Heavy vehicles can safely go the same 70mph (or 75 out west) as cars and it's much safer to have all vehicles on an interstate going the same speed.

Also, trucking companies pay drivers by the mile and cutting their speed limit by 20 percent would cut their wages accordingly. You personally may not like semis on the road, but pretty much everything you own was carried on a truck once. "If you got it, a truck brought it". Everything we buy would cost more.

As for doubling fines, I'm just so anti-taxation that I can't understand why whenever someone here wants to punish a particular group, they think the government should profit from it.

Also, I don't know the GVWR for any of the vehicles I own, but I'm pretty sure that fully loaded, even a 4-cyl 4-seat car (like I drive) might top 4K lbs.

I'm in favor of small cars and saving gas, but in the end, we're going to burn all of it anyway. So this way we'll burn it faster. Just means that we'll get to electric cars more quickly. Saving 20% just prolongs it another five years. In the 1800's when whale-oil became nearly-unavailble for lighting, kerosene almost completely replaced it in something like five years. That'll happen with gas too.

FYI I logged over a million miles in tractor-trailers before I got completely fed up with the total corruptness of the entire transportation industry, from the drafting of transportation laws to the enforcing of those laws to the insane pressures put on overworked, underpaid drivers to meet demanding schedules. 40 hours of work per week is the norm in just about every other industry, but for an OTR driver, 70, 80, or even 100 hours of work are not unusual.

Log books? Oh, please, grow up. If every truck driver logged exactly the miles driven and the hours actually worked, the entire system would collapse within a month (drivers are paid by the "Household Movers Guide," which shows mileage between cities, not within the city limits, and shows the most direct route, whether or not the route is legal: for example, it does not reflect bridge weight restrictions or underpass limits).

Corrupt. Drivers are consistently cheated on mileage.

Dual speed limits are the norm throughout the world, and reducing speed, especially for heavy vehicles, dramatically improves safety, as well as saving fuel.

The best way to improve truck safety is to lighten the burden placed on drivers, increase their pay, put reasonable, enforceable limits on "hours of service," and make sensible limits on how they are exploited by unscrupulous customers and employers.

My present "beater, a 1992 Buick Century, has a curb (empty) weight of right around 3,000 lbs, and a payload capacity of around 900 lbs, so within the 4,000 lb GVWR (my Pontiac Trans Sport has a higher curb weight and a much higher payload capacity, thus a much higher GVWR). Most small-to-medium cars, and a few compact SUVs, fit under the 4,000 lb GVWR limit (I did not arrive at the 4,000 lb limit arbitrarily).

Key to this concept is stricter enforcement of speed limits (which, alone, without the dual speed limit, would conserve quite a lot of fuel). Think of it as a voluntary tax- if you don't want to pay the tax, you don't have to, just don't exceed the speed limit. The main purpose of the dual speed limit is to discourage consumers buying oversized vehicles for the sake of fashion, but to allow for their use for legitamate purposes, like for the jobs they were actually designed to do.

I'm glad that my defense of truck-driving (which I know very little about) wasn't needed for you. I'm sorry to hear that the industry is in such straits.

As for safety, of course slower is safer, but I don't think you've addressed the difficulty of vehicles going different speeds causing accidents. I think there's plenty of evidence that this is a factor in causation of accidents.

As for stricter speed enforcement and higher fines, I'm not a huge fan of speed-limits at all. Apparently the Germans and Italians do fine without them. We have a lot bigger country, too. The main argument for them at all is the thing about similar vehicle speeds being safer.

You're probably right on the 4K lbs being enough.

Finally, as for discouraging big vehicles, I think another factor people don't consider is that only 'richer' people actually buy new vehicles--I'm well employed and own many cars, but I don't and won't buy them new. It's usually a waste of money to buy new, when you can buy a good older car that's half the price. That means that new car retailers have to appeal to people that are used to wasting money. This is part of why SUV's have sold so well in the USA. So when less-rich people want a car later, the used market is full of wasteful cars that appealed to people that didn't care about the cost of the car or the gas.

Looks like you've got some archaic laws in the USA, most countries have lower speed limits for heavy vehicles, see the table here.
Within the EU it is also compulsory to fit Tachographs to all commercial vehicles, and speed limiters as well. The Tachographs are used both to check speed limits have not been exceeded, and to check drivers' maximum working hours. The police do check the Tachographs regularly, and enforce maximum working hour limits. See here and here.

ChrisF, I don't know why you think faster equals archaic?

In my picture of 'the future,' a century from now, vehicles will drive 200kph+, not slower than now.

There are great sections of the US where you can drive without seeing so-much as a house for a many minutes. I don't see value for Any vehicles to be limited in speed in these areas. Your Wiki chart shows Australia limited to 100kph, but I've heard the road-trains cross the country at 150? Not true?

Yes, all of our trucks record speed here too, but I think the paper-wheels are mostly gone. But the speed record is not for the police, it's for the operator/owner.

I still don't understand how having a whole line of fast cars having to negotiate around a convoy of slow-trucks can be safe. Especially on a two-lane. In my state, the speed limits are the same and I like it. Other states do have dual speed limits, but it seems to just cause bottlenecks.

Mind saying what country you're from?

hrench,
FYI I'm British, but currently living in Switzerland, having been to a few other places as well.
In my picture of the present, there are already ground vehicles doing 200 kph+, even 300kph+, and I've been on them. Its just that they are on segregated tracks, with automatic steering and braking, and not powered by fossil fuels (at last directly).

This post started about imposing speed limits on heavy vehicles as a fuel conservation measure, which could be accomplished much easier by just putting up fuel prices.

It then diverted into considering speeds and working hours for commercial vehicles, and I was trying to point out that in other countries these are already strictly limited on safety grounds and enforced, you don't want to fly with a tired pilot, so why would you want to cross the path of an oncoming heavy vehicle driven by a tired driver. Heavy vehicles have longer stopping distances, and do more damage, so that is the rational for lower speed limits.

It's not true that the Germans and Italians don't have speed limits. There are parts of the German Autobahn network that are do not have speed limits, but only parts. Speed limits apply to heavy vehicles at all times, and retarders fitted.

I wouldn't suggest dual speed limits on two-lane roads.

If you look around, I think you'll find that most two-lane roads in the US have a single speed limit for all vehicles (usually 55 mph), and it's usually a bit less than the speed limits on the "big roads," the 4-lane divided highways (typically, 65-70 mph for cars, 60-65 mph for trucks).

I've spent many hundreds of hours driving two-lane roads at night, following behind a long line of other large trucks, and usually within 2 or 3 mph of the posted speed limit (usually 55 mph or less); invariably, we'll be passed by "four-wheelers" travelling several mph over the limit (typically, 65-70 mph, in the rain, seriously reduced visibility, with icing conditions imminent). I don't think that situation would be any safer with all those trucks speeding, too.

ChrisF, the idea of using a TGV to get to work seems like overkill. I live in a rural area and travel 34 miles to work. My 30 miles would go more quickly (and be more fun) if I could do them at 200 kph, but I don't think they'll build a TGV in my state ever. There just aren't enough people. But I could drive at that speed in a car.

Watching my favorite British show "Top Gear", I didn't think any of the EU countries had speed limits (humor).

Beaugrand, if you mean for your dual speed limit to only apply to four-lane, I still think it's inconvienient for my 120 mph future-kabinscooter to have to pass all of those 60mph semis. Actually, its scary now to pass them in my Capri.

In Kansas, we have 'super-two' highways that are 65mph (we drive 70) and have an occassional slow-lane for lines of cars to pass slower ones. We don't have dual speed limits. I can't remember the last time I saw a large truck wreck on a highway. Truck drivers are often the best drivers.

If you agree with energy guru Jan Lundberg ("The Lundberg Letter"), the long-haul trucking industry will be gone by the middle of the century. Their business will go back to the railroads, which are 3 times more fuel-efficient, and much safer.

He predicts the same for the airline industry.

Actually, the idea is to have all those 10 mpg SUVs stuck in the slow lane with the big trucks, while the Cabin Scooters whizz past in the fast lane.

Apparently, this subject has been studied, according to Wiki, "A 1987 study finds that crash involvement significantly increases when trucks drive much slower than passenger vehicles,[77] suggesting that the difference in speed between passenger vehicles and slower trucks could cause crashes that otherwise may not happen. Furthermore, in a review of available research, the Transportation Research Board, part of the United States National Research Council, states "[no] conclusive evidence could be found to support or reject the use of differential speed limits for passenger cars and heavy trucks"

I don't think there is a national speed limit of 70mph. In Texas, we have speed limit signs that say 80mph in the desert on the way to El Paso.

There's no way that if I'm driving my truck and trailer on my way to the race track with a race car on the back, that I'm going to go under 55mph! HA!

What is better for the economy? If it helps the economy, it helps our standard of living. If it doesn't, then it hurts our standard of living. While mpg go down as speed goes up, there are trade offs. For example, time is money. People's time costs money. Also, if I could drive to Florida doing 140mph +, I wouldn't have to worry about wasting any money by stopping overnight in a hotel.