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It is nice when they throw in some diagonals and roundabouts for variety. Gives you more options when moving across the city.
by provolone 8y ago
It is nice when they throw in some diagonals and roundabouts for variety. Gives you more options when moving across the city.
- rayiner 8y agoDiagonals can be okay used sparingly, but roundabouts destroy traffic flow the way Americans do them (with lights).
- JoeAltmaier 8y agoWe 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.
- umichguy 8y agoHorses for courses....roundabouts are great for low to medium traffic conditions. Sometimes the lights are there for times of the day when the traffic is heavy. The lights go out when traffic calms down.
- jermaustin1 8y agoI 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 are a lot larger and have 2-3 lanes. The narrow ones [1] back up much quicker during rush hour(s) especially when you have non-commuters using them (you can tell who they are). The one that is 3 lanes wide [2] usually has a protected lane for only going to the first exit (on then off), then a middle lane that circles the entire roundabout and a middle lane that allows you to exit at any of the exits whenever you want. It works very well. I have never seen a backup on it. The one that is only two lanes [3] backs up quite a bit during rush hour, when there is a West Point football game or because someone is too scared to enter. The backup clears relatively quickly, but I feel it wouldn't back up at all if there was protected on-ramp. 1: https://www.google.com/maps/@41.324487,-73.8829004,106m/data=!3m1!1e3 https://www.google.com/maps/@41.324487,-73.8829004,106m/data... 2: https://www.google.com/maps/@41.2981376,-73.935245,212m/data=!3m1!1e3 https://www.google.com/maps/@41.2981376,-73.935245,212m/data... 3: https://www.google.com/maps/@41.3202891,-73.9909974,212m/data=!3m1!1e3 https://www.google.com/maps/@41.3202891,-73.9909974,212m/dat...
- jackpeterfletch 8y agoIn countries where they're common place and part of the licensing curriculum, roundabouts are far superior for throughput and traffic flow than any other kind of intersection of comparable size. To get any further improvement you start having to look at junctions with over head ramps and tunnels.
- jermaustin1 8y agoI think because the US only just started adding them, and various other intersection experiments, it will take us some time to become fully comfortable with them. My wife's family comes from a small town outside of a small town in Louisiana and I remember when they opened the traffic circle there [1], the entire town hated it because they had never in their lives had such bad traffic, because no one knew how to use a yield sign -- stop meant stop, no sign meant yield, but now there is a new triangular stop sign, what the hell man. Now days though, it flows amazingly, but it took close to a decade. I'm sure it will still improve over time, but now that the entire population has used it, they get it. 1: https://www.google.com/maps/@31.1609199,-93.267374,121m/data=!3m1!1e3 https://www.google.com/maps/@31.1609199,-93.267374,121m/data...
- michaelbuckbee 8y agoWhat you're describing is my experience with them as well. My parent's town in Ohio added one [1] and there was an uproar, but it's worked surprisingly well. It replaced a very dangerous 4 way stop/traffic light intersection that very regularly saw accidents due to the geography (hilly) and the road layout (straight into the intersection after a mile of rural road). 1 - https://goo.gl/maps/NmyMpNEqn8A2 https://goo.gl/maps/NmyMpNEqn8A2
- jdmichal 8y agoThen there's roundabouts that look like this: https://www.google.com/maps/@27.9775503,-82.8273026,101m/data=!3m1!1e3 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 block the outer lane waiting to move inside when the outer lane disappears. And then block the inner lane waiting to go through the outer lane to exit. Not all of this is on the drivers...
- rayiner 8y ago> 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.
- provolone 8y agoCompare Dupont Circle to Connecticut & K st. Down at K & Conn. they need to use at least 5 traffic officers to direct the flow during peak times. Meanwhile Dupont circle handles P street, 19th street, Connecticut avenue, Massachusetts avenue, and New Hampshire avenue. Plus there is the pedestrian traffic from the park and the metro stop at Dupont. Can you imagine doing that with only traffic lights? How many officers would be required to massage that mess? Unless you propose building a spaghetti mixer, I can't imagine a better system for drivers or pedestrians.
- rayiner 8y agoNew York and Chicago manage to handle streets just as busy with regular 4-way intersections. The problem with any K street intersection is the bizarre access roads on each side that confuse drivers to ill effect.
- danaris 8y agoI'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.
- village-idiot 8y agoWe have a few roundabouts in my town in SoCal, small ones, and they all have stop signs.
- umichguy 8y agoThat's kind of stupid...takes the point away from roundabouts. They're designed to keep the traffic flowing in low /medium conditions when a traffic light or stop sign would bring it to a halt otherwise. Saves on fuel etc.
- village-idiot 8y agoYou have no idea how frustrated they make me.
- bmsleight_ 8y agoAbove a flow of around 3,600 pcu/hr (passenger car units) per lane, the roundabouts does not balance each direction effectively. (No gaps). Traffic lights (signals), can help improve flow further in these situations as well as giving pedestrians a safe way to cross. Part-time signals (only on a peak) can be very effective.
- village-idiot 8y agoThese areas are way below 3,600 pcu/h, maybe down in the several hundred to a thousand area. We’re talking residential side streets.
- eesmith 8y agoHere's a rotary in Boston (Sullivan Square) with a traffic light - https://www.google.com/maps/@42.3840002,-71.0744129,3a,75y,93.9h,92.48t/data=!3m6!1e1!3m4!1sbVGAmG4AjUqVjmr_SYBC_g!2e0!7i13312!8i6656?hl=en 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,40.71h,98.04t/data=!3m6!1e1!3m4!1srUWes0TAUF6xfW3zbactBw!2e0!7i13312!8i6656 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,84.8t/data=!3m6!1e1!3m4!1sro5iqQXJcisE7vdb3uxm4g!2e0!7i13312!8i6656 https://www.google.com/maps/@52.2084812,0.136931,3a,75y,82h,... .
- RightMillennial 8y agoAs an American, I detest roundabouts. I've never encountered one with a light before.
- oblio 8y agoWhy do you hate them?
- RightMillennial 8y agoNo 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.
- jermaustin1 8y agoYour 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 * Each entrance and exit has 2 lanes. * The outside lane of the circle directly connects the outside entrance with the "first" exit. * The middle lane of the circle and the inside lane of the entrance allows you to exit at ANY of the exits * The far inside lane of the circle exits nowhere without a lane change, but allows you to bypass an exit that might be backed up due to traffic.
- jpatokal 8y agoHuh? 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.
- jermaustin1 8y ago