Roundabouts are NOT as Good as you Think - Full Experiment and Explanation

everybody welcome back my name is yumble and today we're going to do an experiment my hypothesis is as follows roundabouts are not the best option on high density roads in cities skylines i'll say it again roundabouts are not the best option on high density roads in city skylines controversial i know today i'm going to set up a whole experiment and we are going to compare a lighted junction so a traffic light to a roundabout i'm going to show you how i set the whole thing up i'm going to show you videos of all the results and i'll also challenge you to perhaps perform the same experiment if you're curious about my results and would like to check for yourself everyone thank you so much for being here i'm yumble let's do an experiment today our experiment will take place on interchange testing map this is a map from the steam workshop that serves to generate traffic to test out flow on interchanges and intersections essentially traffic will automatically flow around this ring road because that will be the fastest route unless you delete some of the connections i want to show you which connections i choose to delete today just so you can replicate this if you decide to uh if you decide to do your own experiment so i'm only using the cardinal roads north south east west but there's eight connections around the outside so what i'm actually going to do is delete some very specific segments of road to group roads together to force traffic to run a certain way so by deleting this one in the kind of bottom right section and this one in the bottom left section i've grouped these two spawns together which will force traffic to if it wants to pass to any other spawn it'll have to go through the center area so i'm just going to do the same thing to these two forcing these two the the north northwestern and western spawn points to go through this western area we're going to group northeast to north and that should automatically group east and southeast to be from this connection traffic may choose to use this to turn around and go back out that's that's fine i'm not really gonna worry about it too much but this is going to force four separate connections worth through the middle i'm going to convert these into arterial roads for the test we're doing today and i'll be back in just a moment traffic manager president edition is also going to be very important to this experiment so just in the interest of transparency my normal settings are simulation accuracy low under general under game play i like to turn on disable despawning so this will stop cars from disappearing if traffic backs up that's going to be important and i like to turn on enable advanced vehicle ai i usually like 20 there the rest of it isn't really going to matter too too much for this particular particular experiment and here are the arterials i haven't actually this was a default traffic light that appeared automatically but i've connected more transparency i've connected the highways in in such a way you can use traffic manager click it with the lane connectors button and hit control s to just make this connection happen for the fourth lane you can use this if you want you know connect that there make sure they can use all four lanes if you're using an asymmetrical road like this this is from the ultimate us roads pack but you can use any asymmetrical road to to pull this same thing off and also i like to do junction restrictions i'm still not sure what this button is called but it allows traffic to enter blocked intersections so just so the road is seamless and free-flowing i'm going to do that to all the different corners and then we'll see how this sets up now that all four entrances are set up identically i'd like to do a control traffic light so we're gonna go to traffic manager click timed traffic light and i'm gonna control click the intersection just for a very much a default traffic light you'll notice i've got the four lane road facing the intersection and the three lane road facing away from it that's just a standard i would call it a standard north american traffic light as i know it where you have a dedicated right turn lane a dedicated left turn lane and two through lanes usually into two or three roads on the other side so this will do fine for the test but the traffic light is going to be slightly modified from default timing-wise i'm going to hit stop and i'm gonna edit these instead of being a minimum time of three seconds and a maximum time of eight seconds i'm going to do something a little different maybe like 15 to 25 i think so i'm gonna i'm gonna raise that up and i i shouldn't really have to change it throughout the experiment i don't think so 15 to 25 on each of these and what that really means is each cycle will have a minimum time of 15 seconds in its current configuration and it will detect cars passing through the intersection and if there's no flow after 15 seconds but before 25 seconds has elapsed it will move to the next cycle i'm not even going to touch any of these these are all default the the more advanced settings i don't tend to worry about them and i think i said 15 to 25 cool and start so this is our control traffic light you can see it operating here i'm gonna let the game run for a few minutes and just wait until traffic arrives at the light and we'll we'll see how it goes oh there they are i have been observing our control traffic light for the last maybe 15 to 20 minutes give or take and this is definitely a high density traffic simulation currently all of the highways are converging right in the center as they should and things have kind of reached equilibrium at this point and you'll see it's actually keeping up with it quite nicely the the timings seem okay i just i generally have a vague idea of what the timings may need to be and within one to two cycles everyone is making it through no problem so the tailback is just non-existent right every time a group of traffic arrives at a light virtually the entire thing is able to clear or for example let's see what this one does yeah i think everyone that was waiting initially was able to clear so that is a very successful light i would like to take this same configuration same traffic same everything and convert this into a kind of a modified roundabout and see if i can make it work the same i received a lot of feedback about the roundabout that i used in my previous video about different types of junctions for turning left in city skylines so i'm taking that into account today i'm going to be using a larger roundabout so i'm going to use a 7 unit roundabout which is pretty enormous that is a 56 meter radius which is which is quite quite the hefty roundabout and i'm going to be using a four-lane road as well for consistency so a four-lane one-way road excellent another sort of concern that was that was uh that was uh presented to me was using node controller on these i'm not going to use node controller people had concerns about that the node was too big for traffic to grab spots in the yield i'm also going to clear the traffic just so the roundabout has the same opportunity as the light did so you'll also see here throughput was a concern a lot of individuals were concerned that there were two lanes queuing up to go into the roundabout to go straight across or rather that there were two lanes queuing up at the light but not at the roundabout so i'll show you how i'm going to overcome that these are typical roundabout settings i've what i've done is i've clicked the priority signs button hold shift hold control click it automatically sets up the roundabout a certain way kind of in a turbo roundabout style but what i'm actually going to do ignore the way the marking looks it's going to look a bit funny but i'm going to allow two lanes to exit so pay attention to lane 3 up here i'm going to allow a right turn from the second lane ignore the left arrow there is no left but that's just the way the the visuals look for the turbo roundabout road or maybe other roads too i've never actually set up a roundabout this way but people really want me to have two lanes able to queue so the way that this works out in its current state i think this is everything that i need to do to optimize it i think that's actually it obviously there's yields on all sides things like that but each of these lanes corresponds with one of the lanes in the roundabout as they do in city skylines the rightmost lane is just a right turn exit where you're forced to exit the second lane could also exit the roundabout or they can cross into one of these lanes here and then exit so now you have a a second straight across option for the roundabout i'm going to let this run for a minute in its current state and we will see how it handles the same amount of traffic that the traffic light was moving here is the state of things as you can see most traffic will favor the two middle lanes of this four lane entry situation because those two lanes provide them the ability to go all the way across and come out the other side so on all sides the center lanes are favored the right lane tends to clear very quickly whenever cars arrive there and the left lane appears to barely be used at all the left lane i think you would you might need it if you were trying to um make a left turn though perhaps with the fact that we're using this second lane in as a straight through and a right turn that may change the turboness of the whole thing entirely in reality it could probably be a three-lane roundabout now that i think of it but the result would be the same so what we're looking at here is everything is working as intended sometimes the cars yield sometimes they don't but the yields are set up i promise you that if you look at three of the four sides there are tailbacks going for quite a distance the right side tends to clear every now and then though right now it's actually getting a little backed up the right side the the eastern side i haven't rotated the game at all in fact i've marked i've kind of established a true north for for us for consistencies um the right side tends to clear every now and then which allows a little a little relief on the roundabout for everyone else but all the other sides it is it's absolutely a nightmare going back probably a thousand meters or so sometimes more uh this side is starting to catch up but i i don't think it will this side is trying to catch up i have not seen any side but the right side actually catch up in this configuration um maybe let's reduce this to a three-lane roundabout and we'll we'll see if that fixes anything here is our three-lane roundabout variant and i've given this about 10 or 15 minutes to run and really it looks very very similar to the four-lane i don't think that this provides any more or less throughput honestly a side effect of it is that the leftmost lane isn't used on any sides but that's okay i'm not i'm not interested in modifying that road to to suit this really looking at the tailback on all sides the top side tries to clear and sometimes the bottom side gets close but for the the left and right or east and west sides they always have an extended tail it seems on this one i i do not think this is faring nearly as well as the traffic light did i think that by doing such a large roundabout we've any any smallness or any space saving measures that small roundabouts may have this does not have that at all i was looking at things that can fit in the middle and this is the small park the vanilla small park can fit in the center of this the small park is not actually small it's actually pretty big when compared to like other parks so in a downtown setting i don't think this is actually viable unless you make a lot of space by putting the buildings out a little bit and of course walkability and bikeability would suffer with this type of thing as well seeing as as how pedestrians would have to go out of their way to to go around the radius of the thing i think any flow benefit is not even worth discussing i don't actually see any any tangible flow benefit on this one i see a lot of it backing up around the sides i foresee some people trying to say that slip lanes may be a good option not that the not that the lighted intersection required slip lanes to function but that the roundabout might benefit and i don't see that that's the case the right lane seems to get out right away like as the right lane shows up it almost gets to enter on all sides uh immediately so you'll see this lane should all clear in just a moment once this bus moves i don't think it's an issue of slip lanes that's that's holding it up because largely it's traffic that's trying to go straight across this also has um the center lane exiting as well so two lanes can enter to cross and exit as well but yeah i i don't see it as viable on higher density roads this side's getting out of control now and it seems that the longer i leave it this lane appears to do okay over time but for some reason east and west tends to to back up pretty hard and that was once again not occurring with the traffic light here's the real kicker are you ready i'm going to take this and convert it back into a traffic light and see what happens give me just a moment what i've done here is reconnected the intersection as it was at the beginning of the video and added the same traffic light you'll see 15 to 25 standard traffic lights it's already been started i've not unpaused the game i figured that we could kind of watch this together and see what happens [Music] we appear to have entered a state where traffic has cleared on all sides and it's been brought back down to a one to two cycle weight i want to say leaning towards one cycle i think the the last car to arrive in a platoon is generally getting through the intersection at this point um not only do i think that a traffic light is a better option on high density roads in city skylines i think it's it's a good space-saving measure in city skylines i think it runs more traffic there's a bit of a learning curve to setting it up but as you've seen i've i've done it twice it's really not that bad so i would strongly recommend trying out traffic lights in your city if you're looking to to shake things up a little bit i do sense that there's a bit of an over reliance on roundabouts probably due to their ease of setup and also their kind of legacy irl right it's a very uh beloved intersection in real life due to its uh reasons of safety right reasons of uh ease of maintenance it doesn't require maintenance like a traffic light things like that but i want to say that uh conclusively roundabouts are not the best option on high density roads in city skylines i think there are better options if you're willing to if you're willing to check them out such as a traffic light or maybe sometimes your arterial should even have an interchange so maybe that roundabout ought to be grade separated something like that but everyone thank you for watching this video i i hope that you enjoyed this i hope you think that the experiment was well founded and well carried out and if you don't i'm really looking forward to to seeing what you come up with feel free to join the discord if you'd like to share the results of your own experiments let me know how you think i misrepresented the roundabout this time please respectfully of course and of course feel free to check out a twitch stream if you'd like i stream twice a week and uh i'd like for you to subscribe on youtube as well if you're if you're feeling it i try to do road experiments all the time and see what works see what doesn't everyone thank you so much for hanging out i've been yumble i'll see you in the next stream or the next video now here's the real kicker add one more straight through lane and it is not even close it is not even remotely close

Channel: YUMBLtv

Views: 66,887

Keywords: roundabout, mods, city skylines, detail, vanilla, smooth, smooth roads, node controller, intersection marking tool, move it, anarchy, fine road, pinwheel, interchange

Id: yK4T09tyaAw

Length: 17min 53sec (1073 seconds)

Published: Tue Nov 30 2021