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thorpie 03-03-2009 06:00 AM

Standardized Gradient for roads
 
1 Attachment(s)
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

1 Attachment(s)
Down hill all the time!
http://ecomodder.com/forum/attachmen...1&d=1236091405
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
 
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?

thorpie 03-03-2009 04:28 PM

Quote:

It almost sounds like you are advocating a different grade coming into town than leaving. That can't be right, can it?
There are two gradients. For the bulk of travel it is downhill at 0.7%. The uphill elevation shift gradient, while not "standardized" at this time, will be considerably steeper than the 0.7% downhill. If the uphill is 7% then 91% of travel will be on the 0.7% gradient and only 9% on the uphill elevation shift. At this time the uphill gradient is undefined because it needs to cater for a variety of different engine powers.
Because town centres are most often besides water, which is at the low point of surrounding areas, then coming into town the terrain will often naturally provide a 0.7% downhill gradient with no uphill elevation shifts. In these cases travelling out of town will require double the elevation shift, so only 82% of travel will be on 0.7% downhill while 18% will be on 7% uphill.
Quote:

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?
This is 30 miles of downhill assistance that is currently not utilized. 30 miles @ 0.7% is 1,100 ft. Travelling towards the mountain would be 3 miles of elevation shift @ 7% for the 1,100 ft elevation increase plus a further 2.7 miles for the elevation shift to provide for 0.7% travel on the bulk. So there would be 5.7 miles @ 7% uphill & 24.3 miles @ 0.7% downhill.
Quote:

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?
Here you have hit the crux. I am precisely saying that for long term it is better to mass produce the roads and infrastructure to a standardized form. Long term being what we leave our kids and grandkids. Leaving our kids the current non-standardized road network, which we value at so many trillions of dollars, is likely to be worth nothing to them. Zilch! Here you go kids, we leave you a hindrance, the 20th century folly.

dcb 03-03-2009 05:03 PM

It's hard to say if we would even recognize what passes for a road if offered a glimpse of two generations from now, let alone a car.

A road could be a lot more "rail" like, and a car driven by an electric motor does not see the same benefits of engine off coasting that an internal combustion engine does. But if ICE's are part of the target, my guess is that it is a mid-term target at best, and would need a sufficient downgrade to maintain speed without any power, to reclaim maximum benefit (and certain states would have to repeal 80 year old anti coasting laws), roller coaster style :)

Frank Lee 03-03-2009 05:21 PM

Sounds like you're talking about moving MOUNTAINS of fill and having some nasty ditches besides.

thorpie 03-03-2009 05:28 PM

Quote:

A road could be a lot more "rail" like
This is what is needed for longer distance, moderate speed transport. For a number of years I have been struggling with how do you get small, minimalist vehicles to en-train and de-train at speed?

thorpie 03-03-2009 05:31 PM

Quote:

Sounds like you're talking about moving MOUNTAINS of fill and having some nasty ditches besides.
Much less than modern highways.

Bicycle Bob 03-03-2009 05:36 PM

I don't think the areas suitable for this treatment are enough to create a standard for the rest of the planet. Out here, it's gently rolling hills and maybe a hundred vehicles a day. We are lucky to get a moderately uniform surface.
I put in a proposal for a planned community on a hillside once. I recommended that all roads angle up-slope to either left or right, at about 2% grade. This would produce rhomboid grid sections. Going straight up the slope would be a T-bar powered by a stream coming down. Anyone on a bicycle could leave anywhere in town, coast down toward a T-bar, ride it up, and then coast down to any other destination.

Bicycle Bob 03-03-2009 05:53 PM

Casual Car Trains
 
Quote:

Originally Posted by thorpie (Post 90635)
This is what is needed for longer distance, moderate speed transport. For a number of years I have been struggling with how do you get small, minimalist vehicles to en-train and de-train at speed?

Now that one has a lot of potential, IMHO.
How about having, as an express lane, light rails set in like tram tracks. You'd pull onto the motorway and get up to moderate speed. When a "train" passes in the express lane, you accelerate, move in behind, and catch up. As you touch bumpers, your rubber tires go into low-rider mode and you sink onto steel wheels as your bumper couples with the car ahead. Some others latch on behind.
Approaching the next exit, you see the car ahead rise and unlatch. If you are asleep, he brakes and accelerates, or you brake a touch and he slides over. Then you can move up and close the gap, or, if it was a popular exit, become the new lead car.
We'd need standardized hitches, bumpers, steel wheel assemblies, and instruments to keep everyone contributing, but it should be a lot smoother and safer than many current flows.

dremd 03-03-2009 06:18 PM

Quote:

Originally Posted by thorpie (Post 90513)
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!

I disagree.

At the earliest part of the glide you would have minimal grade (no need to speed up), then at the bottom you would throw a good bit of potential in to kinetic as to get up the next hill.

I have often wondered while in other parts of the country where the break even point is with moving mountains, I am certainly no expert, but If I had to guess, the interstate highway system already leans to the side of moving mountains, where as local roads, go with the land.

I do see your point, I just don't believe it is feasible at this point of development

Frank Lee 03-03-2009 06:48 PM

Quote:

Originally Posted by thorpie (Post 90637)
Much less than modern highways.

How can that be? :confused:

jamesqf 03-03-2009 11:08 PM

Quote:

Originally Posted by thorpie (Post 90615)
There are two gradients. For the bulk of travel it is downhill at 0.7%. The uphill elevation shift gradient, while not "standardized" at this time, will be considerably steeper than the 0.7% downhill.

Something tells me you haven't quite thought this through :-) Take an example: there's a road I drive frequently, about 17 miles between place A down in the valley and place B at the top of a mountain, with an elevation change of about 4400 ft. So you're going to build two completely different roads, one for downhill and the other for uphill, and (using your 30 miles at 0.7% = 1100 ft, which I haven't checked) the downhill road is going to be 120 miles long.

Now suppose you happen to live halfway up the hill, or want to visit a place (e.g. the local ski area) that's partway up. You either have to waste a lot of time going one way in order to go the other, or have to build a lot of connector roads between the up & down routes.

thorpie 03-04-2009 03:52 PM

Quote:

Something tells me you haven't quite thought this through :-) Take an example: there's a road I drive frequently, about 17 miles between place A down in the valley and place B at the top of a mountain, with an elevation change of about 4400 ft. So you're going to build two completely different roads, one for downhill and the other for uphill, and (using your 30 miles at 0.7% = 1100 ft, which I haven't checked) the downhill road is going to be 120 miles long.
Now suppose you happen to live halfway up the hill, or want to visit a place (e.g. the local ski area) that's partway up. You either have to waste a lot of time going one way in order to go the other, or have to build a lot of connector roads between the up & down routes.
Large downward elevation shifts are not precluded, it is never worthwhile traveling additional distance on lesser downward gradients to get to a lower point.
When large downward elevation shifts are undertaken most advantage from the 0.7% gradient will be lost, the energy stored as height will be lost through braking rather than assisting in traveling.
These substantial downward elevation shifts are not typical. Glasgow is a hilly city, of the 20 cities I have looked at it is the hilliest. Within 20 km it does rise to 400 metres to the north and 300 metres to the south, Traveling in from both of these locations would require substantial downward elevation changes.
However this is not typical. About 1/2 of the circumference of a 20 km radius circle from the Glasgow's centre is below the 140 metre elevation required to give a 0.7% gradient. Major inbound feeder roads could use this terrain effectively to provide a 0.7% gradient from 20 km out.
Here is a Google Earth Overlay showing the gradients from locations in the Glasgow region to the city centre
If anyone would like Google Earth gradient overlays for any other cities I can produce them simply, just add a post.

jamesqf 03-04-2009 05:08 PM

Oh, you're thinking about UK roads :-) There I agree that something could be done about the gradients on some of them. I remember pedaling up a couple of examples in Yorkshire, where the route planning was seemingly done by sheep, if not mountain goats. And the road between Windemere and Ullswater... I though my legs were going to fall off.


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