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From: James Waldby on 19 May 2010 19:02 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 19 May 2010 21:06 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 20 May 2010 05:41 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 20 May 2010 08:44 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 20 May 2010 09:39
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 |