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California debuts 'turbo roundabout' to fix intersection near Bay Area
- JoeAltmaier 3y agoSince there's no picture in the article(!): https://www.google.com/maps/place/CA-25,+California/@36.8954093,-121.4281083,361m/data=!3m1!1e3!4m6!3m5!1s0x809245cf89d3ac03:0xe3b64be1bb5e41ab!8m2!3d36.96275!4d-121.5462248!16zL20vMDY2MG1x?hl=en&entry=ttu https://www.google.com/maps/place/CA-25,+California/@36.8954... Oh! The road diagram includes the new roundabout but the satellite picture hasn't been updated!
- altairprime 3y ago36.89558° N, 121.42738° W
- notatoad 3y agothis article seems to have some actual pictures: https://metro.co.uk/2024/01/04/californians-will-get-used-using-a-turbo-roundabout-20061551/amp/ https://metro.co.uk/2024/01/04/californians-will-get-used-us... the previous configuration as shown on the satellite image looks a lot like the intersection Tom Scott made a video about, where the intersecting road is angled to keep cross-traffic hidden behind a car's a-pillar. https://www.youtube.com/watch?v=SYeeTvitvFU https://www.youtube.com/watch?v=SYeeTvitvFU
- JoeAltmaier 3y agoWell, artist's renditions anyway.
- alkonaut 3y agoImagine designing an intersection between two roads with two lanes in either direction as a flat intersection. It's being lazy and cheap to the point of being criminal. Or it's almost like it wasn't really designed at all, it just sort of happened because two roads crossed. The way those roads are long and straight leading into the intersection too. Crazy. Any drunk/unattentive driver is going to go what 40-50mph against a red light right through that intersection. Good thing they removed it. Few hundred of those left to fix I'm sure. The road overlay shows the size of the roundabout really isn't much larger than the original intersection either.
- pitdicker 3y agoAnimation of a turbo roundabout: https://www.youtube.com/watch?v=AkmelZhvlPk https://www.youtube.com/watch?v=AkmelZhvlPk (or search for 'turbo rotonde', there is a lot of material in Dutch available). There are over 2000 of these turbo roundabouts in the Netherlands.
- Freak_NL 3y agoOr rather, 'turborotonde' if you want Dutch sources where it was spelled correctly.
- bombcar 3y agoIt seems it's a spiral that doesn't let you loop forever.
- x3n0ph3n3 3y agoYou could, you just have to keep changing lanes to do so.
- yurishimo 3y agoYea, the point is to choose your direction in advance to minimize cross over traffic and lane changes. It will likely take a few weeks for people to get used to getting into the correct lane for their journey, but maps applications are already well equipped to handle these due to their increased use in Europe.
- jurmous 3y agoThey have been here in the Netherlands for decades so feels odd to see it is such a novelty in California. Happy to see they work there too!
- gpuhacker 3y agoIn the city where I live, also in the Netherlands, we had multiple of these but all of them got converted back to normal intersections with traffic lights and it has been a huge improvement.
- yurishimo 3y agoCan I ask where? I just moved to your country in late 2022 so I’m not sure what I would search for to read more.
- badpun 3y agoMy understaning is that normal intersection with traffic lights has higher troughput (as cars can just fly through it at or near 50 km/h if the green light is long enough), but roundabout have lower average wait times (if the traffic is low to moderate, you usually wait less that 5-10 seconds to enter the intersection).
- pi-e-sigma 3y agoNo, simple roundabouts are worse in both throughput and wait times than normal intersections with traffic lights. They are however safer, and that safety is precisely thanks to slowing traffic town, which means that collisions are less frequent because drivers have more time to react and if a collision happens it happens at lower speed. Just think about it: how can wait time be smaller and throughput higher when cars approaching a roundabout from _any_ direction need to slow down compared to normal intersection where cars on one road can wizz through with full speed?
- badpun 3y agoTo answer your question: wait times can be lower because, if the traffic is low enough, ALL cars just wizz through, at the cost of slowing down while entering the roundabout. Whereas, for the intersection with traffic lights, a significant number of cars will hit red light and have to wait for a minute or two.
- colmvp 3y agoI'm not sure why roundabouts are so uncommon in North America. Where I live, at a 4 way small street intersection, two of the entrances have stop signs with a roundabout in the middle. At that point, you might as well get rid of the roundabout.
- coolhand2120 3y agoI think I live in a typical US CA city and there are dozens if not hundreds of roundabouts in this suburb. And I don't understand why you would have stop signs AND a roundabout. I am hoping someone can explain this feature to me. It just seems like extra chance for confusion and extra source of danger because of that.
- jedberg 3y ago> And I don't understand why you would have stop signs AND a roundabout You shouldn't. It's a poor design choice to cater to Americans who aren't used to roundabouts and yield signs. It makes things less safe.
- rootusrootus 3y agoIt's also a reaction to poorly placed roundabouts that are severely unbalanced and heavily used. Not every intersection is well suited to become a roundabout.
- badpun 3y agoWait, Americans aren't used to yield signs? Is this in general, or only in the context or roundabouts?
- jedberg 3y agoI've been driving in America for over 30 years and while I've seen them occasionally, they are very rare. And when I do see them, almost no one understands how they are supposed to work (go slowly until you know there is no one already there). They basically either don't slow down at all or stop like a stop sign. It's not really covered when we learn how to drive. We get maybe a page on it in the handbook and one question on the driver's test. And then the road test almost never has one since they are so rare.
- altairprime 3y agoLooking at the old intersection on the satellite map photos, it’s a classic obstructed-A-pillar deathtrap with traffic lights glued on as a failed band-aid fix. See also Ipley Cross, which had the same issue until it was altered last year or so into two right-angle T-intersections separated by a few hundred feet: https://news.ycombinator.com/item?id=23024275 https://news.ycombinator.com/item?id=23024275 (4 years ago, 144 comments) The DOT pages for the Gilroy project may be of interest: https://dot.ca.gov/caltrans-near-me/district-5/district-5-current-projects/05-34490 https://dot.ca.gov/caltrans-near-me/district-5/district-5-cu... http://sanbenitocog.org/wp-content/uploads/2023/10/Turbo-Roundabout-Project-Fact-Sheet-101423.pdf http://sanbenitocog.org/wp-content/uploads/2023/10/Turbo-Rou... [pdf] http://sanbenitocog.org/wp-content/uploads/2023/10/SR-156-Improvement-Project-Fact-Sheet-091823.pdf http://sanbenitocog.org/wp-content/uploads/2023/10/SR-156-Im... [pdf] For those in other regions: US traffic signals generally permit a right turn at a stop/red signal after coming to a complete stop, do not use photo enforcement to detect red light violations, and are sometimes ignored by drivers when they don’t see any cross-traffic worth slowing down for. These three properties exacerbate the safety issues with scissor intersections and inhibit the effectiveness of signaling-only fixes.
- gene91 3y ago1 and 2 can be addressed though. It’s easy to ban right-turn-on-red on a specific intersection. People sometimes do not see the sign, but new-style electronic no-right-turn signs addresses this. https://www.orangetraffic.com/wp-content/uploads/2017/08/LS2828-R3-1_Web-Size-1.jpg https://www.orangetraffic.com/wp-content/uploads/2017/08/LS2... It’s also legal to have red light cameras, so they can be installed.
- altairprime 3y agoAmerican drivers disregard those electronic signals almost as readily as they disregard unlit signs, stop signs and red lights; especially in rural farmland regions such as Gilroy. (Less so when it’s due to a train track, more so when it’s due to impaired visibility.) Red light cameras are a somewhat effective solution for attentive drivers, so long as their car has a license plate (which is also not reliably enforced in the US). However, the inherent flaws of the scissor intersection, and the risks posed by inattentive drivers, are only addressed by replacing the scissor intersection with something else.
- modeless 3y agoWe drove through this last week. It's not done yet but it looks very confusing. If they were everywhere people would get used to it but with just one I think it may cause problems. And they can't be too common because they are absolutely huge compared to a regular intersection.
- yurishimo 3y agoThey are bigger but when people learn how to use them (only takes two or three encounters) then they massively increase throughput. Here in the Netherlands, a roundabout is always the first choice and only if space is a limiting factor is a light used. But nowadays, the lights are really smart and can sometimes change to green for a single approaching car if there is space.
- andrepd 3y agoAlso, roundabouts (as well as many city streets) have only 1 lane, and relatively narrow at that.
- pi-e-sigma 3y agoWhich is ironic because roundabouts were initially sold as solutions making road intersections more safe, not as means of increasing throughput. The reduction of crashed and injuries comes from decreased speed of cars. So obviously it's at a cost of throughput
- andrewflnr 3y agoIt's only obvious if you're confusing throughput with latency. Also, you're comparing with stoplights, a system where you often stop dead rather than slow down. So it's obvious to me that increasing safety and througput at the same time is very plausible.
- pi-e-sigma 3y agoThat's indeed so obvious that in Europe there is a new trend of reverting roundabouts back to standard intersections. Because in reality roundabouts slow everything down to unbearable speed. EDIT: you make a mistake assuming that just because traffic going through a roundabout doesn't completely stop that it automatically means that the throughput is higher than a stop-and-go traffic through normal intersection. And also assume that traffic going through a roundabout never stops, which is simply not lined up with the observable reality
- notatoad 3y ago>This breaking news story has been updated. lol yes, the months-long process of constructing a roundbaout definitely qualifies as "breaking news"
- gosub100 3y agocompletely random thought: a roundabout is technically vulnerable to a DoS attack if enough drivers coordinate their efforts and just drive around in circles. Unless there is a law compelling drivers to choose an exit, that's technically different than a DoS attack by stopping in the roadway.
- avidiax 3y agoRoads and intersections have a similar DOS attack. Just "break down" in/on them.
- cornholio 3y agoYou can DoS a road by placing a log or a long vehicle across it, no need to get fancy.
- pi-e-sigma 3y agoIt's not the same, because driving in a circle on a roundabout is not obviously against the law
- nkrisc 3y agoIt is the same because if you’re blocking traffic they’ll stop you, law or no law. And almost certainly there is some general law against impeding traffic anyway.
- pi-e-sigma 3y agoYou are not blocking traffic though because you are driving. That's the point. If driving can be considered blocking traffic then the police can also stop you for driving on a straight road because you also taking 'capacity' out
- nkrisc 3y ago> You are not blocking traffic though because you are driving. That's the point. Then if you’re not blocking traffic, there’s no DOS, and there’s no problem. > If driving can be considered blocking traffic then the police can also stop you for driving on a straight road because you also taking 'capacity' out They can and they will. If you’re impeding traffic in any way and it’s causing a problem, they will stop you. This isn’t code. There aren’t loopholes. There have the power to stop you and they will if you’re causing trouble. Even if it’s “technically legal” they’ll still probably arrest you just to stop you and let you go later.
- aosmith 3y agoIs this a "turbo roundabout"? https://maps.app.goo.gl/uxt1E7snorKLPxjC9 https://maps.app.goo.gl/uxt1E7snorKLPxjC9 If so there are a lot more than 2 in the US.
- coolhand2120 3y agoWhile I don't see any pictures of the turbo roundabout in the article, it does say there are raised lane dividers that prevent traffic from changing lanes, so this does not look like a turbo. There are a few multi lane and single lane roundabouts in my city (US,CA), none have raised dividers. Sounds interesting. Roundabouts in the right place can really help with traffic. In some places they're just dumb: 4 way STOP sign WITH a roundabout for example, yes they do exist, wish I understood why.
- Scubabear68 3y agoWe have one of the dumb ones in NJ, circle at 202, 206, 28, with 202 going over it via a bridge. It is a very high stress round about where you can be stuck for some time waiting for an opening during rush hour, then you have to make a mad dash to another stop sign.
- jay_kyburz 3y agoI was surprised to discover there were round about you are allowed to change lanes in. Here in Australia, all roundabouts are like this. If you enter in the outer lane you must take the first or second exit. If you enter in the inner lane, you must only exit on the second or third exit.
- rootusrootus 3y agoDoesn't look like it. A turbo roundabout is a spiral, not just multilane.
- bloopernova 3y agoOh boy, I can't imagine how much the local facebook groups would complain if a new different turbo roundabout were to be installed where I live. Despite there now being at least a couple dozen roundabouts within 15 miles of here, every new installation generates a cacophony of kvetching. There have been roundabouts here for almost 2 decades now but people still treat them like the devil himself created them. Thankfully the number of people going the wrong way around the one near my home has diminished to almost none. Back on topic, I like the design of this, it sort of sidesteps the lane changing that larger roundabouts use.
- jahewson 3y agoI live in the Bay Area but I grew up in the UK where we have lots of great roundabouts and I can tell you that the roundabouts in California are beyond terrible - why? Because pedestrians have right-of-way at the roundabout entry/exit points, so cars have to constantly stop on the roundabout, defeating its very purpose. Indeed, there's usually a marked crosswalk at every entry/exit (and even if not pedestrians have the right of way on "unmarked crosswalks" in CA). In the UK roundabouts are the only place where pedestrians don't have right of way and there's always a small island in the center of each (unmarked) crosswalk, so only one direction of traffic needs to be crossed at a time. The cars flow around the roundabout and don't stop.
- chrismcb 3y agoAre you sure about that? I'm not a UKian but the rules seem to imply that you have to give easy to pedestrians at roundabouts
- fatnoah 3y agoYou should come to Massachusetts. We up the ante by adding stoplights, stop signs, left turns, and pretty much any permutation of road topology.
- crote 3y agoYou can avoid that issue by offsetting the pedestrian crossing one car's length from the roundabout. This allows a single car to stop and yield, while allowing subsequent cars going to other directions to continue unimpeded. It also reduces the angle between driver and pedestrian, greatly improving visibility. You can see this in practice at [0]. [0]: https://www.google.com/maps/@52.1124016,5.1914329,70m/data=!3m1!1e3?entry=ttu https://www.google.com/maps/@52.1124016,5.1914329,70m/data=!...
- kccqzy 3y agoThe DOT's video on using this roundabout is actually very clear and well made: https://m.youtube.com/watch?v=KHYo7Bl_zWg https://m.youtube.com/watch?v=KHYo7Bl_zWg I'd say it does a better job than the linked article to explain how this roundabout is different from a usual roundabout and how the lanes work.
- rootusrootus 3y agoThe article doesn't have any pictures of the roundabout, best I can tell. This article does, though: https://www.ladbible.com/news/us-news/us-turbo-roundabout-california-gilroy-306320-20240104 https://www.ladbible.com/news/us-news/us-turbo-roundabout-ca...
- jrpt 3y agoI’m not anti-roundabout but for $15 million could they have made it a highway interchange instead, raising one road, lowering the other to go under? Looking online it seems like it’d cost about the same amount for an interchange.
- altairprime 3y agoThey do intend to build a highway interchange, but noted that since it will be at least 2028 before it’s finished, that they wanted to put in an immediate safety mitigation to reduce crashes for the next 5-10 years while that’s planned and built.