Solving Traffic Conflict - Intersections and Interchanges Explained

[Music] everybody welcome back i'm yumble and today i'd like to discuss turning left in city skylines how do traffic engineers get cars to cross one another without having it back up how do we get cars to progress on the highway without the highway becoming a bumper-to-bumper mess this is a video about intersections in city skylines and also interchanges in city skylines and a natural progression from one to the other everyone thanks for being here let's talk about roads pictured here is a four-way intersection it's a lighted intersection so there is a traffic light managing the the flow of traffic and there's also an asymmetrical road which is giving us four lanes entering so you'll see each each side has two through lanes a left turn dedicated and a dedicated right turn as well so that is a fairly standard and slightly optimized four-way intersection facing an eternal amount of traffic all sides will always uh back up on a long enough timeline this is a highway's worth of traffic or even i would say eight highways worth of traffic flowing through it so it will never catch up a lot of you are probably thinking yumble the reason it won't catch up is because you're not using a roundabout i'd like to upgrade this to a roundabout and we will see what happens here we have an example of what i call a super turbo roundabout basically it's a kind of a turbo roundabout variant where we have a dedicated right turn lane on all sides so any car that approaches in the right lane can instantly enter without yielding and also exit free flowing so i think that's great and it looks like it's moving a bunch of traffic but unfortunately the tail back is actually it's actually way worse than the traffic light unfortunately nothing has changed as far as where the traffic is coming from or going i did change the road to be an asymmetrical three plus two which is fine that's actually what this roundabout wants but the the tailback goes on forever so those of you who said a roundabout is the answer unfortunately it does not cut the mustard and this is one of the more powerful ones that i'm aware of what is next there's got to be something better than this that can that can help us move these cars and here it is i've solved traffic forever no more traffic problems no more backups no more uh conflict points grade separation is the answer here you can see that i've used an overpass to separate traffic entirely the astute among you however may notice that no one is able to turn right or left the two roads no longer conflict but they also don't intersect anymore so no one has the option to go any any direction other than straight through which is good but that's only half of the solution now we have to figure out how to allow vehicles to turn right and left in between these two roads here we have a fine example of a cloverleaf interchange this is special because it's actually the first interchange ever invented it is free-flowing though imperfect the way that it works is all of your right turns are handled by slip lanes just like this blue truck exiting in the bottom right corner if that same approach wanted to make a left though they would cross the overpass once again grade separation is key with interchanges as we described a moment ago and they would take the first right afterwards netting them a left-hand turn the one drawback of this interchange is the weave as i said earlier it's free-flowing there's no conflict you never have to turn left against traffic so there's no need for a light or anything like that but you'll see that cars are constantly switching lanes in the middle here and they're switching lanes against one another so it's not simply a merge traffic coming up this leaf has to get out of this lane before the end in order to continue on and traffic that wants to use the lower left leaf to make their left turn has to conflict against that traffic so it is it is historic and it's free-flowing though it is very much imperfect there are other interchanges that can connect two major roadways or two highways or two interstates whatever you'd like to to connect without the weave this is the stack interchange it's actually a four level grade separated set of roads at the center point so none of the traffic has to turn left over oncoming traffic just like in the cloverleaf but there's also no weave so this is a perfect interchange essentially i would i would argue that it's the most perfect four direction interchange this is also in a class of interchanges known as system interchanges system interchanges are for connecting one highway to another but they are not the only type of interchange there's an entire other type of interchange called a service interchange which is for moving traffic on and off the highway so keep that in mind moving forward system interchanges are for connecting one highway to another service interchanges are for getting traffic off the highway and on the highway too i think that's where a lot of people get tripped up and they say why didn't you just build a stack i actually get that a lot i show all kinds of interchanges in previous videos how to build them where to use them and people always inevitably say it's not free flowing therefore it's a failure i argue against that i say that it's important to have smaller interchanges as well because not everything can be a stack and not every intersection can be free-flowing let me show you some example of service interchanges used for getting vehicles on and off the highway this is my personal favorite design for getting cars on and off the highway this is a partial clover leaf there are actually dozens of types of partial clover leafs but this one is a b4 partial clove relief the designation is denoting where the leaves are and which road they're coming off of but this is called a b4 you can see the highway is grade separated so it's underneath the arterial road and this six six-lane arterial can lead into your city so unlike the stack the stack really can only lead from highway to another highway it does not get you on or off the highway this one will effectively get you on and off the highway in mass quantities this is the same volume that the stack was passing the same volume that the the four-way light could not pass the same volume that the roundabout even an optimized roundabout could not pass this much traffic partial cloverleaf is of course much bigger than a roundabout but keep in mind it's actually much smaller than the stack so here's the for scale this is the stack that we were that we were looking at moments ago so if you're looking to get traffic off the highway don't use the stack it's massive it's expensive you cannot have every interchange be a stack unless you want to waste a lot of space and money and and it's just it's a lot so use something like this a partial cloverleaf other suitable options would include things like a diverging diamond or perhaps a single point urban interchange you can also integrate roundabouts into these if you put roundabouts where these intersections are you get some pretty great results i think that that actually reduces flow slightly on interchanges like this but it can be done of course right now i'm using lights on either side you can see how the lights are are cycling how traffic will stop and then be allowed in and and it's it's actually quite beautiful to watch over time but feel free to experiment with roundabouts if you would like everyone thank you so much for hanging out this one was was really fun to do i love talking about interchanges i love roads i like talking about the advantages and drawbacks of different types lights roundabouts interchanges the big takeaway here is service versus system so use a use a service interchange to get cars on the highway and off the highway use a system interchange to connect one highway to another know the difference feel free to ask questions in the comments feel free to join the discord i've been answering questions all the time there and we also have a very knowledgeable community surrounding this uh this city skylines project that we've all found ourselves in i also stream on twitch twice a week feel free to find me on twitch and come over for a stream if you'd like everyone thank you so much for hanging out i've been yumble i'll see you in the next stream or the next video [Music] [Music] you

Channel: YUMBLtv

Views: 146,625

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

Id: MXcfjxzqlkM

Length: 9min 7sec (547 seconds)

Published: Thu Nov 25 2021