From: James Waldby on
On Wed, 19 May 2010 15:09:59 -0400, Les Cargill wrote:
> Ron Peterson wrote:
>> Some cities have a rectangular grid pattern for their streets [...]
>> Other cities, have streets that follow the geography because of
>> mountains, streams, and lakes with some trips being several times as
>> long as a straight line trip.
>>
>> Is there a non-Cartesian grid pattern for a flat community that does
>> better for the worst case than the Cartesian grid pattern?
....
> Better with respect to what? One-way streets tend to lower the "blocking
> factor"/improve the Erlang probability ( % time spent waiting on a light
> ) at some cost in having to loop around.
>
> Pierre l'Enfant had a hybrid design for Washington DC. Still pretty darn
> Cartesian.
[snip link to little picture]
> Road design does not normally optimize for throughput; it optimizes for
> increase in land value. The best tool for managing this is toll roads
> and/or congestion pricing.

Central north Canberra has something of a hexagonal layout ~
<http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Canberra+Australian+Capital+Territory+Australia&sll=37.0625,-95.677068&sspn=42.581364,55.810547&ie=UTF8&hq=&hnear=Canberra+Australian+Capital+Territory,+Australia&ll=-35.281185,149.128375&spn=0.02151,0.049911&t=h&z=15>

On the south side of the lake (click on above map, press page down;
or see <http://en.wikipedia.org/wiki/File:Canberra_SPOT_1088.jpg>) the
layout scheme is based on circles. (The lake, which was filled with
water in 1964, is named after Walter B. Griffin, who won the 1911 Canberra
design competition.)

--
jiw
From: Les Cargill on
Mike Terry wrote:
> "Les Cargill"<lcargill(a)cfl.rr.com> wrote in message
> news:4bf449c8$0$15824$9a6e19ea(a)unlimited.newshosting.com...
>> alexy wrote:
>>> Les Cargill<lcargill(a)cfl.rr.com> wrote:
>>>
>>>> Is this because the worst-case is SQRT(2) for running the sides
>>>> of an equilateral right triangle
>>>
>>> Times, they are a-changing. They hadn't even invented equilateral
>>> right triangles when I was in eighth grade! ;-)
>>
>> Doh! Isosceles, then - 45/45/90 being the angles in units of degress.
>>
>
> You can have an equilateral right triangle on a spherical surface - I expect
> that's what you meant :-)

Uh... yeah, yeah, that's it ":)


>
>> --
>> Les Cargill
>
>

--
Les Cargill
From: Tim Little on
On 2010-05-19, alexy <nospam(a)asbry.net> wrote:
> Well, if you want to go 1 mile east, I agree that after traveling on a
> 60-degree road for 1.155 miles,

You wouldn't do that. You would travel along bearing 60 for 0.577
miles, then along bearing 120 for 0.577 miles.


- Tim
From: Pubkeybreaker on
On May 19, 10:44 am, Ron Peterson <r...(a)shell.core.com> wrote:
> Some cities have a rectangular grid pattern for their streets and in
> the worst case, trips can be 40% longer than a straight line trip.
> Other cities, have streets that follow the geography because of
> mountains, streams, and lakes with some trips being several times as
> long as a straight line trip.
>
> Is there a non-Cartesian grid pattern for a flat community that does
> better for the worst case than the Cartesian grid pattern?

Yes. Look up "Steiner Tree"
From: Ron Peterson on
On May 20, 7:44 am, Pubkeybreaker <pubkeybrea...(a)aol.com> wrote:
> On May 19, 10:44 am, Ron Peterson <r...(a)shell.core.com> wrote:

> > Is there a non-Cartesian grid pattern for a flat community that does
> > better for the worst case than the Cartesian grid pattern?

> Yes.  Look up "Steiner Tree"

Thanks, that gives me another way to look at the road design problem.

--
Ron