columbia..... The year is 2011, not 1911.

If trucking companies are upset about the cost of fuel, maybe they should be pressuring government to double speed limits.

From AccessScience.com
http://accessscience.com/content/Tra...amics/YB100085




The total vehicle drag is defined by the equation below,

(1)

where C_D is the vehicle drag coefficient, A is the vehicle cross-sectional area, ρ is the air density, and U is the vehicle speed. For a typical tractor-trailer, the drag coefficient varies widely between 0.5 and 0.8, depending on the vehicle shape and configuration, and the cross-sectional area is roughly 108 ft² (10 m²). It is clear from the above equation that the total drag can be lowered through streamlining the vehicle (decreasing C_D), reducing the cross-sectional area of the vehicle, and decreasing the vehicle speed. The first two approaches in drag reduction can be achieved by either modifying the geometry of the vehicle or by flow conditioning. The flow conditioning works by means of air injection at high or low speeds into the flow field around the vehicle to reproduce a flow field caused by a more streamlined body. Since the drag is a function of speed squared, a significant aerodynamic drag reduction can also be achieved simply by reducing the vehicle speed.

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

From AccessScience.com
http://accessscience.com/content/Tra...amics/YB100085




The total vehicle drag is defined by the equation below,

(1)

where C_D is the vehicle drag coefficient, A is the vehicle cross-sectional area, ρ is the air density, and U is the vehicle speed. For a typical tractor-trailer, the drag coefficient varies widely between 0.5 and 0.8, depending on the vehicle shape and configuration, and the cross-sectional area is roughly 108 ft² (10 m²). It is clear from the above equation that the total drag can be lowered through streamlining the vehicle (decreasing C_D), reducing the cross-sectional area of the vehicle, and decreasing the vehicle speed. The first two approaches in drag reduction can be achieved by either modifying the geometry of the vehicle or by flow conditioning. The flow conditioning works by means of air injection at high or low speeds into the flow field around the vehicle to reproduce a flow field caused by a more streamlined body. Since the drag is a function of speed squared, a significant aerodynamic drag reduction can also be achieved simply by reducing the vehicle speed.

Drag, shmag! I burned through an entire tank of fuel while stuck in a ditch south-west of Flasher, North Dakota while the car was going at zero miles per hour. I flew into the ditch hitting a snow drift that had blown onto the highway, just past a hill-top. I hit that sucker at about 70 MPH. The car flew around backward and into the ditch. The time was 1AM. The tank was full to the top.

All night I was there in the ditch listening to the car radio. I saw lights in the distance, but I knew better than to try to walk through a blizzard on the prairie to try to go to lights on the horizon.

By 7AM, the tank was almost empty. I had burned through an entire tank of gasoline, with some alcohol added to it to keep the fuel-line from freezing. Finally, at 8AM, a North Dakota highway snow-plow came through and pulled my car out of the ditch. I had about given-up, and the tank was onto fumes. If that plow had not come by, I would have froze-to-death when the engine would have stopped running.

Drag is one small part of the fuel efficiency equation, but I think (RPM/ mile of travel) and speed (time to travel) are much more important in fuel economy than the drag co-efficient.

And the other reason why I have gone over to be a speed advocate (just like an adolescent) is that Nixon's (or was it Gerald Ford's ?) 55 MPH limit on America's highways during the 1970s turned-out to be the biggest racket for traffic fines that I had ever seen--- or at least until I moved to British Columbia and witnessed their horse-and-buggy speed limits.

I noticed in B.C, that for the most part, the eco-frauds support the horse-and-buggy speed limits. They think horse-and-buggy speed limits are better for the environment, and they resent car drivers anyway.... I kid you not, but I have actually seen in Victoria, BC where skate-boarders travel faster down streets than car drivers can legally drive.

Oh, where is Flasher, ND? you might ask. Flasher is south-west of Bismarck, ND--- the state capitol. I was travelling north-east out of Rapid City, South Dakota, and making very good time. The road was completely clear of snow, with totally bare pavement, at least until just beyond that hill-top. It was like a re-play of the disaster with the iceberg from out of the darkness and the Titanic in 1912.

[leegs]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Well thanks, you have certainly cleared up any doubts as to your grasp of basic science and logical reasoning ability. iTuliper Chomsky said it best: performance art.

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Well thanks, you have certainly cleared up any doubts as to your grasp of basic science and logical reasoning ability. iTuliper Chomsky said it best: performance art.

I'm just sitting in back of the engineering class and asking some questions because I need help. I'm lost.

In the ditch, my RPM per mile was INFINITE because my distance traveled was zero. Also, my speed was ZERO. (My d/t was zero because d=0.) I had ZERO drag using your equation above because my speed was zero. Yet, I burnt thru an entire tank of fuel. So, put this together into an equation that unites everything: drag, speed, rpm per mile. The equation would yield the fuel efficiency, and then we can solve for the best speed to yield the greatest fuel efficiency.

Now, being an official moron, I will stay after class and have this explained to me--- in a unified equation. Then we can do the solving for the speed that would yield the maximum fuel-efficiency together. Simple! I have done my job as a student, now write the unified equation on the computer screen and explain it to me.

[GRG55]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

...Drag is one small part of the fuel efficiency equation, but I think (RPM/ mile of travel) and speed (time to travel) are much more important in fuel economy than the drag co-efficient...

...

At highway speed it is parasitic drag that dominates. It is NOT one "small part of the fuel efficiency equation". At those speeds it IS the fuel efficiency equation. That parasitic drag increases as the square of velocity cannot be changed. It is this characteristic of parasitic drag that limits the top speed of motor cars.

My experience in North Dakota was running a friend's rotary powered Mazda RX7 flat out on US52 just south of the border crossing at Portal on our way to Jamestown. Unlike you, we decided to try this in summer...on a dry road. 153 mph indicated was all we could get out of 'er. No idea what the corrected actual speed was, but that little engine could not overcome the drag of the comparatively low-slung and slippery shape of the two-seat sports car [admittedly the car was loaded with gear for an extended road trip [ultimately we logged more than 3000 miles] and was running a bit tail low as a result, which didn't help].

I suggested to my friend that he ditch the rotary and replace it with a small block Corvette LT5 and we rework the suspension [Delron bushings to replace all the rubber suspension mounts, etc.], but he decided to marry his girlfriend, sold the sports car and bought a...gasp...Subaru. Although we never tested the top speed of that new car on a North Dakota highway, I am confident that the parasitic drag increased at the square of velocity for that vehicle too...

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Yes, I believe the drag would limit the top speed possible because drag varies with the square of the speed. But at slow speeds, like under 80 miles per hour, what is the most fuel-efficient speed to drive most cars at?

[GRG55]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Yes, I believe the drag would limit the top speed possible because drag varies with the square of the speed. But at slow speeds, like under 80 miles per hour, what is the most fuel-efficient speed to drive most cars at?

Zero.

Works best if you are not in a ditch in winter btw.

[c1ue]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

My experience in North Dakota was running a friend's rotary powered Mazda RX7 flat out on US52 just south of the border crossing at Portal on our way to Jamestown. Unlike you, we decided to try this in summer...on a dry road. 153 mph indicated was all we could get out of 'er.

I think I'd have been scared to death driving an aluminum can at that speed.

In bringing back my S8 from Florida, I aired it out only once: on an apparently perfectly straight level highway in Arizona.

At 165, when the speedometer was only going up in single digit ticks, an otherwise invisible slight depression and subsequent recovery resulted in a definite 'up' on the wheels sensation.

I decided at that point it wasn't worth trying to see exactly what the top speed could be.

I remember going 160 (top speed) on a Hurricane 1000 motorcycle while both younger and stupider, it is still something I wouldn't want to try again.

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Zero.

Works best if you are not in a ditch in winter btw.

Being in the ditch, I burnt through an entire tank of gas, but drove no-where. So that was the worst possible speed for fuel efficiency. My fuel efficiency was zero.

[GRG55]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

I think I'd have been scared to death driving an aluminum can at that speed.

In bringing back my S8 from Florida, I aired it out only once: on an apparently perfectly straight level highway in Arizona.

At 165, when the speedometer was only going up in single digit ticks, an otherwise invisible slight depression and subsequent recovery resulted in a definite 'up' on the wheels sensation.

I decided at that point it wasn't worth trying to see exactly what the top speed could be.

I remember going 160 (top speed) on a Hurricane 1000 motorcycle while both younger and stupider, it is still something I wouldn't want to try again.

Hence the suggested suspension rework. There's no point in having horsepower that cannot be used if the platform is not stable at speed. And the stock RX7, like almost every high volume production car, is not particularly stable at high speeds. Fortunately the engine gave out, limiting the top speed, before the suspension really got tested.

My early 1970s vintage college-days Nissan gymkhana racer had every single piece of stock rubber in the suspension and steering system mounts replaced with aluminum and Delrin bushings [among other modifications]. On Pirelli CN36's it could out-corner [but not out-accelerate] any Porche of the day.

[thriftyandboringinohio]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

Yes, I believe the drag would limit the top speed possible because drag varies with the square of the speed. But at slow speeds, like under 80 miles per hour, what is the most fuel-efficient speed to drive most cars at?

Light cars and class 8 heavy trucks are different animals for this issue. Typical highway trucks have 12 to 18 speed transmissions, allowing the engine to operate at nearly any rpm you prefer.
This thread started with a focus on the class 8 highway trucks. To answer your questions for a car requires knowing all the details of the engine power curve and gearing of transmission and drive axle. For most modern daily driver cars it's in the 35 mph to 55 mph area.

[Starving Steve]

Re: Hit With $4 Diesel, Companies Impose Speed Controls on Drivers

In our unified equation of drag, rpm, speed, and fuel efficiency, we also need one more thing: the mass of the car or truck. Write all this into one unified equation out-putting the fuel efficiency, and then we can solve for the most fuel efficient speed.

I don't know what a class 8 highway is, but let's assume asphalt pavement in good condition, no snow, no rain, no wind, level ground, no traffic. Let's also assume summer tires, ordinary type, fully inflated.