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Article:Slowing Down Doesn't Always Save Money
We really need to focus on what can make things better. While I totally agree with most of your proposals for improvements, the reduction of speed is not actually a proper solution. This is a bit complex but there are a lot of overhead issues involved that make the time vs mpg issue actually cost energy by slowing things down.
The most serious issue involving mpg is one only our government can solve. This is going too slow! Your vehicle which gets as my Minivan (Nissan Quest) does 35 mpg at 75 mph and has a steady increase from 55 where it gets about 30 mpg drops off its mpg dramatically as I slow it down. At 35mph the minivan gets about 25 mpg. At 25 mph the minivan only gets about 10 mpg. At 15 mph it gets about 5 mpg and at 10 or below this number drops down towards 2 or 3 mpg.
If you have a commute to work and the average speed is 45 mpg you can expect your approximate "City" mileage estimate. The same commute at 25 mpg average gets less than 1/2 of the approximate "City" estimate and at 15 or below your mileage is horrid beyond belief. This is pure power curve stuff and of course varies by vehicle and the number of gears in your gearbox. To be a bit plain here the best thing we could push for is a program to raise the average commute speed in cities by 50%. This would result in about a 25% increase in mpg overall. Since typical commute speeds in most of the country are below 20 mph in much of the country this would not be hard to achieve. Here is how to do it;
- Fix the roads to adapt to traffic. Get rid of timed traffic lights and get good computer light systems.
- Remove as many as possible stop signs and establish controlled intersections.
- Spread arrival times to work out. This isn't rocket science folks.
- Actually fix the roads to handle the traffic.
- Put controls on Interstate and limited access highways entrances where if the traffic slows below a certain rate, nobody gets on until traffic speeds up.
- Raise speed limits in cities in towns by 5 mph or so. Usually this isn't a problem. Obviously there are places this can't be done.
- Tell the cops with radar guns to go find a life. There is good data to show that these guys on our major highways actually cause more wrecks due to slowing traffic down than if they left things alone.
- Encourage the development in congested areas of one way street grids.
- Develop creative solutions to parking problems. (There are a lot of these)
The value of these sort of suggestions includes not fiddling with people's lives and actually making them freer. At the same time it also would save dramatically on energy.
Here is one: Where I live there is a requirement that School Bus routes serve every location 4 times a day (elementary and high school routes). Abolish school bus routes and establish a real regional bus system. It works and it costs less serving more people. It also makes life better for the drivers as they have a full time job.
These just go on and on. I just wanted to point out that it is dubious that we actually save any energy by going 55 vs 75. It varies by vehicle. At the same time I thought I would throw on the table a long list of things that really will do a lot for energy consumption.
People do need to understand that there is no shortage of energy. This situation is completely made up out of the desire of certain very rich persons to make absolutely sure that your freedom is stoppered."
"I am going to try to make this issue of energy saving and speed a bit clearer;
Let’s address the top end of the power curve.
- A lot of modern cars are actually geared as is my Minivan (Nissan Quest 2000 model) for driving about 80 mph. This is the peak of their power curve and gearing. Not all cars are the same. Some cars really do get better mpg at 55. They are a bit rare nowadays.
- Trucks and vehicles that are not aerodynamically really pretty good often start losing mpg about 55mph. Most over the road trucks optimize at about 62mph. It varies some though.
- The difference between 70 and 55 in a vehicle that is not optimized for high speed driving often sees 5% or less difference. It really isn’t much.
Let’s address the bottom end of the power curve.
- No vehicles get any mileage at all stopped. This is one of the reasons hybrid vehicles work. They get to turn off or “Hypermile? automatically when stopped.
- None of the current crop of vehicles gets any mileage worth account while braking.
- Vehicles stopped and then going back to speed have lousy mileage.
- Commutes below 35 mph are below the power curve more than 15% on nearly all cars and trucks. Aerodynamic affects here about null. This is pure power curve.
- Commutes which average a speed like 35 mph are actually normally running about 55 at peak and spending a lot of time stopping and starting.
- Commutes that average below 25 mph are rarely seen above about 45 mph and typically spend large amounts of time stopped.
Now here are the basic realities I was talking about. Speeding up commutes will get drivers to spend less time stopped. They will cause far less acceleration time. They will spend far less time decelerating. As such they will spend far less time getting 2 mpg or 5 mpg and start spending their time getting 21 and 30 mpg and so on. The value of the fixing of a commute here is stunning.
A typical commute in from northern Atlanta into the city center in the morning rush moves at speeds about 10 to 15 mph. Sometimes it gets up to 30 but generally it alternates between stopped and going 30 and all speeds in between. This means that the average car in that commute isn’t getting its “City? estimated mileage. It gets about 5 mpg or 10 mpg. That’s right a 25 mile commute burns something like 5 gallons of gas. ($45! OUCH) Now if this commute ran into town at 35 mph average speed, the cars would be able to burn about 1 gallon of gas on the trip. Read it and weep there is your energy problem. Going too Slow!!!!!! Even if you do better the ratio is still 3:1 or 2:1. It is just a reality that you need to get down the road at the speeds your machine was built to do.
Now lets assume you ran this same mileage going 70 and 55 and the mileage was 5% better at 55. The mileage at 55 is say 30 mpg. We burned 0.830 gallons of gasoline. At 70 we burned 0.875 gallons of gasoline. We saved 0.045 gallons of gasoline a trip. At $5 gasoline you just paid 22.5 cents for the privilege of arriving at work a few minutes earlier and far less fatigued.
Now let’s extract the ratios to speeding up a commute. Even if your mileage only dropped in half, you are looking at doubling your daily gasoline bill for each trip because you went slow going approximately 30 mph max instead of the 55mph max. On a slow day you burn 5 days gasoline instead of one. Can’t anyone see that going slow is the problem.
This is only part of the equation. Your capital costs associated with a car are far more significant than gasoline. Even at $10/gallon these will remain so because they are multiplied on energy costs.
To illustrate: If a company has a salesman who drives 110 miles one way on his route daily at 55 mph he takes 4 hours of his day driving. He works 4 hours. If he speeds up to 75 mph the guy now has 1 more hour to work in the day. He works 5 hours. This may seem insignificant but this is where the rubber meets the road. It is in doing work. For 20% more work, the total cost associated with his commute went up assuming the 5% number claimed, by $5. We are paying this guy to work for 8 hours at $30/hour. We are actually paying him $240 to work 4 hours or $60/hour. If we speed him up we pay him $245 and he works 5 hours or we pay $49/hour. Now which deal would you pick? I pick $49 over $60 every time. This is a no brainer. Commute time is a dead loss. At 55 mph we would for every 5 salesmen at 70 mph have to hire a 6th man just to do the job and buy and maintain a 6th vehicle.
This is why America had such a fit over the 55mph speed limit years ago. Nobody did this math but everybody knew it got in the way of earning a living and living one’s life. Here is a energy multiplier in action. Now that this math should be clear I will tell you a fact about commutes. The prosperity of an area is directly proportional to the average speed of the commute in the area. Why do you think the Japanese like their Bullet Trains, or the French the LTV? Pretty obvious isn’t it. This is why a lot of people commute by aircraft to work. It pays off!
If you want to kill every hope of America digging out of its mess, slow us down. If you want us to afford to survive speed us up! Further, faster, and higher is the rightful goal. It reduces the ratio of energy spent per unit of useful work. (There is your real measuring tool.)
The USA in the 1970’s tried the 55mph speed limit. It killed the economy until it was abolished and then we recovered. Go anywhere you want in the world and commuter average speed will determine the prosperity. Doubling the speed is not linear. The process is exponential. Double the speed does about 4 times the prosperity. Slow it down and well everything dies. This is why the city center of Atlanta is in trouble economically and the outlying suburban area is doing well. If you want prosperity speed the travel up.
A comment or two about hybrid vehicles;
- Hybrids only really work well in two situations at the ends of the power curve. They work quite well at speed and in severe stop and go. In the middle you would do better not to haul around the charging equipment and just drive the wheels.
- Hybrids are at best an interim technology towards an electrical car. This business of bringing your own generator around for an electric car is not practical.
- Overhead costs on Hybrids are pretty severe and most manufacturers are having to subsidy them.
I would like to issue a wish for the best of results for any efforts. I don’t want to discourage any good thing. As a rule of thumb it would be wise to keep in mind that the goal of certain parties in the market is not good. They intend to strip you of your freedom and enslave you to their profit. Don’t volunteer for the chains please. Things like the 55mph speed limit discourage, and distract from the needed changes while allowing government to step in and criminalize us all and steal our money via fines etc. The 55 mph bred severe disrespect for the rule of law and we still suffer the results. A cop running a radar gun is little more than a highway man stealing from passers by. Cloaking it with some lofty sounding goals doesn’t change what it is.
If your vehicle doesn’t do well at higher speeds then don’t drive them. That’s cool with me! But don’t think that it is good for everyone. One size definitely does not fit all.
Some of my proposals for solutions may also have not been understood well. Automatic Driving cars would save 50,000 lives a year, they would save 500,000 hurt people and they would save about 60% of current fuel demand. All for doing the same job we do now. They also would reduce highway construction demand 80%. This alone is a fantastic savings.
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