Standardized Gradient for roads - Fuel Economy, Hypermiling, EcoModding News and Forum

thorpie · 03-03-2009, 06:00 AM

Hello
I have written a document briefly outlining the case for standardizing road gradients.
I believe that a standardized road gradient will be the greatest single contributor towards a sustainable transport system. It will permit minimalist vehicles to be manufactured that simply meet a standardized functionality.
I am attempting to promote discussion of this subject. Any comments, or suggestions or assistance in disseminating the content as widely as possible, will be appreciated.

dcb · 03-03-2009, 06:47 AM

My "standard gradient" would be a large sinewave, so I can constantly pulse up and glide down

Oh yah, and all stops would be at, or just after the top, and all drive-throughs would slant forward.

thorpie · 03-03-2009, 08:17 AM

Quote:

My "standard gradient" would be a large sinewave, so I can constantly pulse up and glide down

A sinewave gives a constantly changing gradient which is not optimum. To keep a consistent speed you want one standard down gradient and one standard up gradient!

dcb · 03-03-2009, 08:24 AM

I am using sine wave just as an example. You need to smooth the transitions though, suspension compressions = lost energy.

And I don't think constant speed is necessarily optimal, while ascending sure, but not while coasting.

thorpie · 03-03-2009, 08:47 AM

Quote:

And I don't think constant speed is necessarily optimal, while ascending sure, but not while coasting.

It depends upon whether you can utilize the engine's output most efficiently. Utilize engine only when it is running at minimum BSFC.
Which you can only design to with a standardized gradient up, and a standardized gradient down! (excluding wind!)

dcb · 03-03-2009, 09:03 AM

Well, technically you would need a standardized car too if you are going off of bsfc maps, and a standard rate of ascension, and probably a standardized fuel.

Plus driver (re)training to utilize the new geography. And some assessment of when the money/fuel used to remold the landscape would reach the break even point based on anticipated traffic.

thorpie · 03-03-2009, 09:18 AM

Quote:

Well, technically you would need a standardized car too if you are going off of bsfc maps, and a standard rate of ascension, and probably a standardized fuel.

Exactly. As with any other standardized product, which allows universal interconnection and allows minimalist design to meet only the standard's requirements.
The alternative is to keep requiring over-engineered vehicles to run on over-engineered roads. This equates to allowing builders to use any number of electrical socket types in houses and requiring the manufacturers of electrical equipment to provide a number of different plugs on their products.

robbiewt · 03-03-2009, 09:49 AM

Down hill all the time!

But that's not possible.

Even the slightest climb can hurt gas mileage. It would be very hard to make roads go down hill in both directions. Therefore, a stretched wave would be best for traffic in both directions.

jamesqf · 03-03-2009, 12:10 PM

Seems to me there's already a standard gradient limit on US highways. At least, it's fairly rare to see even a 7% grade on a main highway. The few places I know of that are steeper have major topographic constraints.

CapriRacer · 03-03-2009, 12:40 PM

I am confused by your proposal.

It almost sounds like you are advocating a different grade coming into town than leaving. That can't be right, can it?

While you don't mention a limitation, you must not be discussing mountainous terrain. I know of some roads where it would take 30 miles of approach road building @0.7% just to get to where the road starts up the mountain. Surely you didn't mean that, did you?

You seem to imply a connection between mass production and road building. I am under the impression that roads can not be mass produced - that they are built "in situ", that is, in place. What am I missing here?