Drag in car-sized subsonic vehicles is ordinarily treated as proportional to v-squared.

About the most efficient speed for cars was 45 mph last time I checked. Not sure what the rolling friction component is like, so for argument let's just take atmospheric drag. From that, it would appear that an SUV traveling 90 MPH has four times the drag, and thus 1/4 the MPG, of one traveling at 45. Assume I've overestimated the total drag at 90MPH; one might get 1/4 MPG at 100 MPH.

MPG at triple digits of MPH would seem to be single digits. The there's the damage you do to your car driving that fast, and the increased risk if your driving conditions or brakes are bad or your attention wanders, etc. etc.

Not sure it's a clear win, economically. So maybe fast drivers should get gas tax credits? :)

Drag on the second truck in a convoy, however, is far less than that of the lead truck.

Add anti-rear-ending brakes (which actively measure the distance to the vehicle ahead)...

Why would WOC bother to print this?

Nortius,

Your mileage estimates seem off. I'm not knowledgeable enough to explain why, though I suspect non-wind-resistance friction and other factors are a lot bigger than you guess. But in anecdotal terms, having just completed a fairly high-speed trip across Washington state and back in my Suburban, I can confirm that the mileage penalty of ~80mph compared to ~40mph is probably in the range of 20% at most.

On the other hand, I certainly concur with your other point: there weren't any places along I-90, no matter how straight or flat, that I would have wanted to push the speed even higher.

toc (#3), why would you bother to read it?

Had a rear tire blow out at 80 when making the trip from Dallas to Houston one year. (Had to change the tire myself, too... everyone else was in costume! Anime conventions...)

Was not a fun experience. If it had been a front tire, I'd have had a hell of a time keeping it under control long enough to get pulled over. If I'd been going 100, you'd have seen a little story in the news about four idiots getting killed in a rollover...

Possibly also has to do with obstacle avoidance issues. What's the stopping distance at 100 in bad weather? If it exceeds the visibility in bad weather...

Then again, if it's done in Germany, it can be done here too.

If global warming is indeed the ne plus ultra issue of the 21st century, then we should make the following policy changes...

On the other hand, if remediation of global warming is one of many issues that has to be weighed, with costs and benefits balanced against the costs and benefits of other, competing priorities, then...

Well, then there is no obvious, necessary then that must follow, no discussion required. A crash program to substitute nuclear power (current-gen boiling- or pressurized- water reactors) for pulverized coal in electricity generation might or might not be the right course of action. Ditto for 100 MPH travel through urban areas (sorry, on wide-open interstates).

The not-barking dog (per Sherlock Holmes) is that the majority of people who identify Global Warming as society's #1 problem look at ideas such as these, and intuitively recognize that they aren't any good. Perhaps it's not the billed "global warming" per se that is at issue, but the lifestyle of mass consumption and consumerism--which leads to global warming--that advocates find so objectionable. I have some sympathy with this point of view--the carrying capacity of our home planet is, indeed, not infinite. "Our" (First World) economies are indeed outputting vast tonnage of CO2 into the atmosphere; it is imprudent to assume that nothing bad will come of this.

Seen in this light, jet-setting global warmening (per Tim Blair) activists aren't really hypocrites. It's more a problem of false advertising. Inadvertant false advertising for the most part, I suspect: people start off just knowing the right answer, and move fairly quickly to indignation when the sheeple don't follow quickly enough.

Ironically--perhaps--it is the vilified and excommunicated Bjorn Lomberg who was the first to cogently explore global warming as one of a number of serious problems, each competing for attention. And who dared open up Pandora's Box by asking, "well then, how should we rank problems and allocate resouces for their amelioration?"

#5 from Kirk Parker at 8:09 am on Aug 10, 2007

toc (#3), why would you bother to read it?

******************************************

Because my experience with WOC is that hey print intelligent, well thought out articles., not sophomoric ramblings. Hence it is surprising to me that they would waste space publishing this.

In other words, I read the article based upon the usual high quality of the articles published here and had no idea why they would publish this one.

That is not to hard to understand. Is it?

Donald:

I can't seem to open your home blog. I get a WordPress message that says "error establishing a database connection." Hence I'm not sure what your arguments are. It does seem reasanable, however, that if we can coax a top speed of over 80mph from a laminar-flow faired bicycle (Sam Whittingham) it ought to be possible to travel 100 mph or more in an automobile without big penalties in gas mileage. In addition, it's well-known that higher speeds increase the carrying capacity of highways, so would reduce congestion, holding all else equal. There are safety concerns, of course, so it's probably not a leap we could make without some fairly significant design considerations, both for the roadway and the vehicle. Moreover IVHS (Intelligent Vehicle Highway Systems), once installed, will vastly improve the efficiency and safety of high speed travel... but again, not overnight.

Some of our problems are with public acceptance. We could build automobiles that have less wind resistance, but they'd look funny. Automakers probably spend more getting shapes that will sell than they do figuring out why they're aerodynamicly poor.

We could build lighter autos that would be safer. Less steel, less weight, less fuel use. Maybe mostly fill the passenger compartment with impact-resistance foam to reduce the problems when you hit something at high speed. But consumers would have to be taught to enjoy it.

Should we allow current US automobiles to go 100 MPH on our freeways? Maybe a few, but a lot of stretches of freeway would have to be redesigned for it.

So if we could actually make it work, it might be better to have 100 MPH lanes, and have them only for autos that were designed to use them -- new safe fuel-efficient autos. Everybody else should stay out of those lanes. Or maybe stay off the freeways.

"Since even SUVs are many times less polluting than jet liners" It seems to me the question is HOW many times less. How many SUVs going from Dallas to Chicago would be required to get the same # of travelers there as a jet liner?

Cars are currently built to get maximum fuel to speed somewhere between 55-70 mph. Keeping in this range of speed is also where there are most likely to be survivors from a car crash. I beleive that Nader was preety infleuntial in pushing the 'survivor' aspect of speed limits (in addition to pushing seatbelt laws, and car designs that 'crumple' to protect the driver).

Now, since people actively skirt the freeway laws by 10-15mph, would it be safter to just raise the speed limits, and anything above strictly enforced (or would people then just go 10-15mph faster still)?
Or we can go Europe's approach (as I understand it) to have insanely high speed limits, and if you crash, medical costs will be cheap because you're already dead.

I think there are some places where triple-digit might be ok (for example, driving through Arkansas, Texas, Oklahoma on the 40), but near any big city with congestion, that speed could cause some major fatalities.

The 1960's were a fertile time for futuristic speculation into transportation. Passenger trains got put into play in the form of the TurboTrain and Metroliner as a "Back to the Future" answer to highway and airline congestion. Monorails and people movers were the rage. There was even a thing called RRollway, a concept from GATX (the tank car people) to wisk motorists along at 150 MPH in their cars inside an ultra wide gauge tracked car ferry.

Among the 1960's transportation dreams, things having to do with cars and highways were regarded as somewhat obsolete and so 1950's. But there was one concept (did it come out of Cornell?) called Century Expressway.

The idea was a superhighway where cars could be operated safely at 100 MPH (the Century meant the triple-digit speed along with looking ahead to the 21st Century, which was a distant horizon where everyone would wear Spandex suits and look good in them).

There were a number of elements: wider lanes, longer and perhaps more standardized and better marked acceleration and deceleration lanes, electronic traffic control signs indicating speed restrictions for rain or other bad weather. There was some thought that cars had to be specially qualified -- there would be a Century Cruiser that you might rent specially for driving on this highway. There was also a notion of qualifying the drivers, perhaps through special license endorsements or even an automated on-ramp sobriety checkpoint in the form of demonstrating precise driving past some obstacles.

Much of the Century Expressway looks like a current Autobahn -- more stringent driver license certification than in the U.S., electronic speed restriction signs, longer, better marked, and more standardized on ramps.

But there was one big attribute of the Century Expressway proposal: no trucks. The idea was to only run specially-qualified sedans -- I am thinking this would mean no high center-of-gravity SUVs, and certainly no marginally-secured car top loads or trailers.

Of course the 1973 Oil Embargo and the 55 MPH speed limit meant the end of the Century Expressay. But if we were to revive the concept, would people accept the restriction to sedans only, no trucks, SUV's or trailers or external loads?

Err, for those of you not from one of the less populous Western states...we already approach triple digits on the freeways, it's just not legal.

I remember doing a cross country trip earlier this year starting in northern Idaho, across Montana, North Dakota, and over into Minnesota.

Out of urban areas, I had the cruise control set at 95 on a Toyota Camry...and got passed like I was standing still by a minivan driven by the proverbial little old lady a couple hundred miles out of Bismark.

In most of the West, you can drive for hours and not see anything except the occasional semi.

I've always hated the safety/environmental one-size-fits all tyranny of federalism. Where well meaning urbanites tell me how unsafe it is for anyone to drive faster than 65. I immediately get this itch to drop these idiots into the West Texas desert, hundreds of miles from civilization, in a car perfectly capable of doing 90 MPH on a highway capable of doing even better than that, with not a living soul in miles and see how they like it...

Most of the western freeway systems (out of the mountainous zones, where you wouldn't want to go that fast anyway) could handle those speeds easily.

There aren't a lot of airports in these areas either (at least not commercial ones), so driving is pretty much the only option. What makes sense for one area of the country may not make sense for others. Something to keep in mind.

++ to #14. Except the routes that truckers actually use have a lot more than 'the occasional semi'.

If you're on I80 through Wyoming, you're in an endless convoy of trucks that would really benefit from the bare minimum 'convoy-mode' of an autopilot.

While I have don't have an objection to increasing the upper limit, a change to something approaching 100 mph would have to happen gradually for reasons touched on by both Demosophist [3:49 pm on Aug 10, 2007] and Paul Milenkovic [6:33 pm on Aug 10, 2007], that I noticed.

From a liability point of view, I'd have to say only a small subset of interstates sections could be pushed above 75 mph without either redesign or having to post many reduced speed zones.

I have to disagree with the premise that jetliners pollute more than an SUV. I cite the following press release from EasyJet:

Here is the press release:http://www.speednews.com/a/ecojet.jpg/

The money quote:

In easyJet's current configuration and operation, the projection for the eco-liner would generate less than 47g of CO2 per passenger km. In comparison, easyJet's current operations generate 97.5g of CO2 per passenger km, the Toyota Prius emits 104g of CO2 per km; and the European car industry has recently been given a target to achieve 130g of CO2 per km.

It would appear the airliners are one of the least polluting forms of mass transit. Granted the airline figure is per passenger KM, but how often do you see an SUV, or a Prius for that matter, driving down the road with more than one person.

and the easyJet hasn't been built yet . . .

I meant eco-liner.

First we'd need to teach Americans to drive. We drive like cattle, wandering, aimless, oblivious, stopping to eat every few seconds.

You'll get 100 mph speed limits on certain interstate highways. The problem is, you won't be able to drive on them. It will only be legal to enter those highways if your vehicle (typically a freight-hauling semi) is driven automatically, so it communicates constantly with every nearby vehicle and with any important highway features, such as bridges or interchanges.

For the first decade or so, these robot-driven truck will carry human "drivers" just in case, but after that, they will drive autonomously, and will park at terminals where human "harbor pilots" will take them to the loading dock of the final destination. (Of course, Walmart distribution centers will be such terminals, so they won't need human drivers at all.)

Welcome to the future!

#21 Beard:

Such highways already exist. They are called trains.

Fletcher [#22],

I spent some time thinking about that analogy, but left it out of my previous comment. Roads go a lot more places than railway tracks, and there are a lot more opportunities for incremental deployment of automated driving technology.

There are still a bunch of barriers --- technological, regulatory, and economic --- but I would bet on a road-based system rather than a rail-based system, once it starts happening.

I'm not driving on that highway with American drivers.

The solution is investment in public transportation akin to the Japan Railway (JR) system. Fast. On time. Relatively affordable.

We fly on jetliners because the distances are so great. The annointed ones (elites) fly on private jets because they can. The private jet makes sure that they do not have to rub against us lowly rubes who they rightfully rule. I have yet to see a famous person on a Southwest Airlines aircraft 'cept for Herb Kelleher once.

This is very funny. Add to that the rather amusing argument that SUVs may have lower lifetime emission footprints than hybrids, because they last longer, use simpler technology, are cheaper to maintain, are easier to dispose of, and are often made closer to source, and you have a pretty good argument that driving a Hummer is the best environmental statement you could possibly make. As an added bonus, it's got enough chrome that you wouldn't even need a green-poseur sticker.

The problem appears to be getting from here to there.

There is a huge infrastructure investment in highways, particularly in the USA. There is a probably slightly smaller one in airports, and a (now) much smaller one in the railway system. There is a comparitively microscopic one in canals, but remember that where they exist they are important; in fact the Erie Canal was instrumental in the opening up of the West.

There are also considerations of desirable speed of transport. For perishable or time-sensitive goods you need aircraft, or for shorter distances trucks and cars. For goods that aren't quite as urgent, trains. And if it really doesn't matter and/or you have a really big load to shift, canals and/or rivers.

It is quite ridiculous, IMHO, to move such things as coal, iron ore and structural steel on the roads. It usually doesn't matter how long a particular load takes to get there, as long as the supply doesn't dry up; I can quite easily imagine a system where a load of coal en route is considered part of inventory, and stuff is moved according to urgency.

Of course the faster the transport is the larger the carbon footprint is as well, and possibly more importantly the more money eventually ends up in the hands of terrorists.

There is, however, a technology that if developed (and if there is enough money it will be; we already know it works) would cut across quite a lot of these lines. Already tested at about half jetliner speeds, and with far less energy requirement, and that energy being electricity (which you can make in many ways), maglev fits the bill quite well.

For medium-length trips, say 1000 miles or so, and possibly for longer ones, it may well be that a 300mph maglev would be quicker than an aeroplane, if only because the terminals could be much closer to the arrival and departure points. You can't put an airport in Manhattan, but a maglev rail terminus would be easily possible.

It's quite likely that existing rail rights of way would fit in a maglev track alongside with little disruption. Of course, the track has to be built - and that's where the money comes in.

Also, although a maglev crash would be a major incident, it wouldn't be on the scale of 9/11. You can't use a train as a weapon in quite the same way.

I think that the speed limits can be raised at rural long interstaes with 50 miles+ of rural areas at daytime the speed limit should be this:
Long Rural interstaes 100MPH day/80MPH night
Other interstate 80MPH day/70MPH Night
night limit must then be aslo applied under bad weather conditions

the "In easyJet's current configuration and operation, the projection for the eco-liner would generate less than 47g of CO2 per passenger km. In comparison, easyJet's current operations generate 97.5g of CO2 per passenger km, the Toyota Prius emits 104g of CO2 per km; and the European car industry has recently been given a target to achieve 130g of CO2 per km." money quote is a little misleading.
It fails to take into account the wasted fuel before/after takeoff, during taxiing, and during climbout.
As a aircraft mechanic, my professional pride would dearly love to believe that my prfession has the answer, but I know the truth. There are some things that aviation has the answer to, but fuel efficient transport is not among them.

The speed limit of a road segment should be based on its design, topography, proximity to on/off-ramps carrying lower-speed vehicles... It is entirely reasonable to have separate "day" and "night" limits; in some areas a "winter" limit may be a good idea. Where safety permits, let the speed limit hit triple digits. Where it does not, it should not.

Such decisions are inherently local in nature. It is ridiculous to assign a NATIONAL speed limit, and there is no constitutional warrant to do so. With that in mind, the last time Congress didn't directly legislate one; it extorted the States into doing so by threatening to withhold highway funding.

Repeal the 17th Amendment, so we won't have a repeat performance.

There's a blazingly obvious way to do this (speaking as someone who has driven for years on the German Autobahn.) We can do the following things - all at the same time:

1. Improve the average competence level of the American driver.
2. Provide strong market incentives for fuel efficient vehicles.
3. Improve the overall safety of driving on American highways.

How?

By allowing people to drive faster, if...

...they pass a real driving test. Germans go to school to learn how to drive. Think drivers-ed on steroids combined with a written and driving test that make the US ones look like elementary school. (I just went through the OH written and driving test. Didn't even drive on the freeway as part of it!)

...they pay for the privilege. One could make an argument that driving on American roads and highways is a requirement for most people. But driving fast isn't. The additional expense of driving certification should be born by the individual driver.

...they buy an eco-friendly car. Just imagine how many people would want to drive that hybrid, solar, electric or biofuel hot-rod if they could actually drive it at the speeds it's capable of? The CA hybrid HOV lane program was hugely successful. Just imagine if we could extend that sort of incentive to every highway in America?

The mechanics of this are straightforward:

1. Require a specialized license (like they do for RV's, trucks, etc.)

2. Require safety features above and beyond the current standards. For example, forward collision radar is available now on cars, but not widely so. Why not?

3. Require the car be real-world eco-friendly. Don't use existing EPA mileage requirements - develop a new test @ 80mph (or 100mph!) and force the car manufacturers to meet those.

Put the car companies to work building cars people want while saving lives and the planet at the same time!

Andrew

P.s. One other thing that this addresses is a rule of law issue. It simply can't be good for society if on any give day one an stand beside any highway in America and watch 20-30% of drivers intentionally violating the law by speeding!

The law must make an accommodation, because it clearly doesn't conform to the societal norm. For example, tailgating is a much bigger ticket typically than speeding in Europe - because it's the bigger safety risk. That's not the case in America in part because of the speeding ticket as a significant source of municipal revenues...

Excellent non-kneejerk commenters you have here. Good salon. Several have caused me to rethink my opinions on this.

Random comments: Increasing the speed limit means increasing it for all drivers, not just those who would otherwise have flown, so the increased fuel use would be (much?) higher. Andrew's suggestion of fast-driving licensing lessens that, in addition to the other benefits he lists.

The Road More Traveled is an excellent book on the related topics of congestion, light rail, new highway construction.

Trains are good for the situations Fletcher Christian describes, but they are not quite equivalents to high-speed lanes. A train can put a lot of cars on one load, but it is not followed 30 seconds or even 30 minutes later by another string of boxcars. Rail has a lot of non-use time over a 24 hour period. That's not insurmountable, but it's the current reality, and will be unless parallel return lanes are built.

"The there's the damage you do to your car driving that fast, and the increased risk if your driving conditions or brakes are bad or your attention wanders, etc. etc."

Going faster means that you are going to get to your destination quicker provide a shorter window of opportunity for your mind to start wandering. My mind wanders more at the snails pace of 55 mph then it does when I'm going 85.

Driving 100 mph isn't really that harmful to the vehicle. It is the constant heavy braking and acceleration that one must do to sustain that speed when having to dodge in and out of people going 65 that is the cause for increased wear. If everyone goes 100 mph speed then obviously there would be smoother driving and the car should be fine. Cars, engines, drive-trains, and lubricants have advanced considerably in the last decade or so yet we are still stuck with the same speed limits from 30 years ago. Hell, speed limits in the early 60's were often posted at 80-85 with vehicles using 3 speed transmissions and drum braking systems. Vehicles today come equipped with variable valve timing, 5 speed automatics, and multi-piston disc braking systems. Many sedans today post performance stats that rival that of so-called "race cars" from 30 years ago. I saw one article that pitted a Mini-van against a 1984 Ferrari. The Ferrari still won in many categories, but not by much, and in some categories even tied.

The fact of the matter is that most of the posted speed limits are easily 20 mph slower than the recommended safe speeds indicated by the civil engineers who designed a given stretch of road. These recommendations by the engineers are often notated in plans from the '70s so you know they were taking 1970's automobile technology into account when figuring these recommendations. This explains why people generally speed by 10-15 mph because studies show that people generally travel at a rate of speed that is consistent with the given road conditions at the time. Even at post limits of 65 mph when it rains heavily people don't generally say, "Oh, I'm breaking the law by driving to slow." No, they slow down to take into account the reduce visibility and traction. The speed limits are just a recommendation, you always drive according the conditions of the road above all else. In areas that do my some miracle actually have a posted speed limit that matches the engineers recommendation an amazing thing happens. People actually drive the speed limit. So, this hogwash conclusion that people will always automatically drive 10-15 mph above a posted limit is a obvious slippery slope fallacy.

Somehow, this makes sense to people when it allows for going slower then recommended limits but never when we exceed the recommended limits. Around here in Texas you can be in a major interstate, on a road designed for 80 mph and the posted limit will be 65 in many spots. The sheriffs and the constables will be scattered all up and down these stretches, racking up their taxes, err cough fines. Yet, you can pull off those interstates onto a back stretch of farm road and the posted limit will be 55 mph, only 10 miles per hour slower than an interstate. Yet the condition of the road is so poor that one can many times barely navigate 35mph safely. They don't invest the money to fix these parts of the road, they don't post limits that are appropriate for the road conditions. They are too busy racking up fines in the money pit that is the interstate. They say, safety is their major purpose but if that were the cause won't they properly police the most unsafe sections of road? No, they sit at the spots that yield their highest percentage of catching someone. The spots were their is a bend in the road that causes an accident once a month -- nope never there. If they have that nice bridge they can hide behind at the end of a long flat stretch of road -- SPEED TRAP!

To me the biggest thing that stands in the way of sane speed limits is the law enforcement industrial complex. They purposely set regulations that most everyone sees fit to break. They notate how unsafe the roads are simply in light of the fact that there is so much speed. Not whether really the road has some unsafe characteristic. So, they ask for more police to monitor speeds. More police means that they are able to write more tickets. More tickets means more crime and therefore the need for more police. More tickets, more crime, more police and on and on. It is a cash cow and they are not going to let go of it easily.

I don't know what the passenger miles per gallon of a jetliner is, but here are a couple of points of comparison.

I've taken two long road trips this year in my 1995 Toyota Previa. The first one covered about 1400 miles with five people and all our luggage packed around us internally. The second covered about 1200 miles with seven people. All the external luggage was behind the van on a platform supported by the trailer hitch and steadied with straps to the luggage rack on top.

Both trips started in San Diego, and both destinations were many many miles from an airport. They didn't even have long distance bus service.

On the 1400 mile trip, about 15% was twisty turny mountain driving. The 1200 mile trip was nearly all freeway, but climbed from sea level to 9000 ft., then down to 6000.

Cutting past the math to the chase, I got just over 100 passenger miles per gallon on the 1400 mile trip, and barely under 150 passenger miles per gallon on the 1200 mile trip.

We drove at just about the speed limit (65-70 mph) nearly the entire freeway time.

If someone knows how much JP it takes to fly a loaded 737 from San Diego to Sacramento or Red Bluff and back then we can make a comparison.

A related consideration:

On any long road trip, especially with kids, allow an extra 15 minutes per bladder per 250 miles.

The aircraft keeps going while folks hit the latrine. Neither does it stop when someone wants to buy a candy bar.