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5 comments on Integrating Energy, Transportation and Land Use

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crzwdjk on October 4, 2006 - 2:14am Permalink | Subthread | Parent | Comments top
It all depends on how you define "congestion". In the limit case of every house being half a mile away from anything else, with plentiful roads in between, there will be no congestion. You may have to drive 50 miles to the nearest store, but you'll be driving at the speed limit all the way, so that's no congestion. On the other hand, in a dense city, there's almost always some other car in front of yours, so there's 100% congestion, or at least, congestion for 100% of car trips. Even not taking into account the fact that many people will walk or take transit instead of driving, a 15 minute trip in Manhattan counts as congestion, while a 40 minute drive on an empty freeway counts as not congestion, even if both have the equivalent effect of getting you to the nearest mall.
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Valuethinker on October 8, 2006 - 12:38pm Permalink | Subthread | Parent | Comments top
I guess I was defining congestion in the context of an urban area.

The UK experience is if you build a road, it fills up-- it creates its own demand.

Similarly if you expand an urban area, you create flows of traffic to and from that new subdivision, leading to total traffic flow (on existing roads) than was there before-- households in the new subdivision want to work, shop and play in other places besides the new subdivision, and that creates traffic.

Jane Jacobs pointed out the reverse case very well: close a road, and a significant fraction on the traffic in question disappears (I think this happened on the West Side Highway in New York).

I think this all stems from the unique nature of car travel-- it takes up a lot of road space, but doesn't move many people (at 1.1 people per car which I think is the worldwide developed country average).

It's sprawl that creates traffic, rather than density per se.  What happens with density is people make shorter trips and fewer trips by car.

Since people like to live further apart, that seems to be human nature, the trick is to balance the two.

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Valuethinker on October 8, 2006 - 12:40pm Permalink | Subthread | Parent | Comments top
The other thing about car journeys that I recall, and I don't have the exact number to hand, is that something like 90% of car journeys are less than 5 miles ie in a place like the UK, easily doable by bicycle.

I don't know what the comparable US statistic is.

The countries that have tackled traffic congestion (Netherlands, Denmark) have done so by restricting traffic in favour of pedestrians, and aggressively encouraging bicycles.

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crzwdjk on October 8, 2006 - 3:41pm Permalink | Subthread | Parent | Comments top
"It's sprawl that creates traffic, rather than density per se.  What happens with density is people make shorter trips and fewer trips by car."
There you go. That's the more correct version of your statement, with "congestion" replaced by "traffic". Because "traffic" does have the implication of vehicle-miles-travelled, whereas congestion implies travel that is slower than some theoretical maximum.
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