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The Irresistible Urge to Build Cities from Scratch

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Re: The Irresistible Urge to Build Cities from Scratch

#71

Post by gowld »

eesmith wrote: post #22
danaris wrote: post #15

Earlier quoted context omitted.

I've...never seen a roundabout with lights. Granted, the state I live in doesn't do them much, but I've visited places (like MA) that do them a lot, and they're all very much like European roundabouts, just with inferior signage.

Here's a rotary in Boston (Sullivan Square) with a traffic light - https://www.google.com/maps/@42.3840002,-71.0744129,3a,75y,9... . Here's a roundabout in Cape Town (Adderley Street Fountain) with a traffic light - https://www.google.com/maps/@-33.9202591,18.4250697,3a,75y,4... . Here's one in Cambridge, UK - https://www.google.com/maps/@52.2084812,0.136931,3a,75y,82h,... .

The first 2 are lights near the roundabout (where streets cross, or at pedestrian crossings), not in at the roundabout.

Re: The Irresistible Urge to Build Cities from Scratch

#73

Post by jpatokal »

jermaustin1 wrote: post #52
RightMillennial wrote: post #43

Earlier quoted context omitted.

No one uses turn signals on them, and you never know when, where, or if someone is going to turn. It's haphazard maneuvering. 4-way stops are far more predictable and functional.

Your first comment is accurate, no one uses turn signals in any of the ones I use on a daily basis either, but that doesn't make them inefficient. In fact I think it keeps everyone on the defensive, and makes them pay more attention before entering. But as I said in an earlier comment, the reason they kind of suck in the US is we don't seem to do them right. * A very wide circle (350ft/100m minimum) with 3 lanes * Ea…

Huh? That's only feasible for intersections of large roads, but American four-way stops are usually on small(ish) residential roads, where single-lane roundabouts work just fine.

Re: The Irresistible Urge to Build Cities from Scratch

#74

Post by bobthepanda »

burfog wrote: post #62
cimmanom wrote: post #56

Earlier quoted context omitted.

That doesn't compute for me - at least not in an urban environment. You're safest on the street where there are the most people; and criminals aren't going to try to break into a building if there's an audience. High foot traffic leads to safe cities. Cul-de-sacs discourage foot traffic.

That is a 100% urban mindset. I can't even imagine thinking that way. Other people find urban areas terrifying because each person present increases the threat. Crowds mean pickpockets and sometimes riots. Every person must be watched, and this is incredibly stressful. It's constant preparation for a fight-or-flight response. The non-urban mindset feels much safer with completely empty streets. The next best thing wo…

Conversely, if someone mugs you in the cul-de-sac and no one is there to hear you scream, are you really safe? How can you get help? There may be people driving by, but they probably only hear whatever's going on for a split second as they drive past you in a sealed car.

There are crowds everywhere there is economic activity. No one thinks the shopping mall or the beach or the park is the next coming of the Bolsheviks or the next Ferguson; that's all purely suburban American hysteria.

Re: The Irresistible Urge to Build Cities from Scratch

#75

Post by eesmith »

burfog wrote: post #62
cimmanom wrote: post #56

Earlier quoted context omitted.

That doesn't compute for me - at least not in an urban environment. You're safest on the street where there are the most people; and criminals aren't going to try to break into a building if there's an audience. High foot traffic leads to safe cities. Cul-de-sacs discourage foot traffic.

That is a 100% urban mindset. I can't even imagine thinking that way. Other people find urban areas terrifying because each person present increases the threat. Crowds mean pickpockets and sometimes riots. Every person must be watched, and this is incredibly stressful. It's constant preparation for a fight-or-flight response. The non-urban mindset feels much safer with completely empty streets. The next best thing wo…

Please define "urban".

Cul-de-sac layouts are usually in suburban regions. Is that included in 'urban'? Or are you comparing urban cores to exurbs or rural regions?

I've walked outside at 1am in a city with no one else on the streets. I've walked at 1am in another city with a lot of people on the streets. I can tell you that I felt safer when there were more people on the street than just me. Which would make you feel safer?

FWIW, "high foot traffic" does not only mean "crowds". Neighbors walking by every few minutes would count as high traffic.

To give more concrete numbers, https://spacesyntax.com/wp-content/uploads/2011/11/Hillier-S... concerns this exact topic. The author writes "Mean pedestrian movement [for road] segments without retail the rate is 158.476 [per hour] for 317 segments", where a 'segment' is the section of street between intersections, in this case, in London.

That's roughly 2-4 people on the street at any one time - hardly a crowd that would lead to a riot!

On streets with retail, it's 640, or about 10-20 people at any one time.

Re: The Irresistible Urge to Build Cities from Scratch

#76

Post by eesmith »

gowld wrote: post #71
eesmith wrote: post #22

Earlier quoted context omitted.

Here's a rotary in Boston (Sullivan Square) with a traffic light - https://www.google.com/maps/@42.3840002,-71.0744129,3a,75y,9... . Here's a roundabout in Cape Town (Adderley Street Fountain) with a traffic light - https://www.google.com/maps/@-33.9202591,18.4250697,3a,75y,4... . Here's one in Cambridge, UK - https://www.google.com/maps/@52.2084812,0.136931,3a,75y,82h,... .

The first 2 are lights near the roundabout (where streets cross, or at pedestrian crossings), not in at the roundabout.

Okay, next roundabout over in Cape Town, no crossing street, no pedestrian crossing - https://www.google.com/maps/@-33.9172315,18.4285489,3a,75y,1... .

Re: The Irresistible Urge to Build Cities from Scratch

#77

Post by HarryHirsch »

jdmichal wrote: post #55
jermaustin1 wrote: post #21

Earlier quoted context omitted.

I think that the size of the round about matters. The larger it is, the more opportunity a driver has to get to an internal lane and not destroy on-ramping from other directions. Also the timidness of drivers to enter a circle kills the flow and causes a backup that takes time to clear. I hit 4 different traffic circles on my 40 mile trip home, two of them are 1 lane wide and only about 100 feet wide, the other two a…

Then there's roundabouts that look like this: https://www.google.com/maps/@27.9775503,-82.8273026,101m/dat... Multiple two-lane entrances. An inner lane that goes all the way around but cannot exit. An outer lane that has a single break between the incoming and outgoing sides of the same road. Oh, and cherry on the sundae, it's in a tourist-heavy area, so many drivers have little-to-no familiarity with it. People blo…

Look harmless. From the description you'd have thought this was the Magic Roundabout in Swindon!

It just reinforces the prejudice that Americans can't drive.

Re: The Irresistible Urge to Build Cities from Scratch

#78

Post by HarryHirsch »

eesmith wrote: post #22
danaris wrote: post #15

Earlier quoted context omitted.

I've...never seen a roundabout with lights. Granted, the state I live in doesn't do them much, but I've visited places (like MA) that do them a lot, and they're all very much like European roundabouts, just with inferior signage.

Here's a rotary in Boston (Sullivan Square) with a traffic light - https://www.google.com/maps/@42.3840002,-71.0744129,3a,75y,9... . Here's a roundabout in Cape Town (Adderley Street Fountain) with a traffic light - https://www.google.com/maps/@-33.9202591,18.4250697,3a,75y,4... . Here's one in Cambridge, UK - https://www.google.com/maps/@52.2084812,0.136931,3a,75y,82h,... .

You find that model in areas which in peaktime see too much traffic for a roundabout to work well. If traffic along one pair of roads is too heavy anyone on the minor roads can't get in. So the light serves to gate the heaviest traffic. During off-peak hours the light is off.

Re: The Irresistible Urge to Build Cities from Scratch

#79

Post by rayiner »

JoeAltmaier wrote: post #14
rayiner wrote: post #13

Earlier quoted context omitted.

Diagonals can be okay used sparingly, but roundabouts destroy traffic flow the way Americans do them (with lights).

We don't do them that way. In my area, roundabouts are put in where traffic occasionally bursts from one direction, and where traffic levels are low. Because they quit working once traffic increases, because it can be impossible to get on if there's continuous flow from another direction. Maybe the lights reported are because the roundabout has outlived its usefulness? A stopgap before ripping it out.

> Maybe the lights reported are because the roundabout has outlived its usefulness? A stopgap before ripping it out.

Yes, the roundabouts here in D.C. long ago outlived their usefulness. Unfortunately, ripping them out probably isn't in the cards.

Re: The Irresistible Urge to Build Cities from Scratch

#80

Post by rayiner »

danaris wrote: post #15
rayiner wrote: post #13

Earlier quoted context omitted.

Diagonals can be okay used sparingly, but roundabouts destroy traffic flow the way Americans do them (with lights).

I've...never seen a roundabout with lights. Granted, the state I live in doesn't do them much, but I've visited places (like MA) that do them a lot, and they're all very much like European roundabouts, just with inferior signage.

Every roundabout in D.C. has lights: https://www.google.com/maps/@38.9020548,-77.0505595,3a,75y,8....

Some have through streets with lights mixed in with the circle: https://ggwash.org/images/posts/201611-221233-1.png.

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