Roundabouts may NOT be as Good as you Think - Full Experiment and Explanation
HTML-код
- Опубликовано: 22 июл 2024
- The magic of the roundabout. A feat of traffic engineering, but the design has its limits. See this experiment from start to finish with full explanation on how to perform the experiment yourself!
Interchange Test Map: steamcommunity.com/workshop/f...
Traffic Manager Mod: steamcommunity.com/sharedfile...
Roundabout Roads: steamcommunity.com/sharedfile...
7 Lane Asymmetrical Road:
steamcommunity.com/sharedfile...
➤Mods Collection: steamcommunity.com/workshop/f...
➤Patreon: / yumbltv
➤Discord Server: / discord
➤Watch Yumbl Live: / yumbltv
➤Instagram: / yumbltv
➤Twitter: / yumbltv
➤Steam Workshop Collections: tinyurl.com/y4u7lcnn
#citiesskylines #roundabout #yumbltv
0:00 The Hypothesis
0:48 The Map
2:30 Traffic Manager Settings
3:57 Traffic Light Setup
5:51 Traffic Light Observations
6:51 Roundabout Setup
9:37 Roundabout Observations
11:25 Three Lane Roundabout Observations
14:17 Reinstating the Traffic Light
16:54 Thank You!
17:37 "The Real Kicker" 
Игры
Thank you all for the interest in this video! The hypothesis presented is supported by real world data as well.
Those who would like to prove the traffic engineering community wrong now have the control environment to show it! I appreciate your comments, but I really look forward to all of your thoughtful presentations :)
I'm curious about your traffic light setups. You set them up to be "only one cardinal at a time" but I wonder what would happen if you split up the 'straight through' traffic and the 'make a turn' traffic. so leftright for a while, updown for a while and then right/left/right/left and left/right/left/right (if you know what I mean).
I see that type of light configuration a lot in my local city, where it allows for seemingly more throughput as a lot more traffic tends to want to just go straight and there's less traffic volume making turns. So it's set up so that the straight through phases are prioritized and last longer.
It would be interesting seeing a video about different traffic light phase setups, depending on the traffic volumes. (Hell, I suppose there's even an algorithm you could run over it if you knew the makeup of the traffic)
The light can be much more optimal. For sure
@@YUMBL I agree with your conclusions. That said - something to think about. In the UK, a high traffic, high road count, high lane count roundabout like that would not be implemented like that. First there will be traffic lights. Secondly, lanes will always tend towards the outside - so you get into the correct lane for your exit and it works it's way outward so you are in one of the two outside lanes when you need to exit. That's how they get their large throughput.
Thank you! I just thought CS players deserve to know as well.
@@YUMBL Yes then it works even better when you set them up manually. ruclips.net/video/6mHPgjhPCE0/видео.html
Hello. Traffic engineer here. The magical (potentially frustrating) thing about intersections is that there is a lot of hidden complexity. While it may seem a simple case of two roads worth of traffic intersecting, this is incorrect. The efficiency of traffic flow through the intersection depends on many hidden variables that require a lot of thought both in real life and in game.
In this case, the traffic lights are vastly optimal compared to a roundabout for probably multiple reasons, the most pressing as far as I can tell being the ultimate destination of cars passing through that intersection. For some reason, perhaps an unexpected result of the setup, it is evident from the traffic light time lapses in this video that the vast majority of cars are passing straight through the intersection as opposed to left or right. This kind of intersection greatly favours the traffic light. From a mathematical point of view, traffic lights benefit from very high flow from individual streams one at a time whereas roundabouts service multiple streams simultaneously at a lesser flow. Keeping this in mind, it makes sense that a traffic light would work better here since almost all the traffic has to cross the path of another stream. Roundabouts are much more suited to balanced directional traffic where the ratio between left, right and straight turning is closer (In actuality a perfect roundabout would have every car go to the right as then there would be zero conflict but that would defeat the entire point of having an intersection).
This isn't a perfect analysis, indeed such a thing is impossible without extensive computer simulation, but I just wanted to highlight that I certainly think there are situations where a roundabout may come closer to or even trump a traffic light in a high density traffic scenario. Although you are correct in that people are very "passionate" about roundabouts when they are certainly not the solution to every traffic scenario as some people seem to think.
Very balanced response! Thank you. I have yet to see a spot where a big roundabout beats a light in a high density situation though. They just seem to break down earlier consistently. I havent found a source that confirms that either. The light seems to maintain flow due to its versatility when traffic starts stacking in a way that roundabouts cannot.
Within the roundabouts threshold it thrives. Space allowing you to build it in the first place. Above that and its backup city. Then countries seem to add lights to the roundabout.
i definitely see your point...but unless a city is designed with no road hierarchy, most of the traffic IS and SHOULD be traveling straight.
@@YUMBL We do have Roundabouts in Australia where the side roads to the roundabout have traffic lights to allow the main roads to have a better chance of clearing the peak hour traffic. Then the main road stop and allow the side roads to clear. The main through road to the roundabout might have 2 or 3 lanes, while the side or local road has 1 lane. These lights are only activated during peak hour traffic times. It more like a hold back to avoid a frustrated motorist on the side road waiting 10 minutes to try to cross the main road peak hour traffic from trying to barrel through causing a accident (crash). Though as the traffic increases, they change these to full signalised intersections.
instead of ‘dealing’ with traffic, maybe reducing car trips would have a bigger impact on throughput than either a light or a roundabout-
we should de-incentivise car travel instead of paving over cites with asphalt to cater to them-
a generation of ‘urbanism’ that panders to motorists has gutted American cities, leaving us with free parking and stroads. It’s terrifying that terms like ‘walkability’ need to exist, what a deep hole we’ve dug for ourselves.
I've done a research paper for university on roundabouts as a civil engineering student and my conclusion was that roundabouts are more effective in areas that have stop signs (or lower traffic volumes) rather than traffic signals (much higher traffic volumes). Arterial roads wouldn't benefit much from roundabouts as the volume of traffic is immense. Collectors and local roads have a much better benefit with roundabouts as the traffic isn't as demanding. While this video is a great example of how effective traffic lights can be, it wasn't optimized to the fullest extent as it appeared the left turning traffic was far fewer than through traffic. Maybe setting up a protected left only for a minimum of 5 seconds and then through traffic only for your times would improve the efficiency of that intersection even more.
All entirely true. I wanted the light to be easy to set up as most of the community swears by roundabouts. A good light will decimate the best roundabout.
Now a lighted roundabout…
@@YUMBL my research paper didn't include lighted roundabouts lol!
Yea. Once you add a light most of the charm and appeal of the modern roundabout disappears. The reasons people like it and such. Still probably safer than a regular intersection, but large. Efficient, but at what cost?
@@jacobgathman289 We do have Roundabouts in Australia where the side roads to the roundabout have traffic lights to allow the main roads to have a better chance of clearing the peak hour traffic. Then the main road stop and allow the side roads to clear. The main through road to the roundabout might have 2 or 3 lanes, while the side or local road has 1 lane. These lights are only activated during peak hour traffic times. It more like a hold back to avoid a frustrated motorist on the side road waiting 10 minutes to try to cross the main road peak hour traffic from trying to barrel through causing a accident (crash). Though as the traffic increases, they change these to full signalised intersections.
Can you provide said study? Urbanist im formation here 🙋♂️
Now this I HAVE to watch!!! Edit: Interesting video. Question: did you turn on the TM:PE Traffic AI at all as watching the roundabout with all the "not really giving way" that kept happening I'm not so sure it was on then?
🤣🤣🤣
#SaveTheRoundAbout
I'm with you, @biffa... I know your way of setting up roundabouts, and I agree with it, but @yumbl makes a good point as wel, had the same experience... both have a use and place :)
@Biffa Plays Indie Games They all had yields, yes. By shift+ctl clicking with the yield its sets the whole thing up. I did it in the video.
@@YUMBL No I saw that, I mean in the TM:PE settings menu you can turn on the Advanced Vehicle AI. With this the game can cope better with a lot of things, particularly these alien builds we love so much, called roundabouts and the yield signs added with TM:PE. Without it the game seems to work better with traffic lights, which are a part of the game like stop signs. But with yield signs the game tends to need the Advanced Vehicle AI to help them get how they should work. I normally go for around the 70% mark :-)
I feel the biggest problem run into with traffic lights, is players let the game keep the cycles far to short to REALLY give them a chance to work as desired. The areas approaching these intersections need to be well planned, otherwise you're going to have to cause some disruptions to established areas to fix them later.
And then those roundabouts end up like this: ruclips.net/video/N0HoqjxfvJ4/видео.html
IRl long cycles are quite frustraing, especially if you are waiting for a turn with short window. And, frankly speaking, if you need to squeeze percents by fine-tuning traffic lights, you likely have bigger problems.
25 seconds is short compared to many actual lights
@@permeakra But, we aren't talking IRL. People don't give themselves the space for expandability within many areas, especially at the beginning. So, they're afraid of expanding a road to lose businesses etc... and losing population, afraid that it won't rebound. This video is a great example of road planning, lane mathematics and management. I have to agree with him, in that Roundabouts are overrated. They're fine for collectors and secondary. But arterial and highway either need far too big of a round about with limited input lanes.. or high volume lights. There will never be a perfect solution to any of them. Frankly, anything above 60% is pretty good.
@@717dash_cam 1-lane roundabounds are fine, 2-lane sometimes work - but you need to make them really big. Never disagreed with that. Point is, at some point traffic problems are not solvable by optimizing locally. The game represents that part of RL quite fairly =).
I find that roundabouts work best for medium traffic density, and they can sometimes be useful for low traffic situations with three roads coming from odd angles. But, the absolute best way to avoid traffic back-ups is to diffuse traffic with multiple route options, and just use simple intersections. Also, pay attention to road hierarchy. Using roundabouts as a default intersection is, in my view, a bad idea. It takes up space, and simply organizing your road system will solve most problems.
This is true!
👍🏻 _Multiple direct routes diffuse traffic_
@@LeeHawkinsPhoto MMLT!
The best BEST way to diffuse traffic is to ban cars 😏 can't be traffic if there is no traffic.
I found this very interesting. It really comes down to how much time one wants to spend evaluating the traffic entering the intersection. In a live game, if there were let's say a large industrial complex feeding the south arterial one would have to evaluate and modify the timing on the lights accordingly (so that not all of them are 15 and 25) and occasionally revisit the location to monitor that the traffic flow hasn't changed and thrown the previous settings into chaos. This is both entertaining and educational.
Integration with real time would be interesting...
Finally someone who doesn’t put a roundabout everywhere where they have a traffic problem. As someone who also enjoys optimizing traffic signals in CS, one of my favorite scenarios is timing traffic signals on one-way couplets to create the “green wave” for the platoons, works great, and I haven’t seen anyone demonstrate it yet.
Thank you! One day i’ll master the green wave. Just tinkering til then ;)
Here in the UK we know about roundabouts, your 3 lane roundabout before converting to lights was all set up wrong, traffic was changing lanes when they shouldn't making joining traffic give way. You need to use NODE lines to make them stay in the correct lane depending on where they are going.
e.g. cars on the south side heading west should be on the INNER lane until they get to the north part, where they would switch to the middle lane. I saw cars on the left lane (which should be going west) actually turn off and head north. Cars in the middle lane can either go EAST or North, if they go north they SHOULD stay in the middle lane and exit on the left or middle lane on the north exit, but they cross over to the outside lane at the east junction forcing the cars coming in on the east (and heading north) to give way.
Hope this makes sense, hard to explain really. google something like -- "UK 3 lane roundabout rules" but reverse it for your side of the road since we drive on the left.
Roundabouts have their place but are most certainly not the miracle they are portrayed to be at times. I use them but only at very specific intersection scenarios.
Bingo!
Maybe simulation and reality is not identical?
*in city skylines*
in which situations would placing a roundabout be beneficial?
Lower flow collector roads, space allowing. Roundabouts are excellent.
I'm a roundabout addict in Cities Skylines, I've actually never used a traffic light before. You convinced me to give it a try, thanks for the tip on the timing settings!
Finally somebody said it. Never understood the love of them in skylines, given so many of their real world advantages don't really matter that much (safety, and no need for power or maintenance of lights. Efficiency in low-medium traffic is still good though). We don't use uncontrolled roundabouts in high traffic areas even in the UK. Most of our large busy exchanges are roundabouts with lights controlling them, not least for the reasons you noticed. If you have lots of traffic flow in either NS or EW routes they will tend to 'lock', giving you very unbalanced flow. Turning left is extremely slow if there are no gaps in the traffic. Left turning traffic conflicts with everything, even left turning traffic from ahead (traffic lights can let opposite left turns through). In high traffic situations you need some system for letting people turn left, otherwise left turning traffic tails back and starts to mess up other junctions.
Where roundabouts really shine is wherever you might use a multi way stop, as it achieves the same thing but avoids people stopping when there is nobody obstructing them. If you have one route that is used far more often than any other through the junction then you don't need to worry about balancing controls. That's great right up till it gets saturated. Roundabouts are a great default junction, because they have fantastic behaviour the majority of the time with very little effort. That doesn't mean they are the best performing junctions.
Its much better than a four way stop, no doubt. Collectors can work too, but not on big roads.
If you make them properly, they're better than any intersection
Absolutely untrue 🤣
@@xenn4985 I mean tbf, America could really do with building their cities not centered around cars so much.
@@xenn4985 the times I've visited, everything about your cities is mostly about cars and driving, the amount of space you dedicate to psrking lots is astounding to me. The city i come from in the uk is around 250k people and is only 40km big, its just one of the things i noticed, hell even london isn't built around cars it has insane level of transport links. (then again uk has tiny houses compared to us and all are built of brick generally we don't do wooden prefabs or anything often) its not a dig.
Very interesting. I've tried using both in C:S. Initially, in my city, I had the entrance to the city a huge roundabout with traditional TM:PE settings for a roundabout. It had nonstop backups. I tried the same roundabout but with traffic lights at each end, timed them together and it worked okay, though at times the backups were worse than without lights. I then set up a four-way timed traffic light and it worked amazing. I do use timed traffic lights a lot in my city, probably more than I should.
I also don't get the point of having 100% perfect traffic flow. I find backups in traffic cool to watch. They represent reality, and sometimes it challenges you to making amends while also keeping it real. Backups happen.
Thanks for the video!
Thanks for watching :)
One time I was playing C:S and I was like "You know, wow, I could really quite easily recreate my entire city here in the game."
And I did...and the traffic started backing up to the point it broke medical services, couldn't transport the dead, couldn't leave the city, couldn't enter the city.
The way to fix it was by adding an additional lane in and out of the city on one of the highway connections. Instantly cleared it up all the traffic!
I guess that's the problem when you focus all your industry in one part of the city and rely on highway connections to drive workers in with no available public transportation and a horrendous grid system.
People who seek perfect traffic flow are the kind of players who meticulously curate their cities like a bonzai tree. For me at least, I like to make the fictional world as great as possible for the fictional citizens. One element of that is good transit. 90% is the baseline but so far it dies at 60-70k for me.
The stoplight could actually be timed even better. You could set the light to trigger a shorter window for both ways to turn left, then both directions to go straight at the same time so you can clear N-S and E-W as the same time. Also if you add slip lanes to the traffic light, it would probably be the best of both worlds, and the most efficient.
Simultaneous protected lefts would be great. In fairness, the roundabout could be better optimized too. The public's recommendation to have two exit lanes here hurt efficiency because for whatever reason, you can see the cims are, even when turning right, entering the center lane and inhibiting the through-traffic. I agree though that for this configuration of heavy through-traffic the traffic volumes are reaching the limits of what a roundabout can do, and not offering any of its advantages.
Finally someone has the courage to say what I've been thinking for ages now.
We love our roundabouts in CS. I just thought someone should acknowledge the limitations :)
I think roundabouts work best for traffic that unevenly comes from one direction and splits into a few side streets (example: one of your main entrances to an industrial area splits into a few side streets and if you use a light it tends to cause backups coming in, but if you use yield signs it also causes backups on the side streets) or on streets that get sporadic traffic (example: a few streets down from lighted intersections). In most cases more roads going to more spread out places in your city seem to clear traffic faster. Instead of only one way to get in and out of your busy area, do at least three going to completely different areas of the city.
And at about 14:40 there's that dentist office waiting room feeling again.
But on a serious note: I really really wish some of these traffic management mods would be made for Transport Fever 2. Because the traffic lights in that game only function to build heavy backups. And no matter what you do, no matter how many lanes a road has, only one is ever used.
Brilliant content. Especially how you established the test conditions. That was great as it allows for making actual comparisons.
Thank you! I hope to see others attempting this :)
The king of intersections at it again haha. I will say from my own observations when driving here in the UK, the larger roundabouts tend to be traffic light controlled anyway. So perhaps the reasoning is more to do with the relative safety of roundabouts compared to 4 way stops rather than pure flow
I've actually used a few configurations for arterials that simply could not handle roundabouts - as you so aptly demonstrated, roundabouts can fail HARD in high traffic situations.
1) Mini-interchange, using overpasses and ramps. Think of a system interchange shrunk down tiny. The tinychanges can have their own problems, though, especially if there are any conflicts.
2) Timed traffic lights and slip lanes. These can be VERY effective, even more so than your test light.
3) Overpass bypasses. I measure the traffic flowing from different directions; if everyone, say, is trying to turn left and jamming the intersection, I'll put an elevated left turn in and signalize the ground level intersection. This is a specialty trick, and requires the Vanilla Overpass Project assets, but it can be AMAZINGLY effective if you have unequal traffic at a major intersection.
Love the experiment, but I think a lot of this is dependent on the type of traffic and the sizes of the roads. As you say this works for high throughput areas. If you are going for massive 7 or 8 lane roads that is highway grade arterial roads. Roundabouts will probably be fine for roads with a third of the traffic and no more than 4 to 5 lanes.
I have seen those 12 lane roads on the workshop and figure that you could replace all of the highways on a map with those, and drop having any interchanges.
BTW, any way to change the default numbers on the Timed Traffic lights. When setting them up it takes ages to fill in the numbers. Even with the copy function it is a pain.
Thank you! Idk if you can change the default numbers
Great video. This is something I suspected for a long time, too. Using timed lights vs roundabouts, in any configuration, really, shows that timed lights are always or almost always superior for high density traffic. I hope to see more in-depth and more scientific videos about intersections :) Maybe some mod to actually measure traffic flow?
I ran into this problem a while back, so I made a really compact full clover for collectors (the biggest roads I tend to use outside of highways). If you set up traffic manager correctly it flows almost completely freely for most traffic conditions and takes up about the same space as the roundabouts I tend to make. I'd be curious to see what a magic roundabout would look like here, but that would be even bigger.
I recreated this with the following changes:
- Enable Advanced Vehicle AI: ON
- Dynamic Lane Selection: 100%
- Simulation Accuracy: Very High
- All cases simulation run for 10 minutes:
Case 1: Default timed traffic light
- Traffic Flow: 54-59%
Case 2: 3-25 second timed traffic light
- Traffic Flow: 49-54%
Case 3: 3 lane roundabout:
- Traffic Flow: 43-47%
Case 4: 4 lane roundabout:
- Traffic Flow: 54-58%
Case 5: 3 lane highway roundabout:
- Traffic Flow: 66-69%
Conclusion: In City: Skylines, 4 lane roundabouts and default timed traffic lights produce similar traffic flows. While using a highway produces the best results, it's the least realistic. (centripetal force would be pretty intense)
Note: The issue with roundabout traffic not giving way is solved by turning the simulation accuracy up.
Cool experiment! The percentage is less helpful than seeing the cars imo, but counting vehicles would he ideal. I wish we had a counter
@@YUMBL Toll Booth = counter
Actually? How? I’ve never used them 🤣
@@YUMBL One of their stats when you select them is "cars charged last week" or similar. It's not perfect, but it's good enough to see if there's enough difference to actually bother. Make sure to put them on the outgoing traffic only, so it's not affected by any tailback from the intersection under test. For the typical 3-lane highway, the large one-way booth (8-kiosk) can usually handle the full load. Using traffic manager to force the traffic to split up at the booth is helpful sometimes, as is turning on automated tool-booths (higher speed through the booth).
Wish traffic manager was part of the base game
This is some excellent data. I'll have to try out this map myself to see if I can make roundabouts work.
Two things I'd like to see; using node editor to embiggen entrances, smoothing out the curves to increase vehicle speed / reduce sharp turns, and setting up traffic lights on each roundabout entrance. Yeah, really. That's a pretty common setup in the UK as it prevents the roundabout backing up, though I wouldn't know how to set that up in TM:PE. Roundabouts with traffic lights are the go-to service interchange here.
Cromulent suggestions, sir.
Do it!!!
@@YUMBL okay fine jeez
also I love your single point partial cloverleaf, it works so well
Damn we have a ton those traffic light roundabouts here in India and they work unexpectedly well in CS
Buy some squares and connect it all the way back at the interchange. Then use lane connectors near the intersection so theyve already picked their lanes.
So satisfying watching the timed traffic lights and seeing all the lanes being used. I've always preferred them to roundabouts in the game since they take up no extra space.
Popped in from Biffa, thanks this is quite informative.
I've used a couple roundabouts to replace lights, but in almost every case I've had to remove them and upgrade to something better. If a 4/2 asymmetrical intersection with timed lights won't keep up, chances are the roundabout won't either. I've upgraded a lot of my major intersections to simplified CFIs, and although they take quite a bit of setup with lane arrows etc, they do move a lot more cars. Partly that's due to just having more lanes available, and partly due to being a 2-phase traffic light.
This was extremely interesting! I never understood the fixation with them and have never seen them effectively used in heavy density. Even in real world they are a pain to navigate as you run into the proverbial "who's on first?" routine.
Yup found this in a game called Motorways. Roundabouts are mostly good for big intersections but for small ones a traffic light is just what you need
Hi, do you happened to find any mods that allows us to manage hotkeys? because I can't seem to find one.
I started to play again since yesterday, and I want to manage my mods hotkeys, in order to know if there's anything that conflicted to each other.
edit : another thing I wanted to ask is, does the newest version of NC Renewal (currently it's on 3.1.3) finally support the ability to edit individual segments? I'm still on the old 2.2 since it doesn't fail on me yet and also because the last time I know (around May to August, I think), NC Renewal still hasn't included that feature.
You've convinced me that roundabouts don't work as well as traffic lights for high density (in cities skylines), all though I'm still going to try to make it work with this interchange testing map.
Roundabouts are still my choice for lower density intersections, especially when I have more then 4 streets intersecting at once.
Lower density roads DESERVE a roundabout, space allowing. Thanks for watching :)
Awesome video! This generated a ton of discussing and reading the comments was enjoyable. It was odd to me that most traffic wanted to go straight; I don’t understand the game’s rng and why it would prefer intercity routes to be fully across the map
tbh I think this is not so different from real life. Roads are built along important routes, meaning traffic will want to go straight (stay "en route") most of the time when hitting an intersection or interchange. As infrastructure continues to develop and more destinations spring up, the existing road may be sufficient to act as a route between these new places, so you get additional right or left turning traffic from this. But if that left or right turning traffic becomes too much to handle, you can create a bypass road along this route, splitting these two important routes onto separate roads so they don't intersect anymore. But that just means traffic will want to go straight again.
This is all because of a basic property of geometry. Let's consider the location of an interchange and call it A. Then let's pick two destinations so that to get between them via A you need to turn left or right. These are B and C. Going from B to C via A can _never_ be the shortest possible route from B to C. It _may_ be the shortest route _currently available_, but it may also not be. On the other hand, if you're going straight across an intersection, this theoretical "idealness" of your route is not impacted. Other intersections, or even bends in the road, will likely do so, but the issue there is not with the fact that you've used the intersection.
TL;DR: turning has more potential to make a route longer than it needs to be than going straight, so it's likely that hypothetical turning traffic will be able to find a better route, removing them from the intersection entirely.
I just discovered this channel, high quality stuff. Keep going.
Thanks a lot :)
This video blew up pretty quickly for a Skylines game. Nice work. 🤘
i've subscribed to that map, and i'm gonna use it to test some stuff. for example, i'll try a different setup for the traffic lights. instead of letting cars from one direction go while cars from the other 3 directions have to wait, i'll try this:
1st phase: cars from the north AND the south are allowed to go straight
2nd phase: same for east-west instead of north-south
3rd phase: cars from the north and south are allowed to turn left
4th phase: same as 3 except east-west instead of north-south.
and of course everyone is always allowed to turn right.
pretty sure that this setup will increase traffic flow but i'm willing to be proven wrong.
Do it! Test all the things, share all the results!!!
@@YUMBL i have a lot of things i want to test.
@@mrxmry3264 maybe setup screen recording and share the results? Obviously doesn't have to be a full video, just some clips.
yeah i was wondering too why cars were not allowed to turn right on the lights full time^^
Also if you have right turn only lanes then the adjacent direction can turn right while the other traffic is still going. I tend to do 4 cycles like that and leave 1 for pedestrians only. Traffic is not a thing any more.
Tl:dr: timed traffic lights and micromanaging which lanes go where can have some extremely beneficial results.
For my building style (which is more on the American cost-saving side) I only use roundabouts where there is only a moderate amount of traffic (which they are best for IMO) I have plenty of space I know I won’t need, there is little or easily redirectable pedestrian traffic, and if there is industrial traffic that will make me have to change the dimensions of the roundabout.
I always think to my self if a roundabout is really necessary when a traffic light or some signage will get the job done just fine so I only use roundabouts when I believe they are perfect for the situation
I’m not against roundabouts I just don’t think they are the best traffic solutions to ever exist (at least within cities skylines)
PS: great video it really shows how roundabouts in the game don’t work great with really heavy traffic
Interesting argument. With traffic flow, I tend to do a DDI or stacked roundabout. Though when I do make roundabouts, I normally don't do a 90-degree input. Usually brace the roundabout with the inputs at the 90-degrees, but then add lanes to those inputs at about 45-degrees from them. It's a little bigger, due to needing 9 extra roads to reach their destination, but it seems to work. Though I do have spots on a map where that didn't work.
In my current city I have replaced most of my roundabouts along the arterials with timed trafiic lights since the roundabouts always seemed to cause more backups. So I agree with your point. However, where I still have roundabouts I make sure that the roads connecting to the ring come in at an angle (not 90 degrees). That seems to greatly improve the flow and it would be interesting to see a new comparison where both the traffic lights and the roundabout are fully optimized.
After 3,756.5 hours of playing this game I’m glad someone is finally saying it. I ONLY use roundabout intersections at 1/2 asymmetrical roads or 1/1 roads in suburban neighborhoods. I believe in grids. Grids work. High density cities work avoiding using too many highways is the best bet for the vanilla gameplay start small build out organically and focus on walkability and bikes I avoid placing Stroads all together if possible. I was wondering if everyone is so afraid of Biffa 😂 that they have to play just like him.
I have similar experiences. I've followed suggestions such as lowering the roundabout speed "to let more cars in" but all that seems to do is reduce throughput. I've also made it bigger, added slip lane right turns, etc. but stuff like that just makes it take up more room and eventually approaching the size and complexity of a proper interchange. Meanwhile the timed intersections move a lot of traffic in a small amount of space.
Honorable mention goes to raised or lowered roundabout functioning as an arterial exit, but that's still medium duty in my opinion. I think roundabouts can offer utility in suburban settings, like a low density neighborhood transitioning to a strip mall area. Otherwise I think the big benefit of roundabouts is that they're probably the best option when Traffic Manager isn't available. The vanilla lights are absolute trash and, in my opinion, worse than completely uncontrolled intersections. Due to lack of lane control, many common heavy intersection configurations aren't viable in vanilla C:S.
Personally, I set the traffic light minimum time very low, usually one second but up to four, and use the flow control slider to control traffic. This way I don't need to be concerned about dead periods where nothing is moving when traffic is asymmetrical, which is probably usually the case. The ideal configuration is the one with the fewest light cycles since you lose throughput during light changes. As this video suggests, very long cycles typically moves the most traffic but the roads need to be configured in a way where the cars can queue. That is, it's not going to work well when there are intersections right next to major junctions like this. In those scenarios, the flow meter needs to be set more to the right for more frequent light changes.
There are more options to handle pedestrian traffic with a timed intersection. Even under "auto" settings they tend to get in the way of cars less than when crossing the roundabout. They can be given their own light cycle, which is fun to watch. It's like having your own Shibuya crossings. Pedestrian overpasses or tunnels are options in either case, though.
A very reasonable conclusion :)
@YUMBLtv how did you come up with 15 to 25 as traffic light settings? Are there even better adjustments?
There are. This was not an optimal light in the slightest. Still better than a roundabout in high density traffic.
one thing that always gets me about multi-lane roundabouts is that if you have to turn left on them, you have to cross 2(+) lanes to get in to your lane, which can be close to impossible sometimes. so that can easily cause massive backups, with the traffic lights you just wait for your turn and empty the entire lane all at once. so as nice as turbo roundabouts are, i'd never really go for one with more than 2 lanes, if you need more, use multi-lane traffic lights like yumbl did, or just make it a highway interchange
The outer lane should always be the merging lane and the default lane
@10:07 something isn't right there. The cars on the roundabout stop to give way to quite a few cars entering the round about and they shouldn't do. This has a knock on effect blocking other exits. Maybe it is the AI level?
Show me the solution!
@@YUMBL 2:40 turn up simulation accuracy in the TMPE settings :) Otherwise they just won't yield properly.
@@thebestspork This plus as seen in some of the footage with the timed traffic lights, some of the vehicles jump the lights and attempt to cross traffic before it clears. Simulation accuracy needs to be high or very high if we want to be as realistic as possible when comparing junctions.
SHOW me.
@@YUMBL So it appears it isn't the AI setting that does this, the Simulation accuracy seems to control how well the ai responds to the yields. With it set to very high, they will stop on yields as needed 95% of the time. That doesn't solve the traffic flow though, the timed light is still better even with the yields working
This is what I’ve always thought. Every single bad intersection I’ve ever had was very easily solvable by using timed traffic lights: no need for the removal of buildings and it always seems to work much better than roundabouts!
The most traffic-heavy areas of my city all have custom set ups of traffic lights that conform to the needs of the specific intersections (like longer green lights on the main road, for example). And my traffic flow rarely ever dips below 85%. The city is at ~340k pop.!
Woo Hoo like number 1.8K! An interesting experiment. Now to see what Biffa has to say about it. Keep up the great work!
You are absolutely correct, Yumbl. I had to switch out a lot of roundabouts for a 4-way lighted intersections because I've found roundabouts to be inefficient.
Just on the biggest roads, but yes.
@@YUMBL Correct. Only on the biggest roads. No matter what I tried I could not get my roundabouts to flow in heavy-traffic conditions. I finally gave up, removed them, then added a 4-way timed-light...and voila!
I'd like to see the comparison between a grade separated interchange and the lighted intersection to compare their throughput this way.
Excellent idea! I bet it gives lesser interchanges a run for their money
This please. Especially if there is some sort of automated way to generate intersection statistics, like average speed, or cars per second, average waiting time, or something. It also would be interesting to see a (super)turbo roundabout tested.
I would love some sort of flow meter. Believe me, i’ve asked around.
yumbl: conclusively roundabouts are not the best option for high density roads in cities skylines
commenters: I CAN'T BELIEVE YOU HAVE DISPARAGED ROUNDABOUTS, THEY WORK WELL IN LOWER DENSITY CONFIGURATIONS, THIS TEST DOESN'T ADDRESS MY PARTICULAR USE CASE
would be dope if people actually watched the whole video before feeling the need to defend their beloved roundabouts
This is so fun 😂
Dutch Civil Engineer here. We do love our roundabouts.. but only where it is applicable. High density crossings with a lot of traffic from multiple directions will be signalized. They have a much higher throughput than roundabouts (if you time the lights correctly), at the cost of safety and often higher lifetime costs. Roundabouts have fewer (50%) accidents, and far fewer (75%) fatalities/serious injuries compared to regular crossings due to less difference in speed between vehicles/bikes/pedestrians and angles of entering the crossing.
For every traffic amount and type, every amount of space and every situation really there's some particular setup that's working best. That's what makes traffic so intriguing in real life and CS! I definitely have to learn better how to set up timed lights now though.
Traffic management to me, is the most fun AND most frustrating aspect of the game 😆
It absolutely makes the game :)
I tend to agree that in this particular instance that a roundabout doesn’t hold up well. However I don’t think a roundabout would be built in this scenario with heavy traffic going in all directions. The roundabout works well when you have a singular dominant flow of traffic that you want to prioritise without holding it up with (even short) light phases
Must admit, I had no idea how to set up,a timed traffic light on an individual basis so just the shortcut has helped massively!
Oh, its so good. You may need to play with timing, but its a life saver.
As a Texan who travels this big state it is hard to find round abouts so I am a little bias about signaled intersections. However, Texas has had it's many shares of unique hybrids that are part roundabout, part signaled, and part overpass. It's really interesting how TXDOT really builds their roads. Love the videos thank you for them and keep making them!
Yeah! Down with roundabouts! Stack interchanges everywhere!
Here, have a “mini-stack”!
I'm a dedicated Biffa fan, so I LOVE roundabouts. But this was a fascinating video, and a very compelling demonstration. I think you might get even better results by altering the timing of the lights and playing with some of the advanced options ("more waiting than driving", etc.).
The light was suboptimal, yes :)
On mainland Europe, the most common kind of roundabout is a single lane roundabout, possibly with sliplanes, and often three-way rather than four-way in the industrial / commercial / office areas that are often found between large roads and cities. There they work nicely. For anything heavier, you will find interchanges, where there is space, or intersections.
Agree 100%. I hardly ever use roundabouts anymore. I only use them as an aesthetic choice when I know the traffic isn't going to be too bad. I use tm:pe simulation accuracy at very high and the dynamic AI lane selection at 70 and the timed lights are far more efficient. Medium traffic on one pair starts to choke the traffic on other street pairs and heavy traffic just kills the whole thing, but a well set up traffic light keeps everything under control. Just have to tweak the light to find the right timings sometimes.
That's pretty close to scientific proof, very well done.
You could slightly boost it by telling straight lanes to ignore the very right one, leaving it for right turn only. Then modify lights to right turn always green or "allow right turn in Red" in TMPE Options. Single-Node- Sliplane
However, I still love watching traffic at roundabouts, not stopping at lights. For eyecandy I'd still opt for the roundabouts.
High appreciation for your kind way of presenting, thanks
Thank you! I think both look great :)
FINALLY!! Someone who doesnt throw friggin doughnuts at every traffic issue whether it makes sense or not (and in many it doesnt).
One main excuse is safety...but this is a game...plus, you cant have fast moving, high volume traffic 3-4 lanes wide "controlling itself" to yield, merge, shift lanes in circle, get out, etc properly or efficiently or there would be a pile up every 5 minutes. Seriously, people are stupid and dont pay attention; they crash regularly on the straight highway trying to change lanes and more often at on\off ramps, bringing traffic to a hault for miles...yet you think they could handle a roundabout like this? Lol, thats hilarious.
Yeah they work in cases, but so does many other things. To me its a theme thing, not a best function thing...but everybody for some reason doing CS videos started using them everywhere, maybe the lazy way out? I cringe even hearing the word as ive seen many ppl on here build them religiously, got to the point i stopped watching builds and especially traffic fixes because i already knew what was coming. Thank you for giving me hope again!! Lol...
Anyway love ur vids dude, you do nice work
Thank you :)
Very interesting concept! You've presented something to ponder and try out in my city.
Using the same 4 by 3 asymmetrical roads you show here, I'm truly curious about how asymmetrical intersections would be built and react; to clarify, you have a 4-way intersection but only eastbound and northbound traffic entering the intersection are heavier. Even more specifically, northbound to westbound (heavy left turns) and eastbound to southbound (heavy right turns). Would it be as simple as increasing the available turn lanes (left, left/straight, straight, right and left, straight, straight/right, right respectively) in those heavier flows? Hmmm...
Could the traffic lines been made to have the left turning traffic avoid the right lane and then the opposite road could turn right there even when it is red for 2 if the three cycles? Does this make sense?
_Biffa will remember that_
Yeah I've reached the same conclusion. I still think they have good uses though but they're by far not a catch all solution.
Edit: also thanks for the test map, I was curious how you did your testing, I'll definitely be getting this.
Hmm where Biffa at
At the top comment :p
when I set up timed traffic light I mostly set it up like a Dutch traffic light, with it having more phase configurations and having a 0 second minimum so that traffic manager can pick which phase would be best and it works wonders
Came here to the comment section to see the "Biffa goes REEEEEEE" in his British way, and I was not disappointed. Looking forward to his response XD
*Europe has left the chat*
Sorry, disagree with this video entirely, you can't make a custom intersection (Which worked very well), and compare it to a basic roundabout. The thing about roundabouts is, the busier they are, the larger they have to be. If the roundabout was bigger, had proper exits and entrances and slip roads, roundabout always wins. I had a nightmare city once, with 3 main intersections on the main road. I changed 2 of those to roundabouts (pretty big, proper slip lanes) and my traffic was cured almost instantly. Always love your vids, but I just don't happen to agree with this one.
Was this a basic roundabout? 4 lanes, fully managed? Can I count on you to create an experiment to show me, or is this a flippant comment?
@@YUMBL to be honest, I don’t see what is flippant about it. I happen to disagree also, since roundabouts are pretty much a solution on multiple occasions. It does need sliplanes, vehicle AI upped and good speeds on entering and on the roundabout itself. Setting a nicely managed timed light with separate lanes versus a regular roundabout is not an equal footing.
Also actual turbo roundabouts are a different beast entirely.
Its only a flippant comment if one is unwilling to back it up
@@YUMBL not to be pedantic but he wasn’t being disrespectful.
One thing I did notice on the intersection is that people are actually waiting a long time. Although the roundabout has one lane on two sides stretching out, it would be interesting to see what the actual throughput is on both. I’d reckon it is not all that different, given the fact that the actual backup doesn’t seem to keep expanding.
No one was being disrespectful. I dont really know what you mean.
I've noticed this, too. A good lighted intersection is great
Does this only apply to asymmetrical roads?
I wouldn't expect additional turn lanes feeding into a roundabout to do much anyhow. Though these lanes go all the way to the highway... I understand asymmetrical roads are common in the US, but with 16 lanes leading towards the intersection/roundabout and only 12 leading away from it, aren't the additional 4 mostly wasted?
Notification Squad, let's GO!
As an englishman I quintessentially disagree
If custom demands, I understands.
The inner most lane would only really be useful for a U-turn. The best way to think about it is to number the lanes from outside to in - the number would correspond to which junction you want to exit (so the outer most lane exist at the 1st opportunity, next one at the 2nd opportunity, etc...)
In Argentina we don't turn left on avenues or highways. It's not a thing! You have to turn 3 rights and it's totally fine. Well, we do have designated left turns but they are very circumstantial.
So you're saying a roundabout doesn't work for a junction it wasn't designed for, big shocker.
By making this one junction the only connection between highways it's essentially a system interchange.
A roundabout is not a complete system interchange, it cannot cope with all that traffic. It can however be part of an interchange if you grade seperate the through movements and use a roundabout for left & right turns only.
This video is an unfair experiment because you are trying to make a roundabout do something it simply cannot do.
The function of a roundabout isn't for dealing with a large volume of traffic. The function of a roundabout is to increase safety over a normal junction with traffic lights.
The traffic light didnt seem to mind ;)
Might not be a big shocker for you or I, but seems to be news to quite a lot of people. The setup is quite artificial, as all experiments are, but it is entirely possible to set up worse conditions by accident, and this is a good demonstration of the limits of roundabouts. The whole point of the video is that it highlights what roundabouts cannot do.
The challenge is not insulting Biffa at the same time, which is I think why it's tone is so scientific.
I do find it is more complicated than "this works better than that for getting traffic through." There have been times I've turned roundabouts into lights and saved traffic, other times I've turned lights into roundabouts and things started flowing more smoothly. I also was one time having problems with a backup on a diverging diamond, changed it to a single point and saved traffic (even though many argue DD is better than SPUI). Traffic is complicated, and you have to approach each intersection the way that situation calls for.
Thank you for doing this.
I agree i've seen an over-reliance on roundabouts with a lot of mayors on youtube, and I think traffic lights are most likely the better option, though I would have loved to see this using a 6 lane double-turbo roundabout. On a 3-way roundabout, I have used a 4 lane road, with 2 lanes for each direction, and it worked significantly better than having 1 lane for each direction. I think you'd probably have to use a 6x2 road coming into the roundabout - not sure if any exist on the workshop, but i don't think the 4-unit width is wide enough for a 6x3, though i might be wrong.
After trying out RABs throughout my city, and YES I configured them properly with the right tool, I figured out regular intersections configured properly were much much better than RABs!
Wow!
That actually changed my mind about roundabout.
I used to think that roundabout saves everything.
Now, I will plan better!! THX YUMBL
Thanks for watching :)
As with every type of road junction they are useful in the right situations. Once you reach a certain density of traffic they do create traffic backups, so a lot of very busy roundabouts here in the UK have had traffic lights installed on them to help keep the traffic flow even.
One of the main advantages of them IRL is the safety aspect, which is obviously not something that needs to be considered for the simulated traffic in C:S.
All correct :)
I'd love to see follow-up build (or series of builds) on the idea of an arterial interchange or grade-separated roundabout - especially w.r.t size. IMO a huge convenience of timed traffic lights is that they scale so well: assuming the roads stay the same width, you don't need to build anything new as load on an intersection increases. If there's a way for roundabouts to exploit verticality to compete with timed traffic lights that would be very cool.
Excellent idea!
@YUMBLtv you talked about potentially doing a grade separated interchange between the arterial is that something you could do a video on? It seems like I always end up with the one junction that timed traffic lights would work on, but I always wish for something that could be more free flowing.
Like with vanilla overpass?
@@YUMBL kinda except connecting 4/6 lane two way roads kinda like this video.
At 13:42, we see on the round about, (right side, middle lanes of the round), that they stop to allow cars enter the round about.. in TPME Biffa usually stop incoming cars (not just the yield sign, the move when intersection opened. and on the round about they should just keep going), Not sure if that would be enough however, but it seems like an important feature of how roundabouts work.
Great video, would be interesting to check vanilla traffic lights vs vanilla roundabout
Very interesting experiment. I tried to reproduce it, but I found that roundabouts were slightly better than timed traffic lights. However, I was using the 3-lane highway as a roundabout circle, and I was using the vanilla 6-lane road for the intersection (as well as arterial roads). In my games, I almost always used the highway as a roundabout, simply because I want a 3-lane one-way road, and the game only has that as a highway (without downloading assets).
I presume the 7 lane roads and different roundabout might explain the difference.
It’s an interesting experiment, well set up. I don’t agree that it proves that roundabouts are worse than traffic lights though, because every type of intersection has a design capacity and all that is demonstrated here is that the traffic flow in this scenario is greater than the design capacity of this particular roundabout. In my experience roundabouts work great when you have up to two lanes in each direction and an asymmetric flow (arterial meets a collector, or collector meets local road, or arterials or collectors meets in a T-junction, or two local roads meet). In any situation where you have a constant flow of traffic from any direction, you don’t want a roundabout (alternatively you’d want to add signals to the roundabout).
The cims were driving quite fast as they headed into the roundabout or, at least, they tried to maintain the same speed they were driving on the straightaways heading into the roundabout. Did you change the speed limit of the roundabout? Outside my neighborhood just north of Los Angeles, three arterials and a freeway overpass converge on a roundabout. The speed limit on the arterials are all 50 mph, but the speed limit in the roundabout is only 15 mph.
Gotta appreciate the effort to actually test this ! But I would like to add that idk for the us, but in France 50 m diameter for a roundabout is quite small. It’s what most light traffic roundabouts would be like. Huge roundabout r usually more than 100 m in diameter (sometimes up to 300 m). And for traffic lights 15 - 25 cities Skylines time units is quite long (and would be in comparison a long time for a traffic light in France).
Still appreciate that you actually took the effort to test this.
It was a 56 meter RADIUS. Not diameter
@@YUMBL Oops my bad. Misheard it
I'd like to see your version of a flyover interchange that tries to keep the same ground footprint as the intersection. Bonus points if you can keep zoning at or near the intersection.
Would you have a single level flyover, or stacked? Would you still keep a stoplight at ground level? I'm thinking a tunnel and bridge for the straight-throughs, plus a ground-level intersection just for turning.
Love the chill music.
I've been using Roundabout service interchanges for my cities, but this and one of your other videos might have me reconsider and put in a partial cloverleaf! I've already converted a couple to SPUI to some pretty nice results, especially one that emptied in my city's downtown area!
Spui is a great option :)
Try the new Hybrid SPUI Parclo Yumblty made, its fantastic, best of both worlds
Hi
I watched some of your roundabout videos they are really interesting
I live some where that is really crowded place and roundabouts are every where
So much traffic no road management
there is no collector roads
and residential and commercial is a nightmare how they managed to spared it
Just watching your videos gives me so much ideas you know
Simulation is a really great way to apply things before making a thing
Thank you very much :)
Thanks for the video.
Did you time how long traffic took to pass through the intersection/roundabout? Visual inspection is not as accurate. I am not sure roundabouts must clear like an intersection as they are designed to flow, even if it is a bit stop-start. .
I will have to try this but it seemed visually that the longest wait on the timed intersection as set up was about 18 seconds and the roundabout was similar or quicker.
Let me know what you find!
What about double roundabout ? Is it possible to make them in this game ?
That part at the end where you added one more straight-through lane was what my brain was yelling the entire time, and of course the results were to be expected! One thing I was also wondering about this type of intersection, what would the results be if you had opposite sides have equal left turn time, then equal straight through time, and then guaranteed right lane turn time while the adjacent lines performed the same setup? While it may be very American to have a single side (North, South, East, West) go individually, even more common is opposite sides doing the same thing in conjunction with each other.
The light was intentionally sub optimal. So i could use the same road for both and to make it easy to replicate
Idk if this is better, but Biffa always has an extra lane in the round about. so if it is a 4 lane road (2 lanes in each direction) or a 5 lane road (2 into the round about, 3 out of the round about) for example, the round about would have 3 lanes. 1 lane more than what is feeding into it.
I just banned cars in the city, and residents get somewhere exclusively by public transport. There are almost no traffic jams, only on the end sometimes, but if you build the final ones correctly, there will be no traffic jams. Public transport top!