Solving Traffic Conflict - Intersections and Interchanges Explained 

The best part of designing intersections in CitySkylines is how obedient and patient the drivers are. No moving violations. No crashes. No road rage. And I also imagine the drivers being polite enough to thank me for my great design as they pass through. Happy Thanksgiving, YUMBLE!

I've been playing Cities since 2016 and I never get tired of roads and traffic management in this game. It feels like an endlessly changing and chaotic challenge that you never quite manage to get perfectly right.

i have a city that's been having major issues with traffic despite following all of Biffa's advice and converting as much road to bike-friendly roads and encouraging biking, making things walkable, overhauling transit, etc. my biggest pinch points were always interchanges. i used your tutorial to create a parclo from scratch in a really strange section of the map that a symmetrical, 90 degree interchange wouldn't fit, but i was able to manage it and it cleared up traffic significantly. thanks for making such good tutorial videos and explaining your reasoning every step of the way, it's proven really helpful!

Alternate British Title: The Art of turning Right.

My favourite service Interchanges are single roundabouts, where you dump traffic onto an elevated or lowered roundabout to redirect them in other directions, or a turbine / single elevated road turbine managed with TM:PE since you can get some crazy compact, arguably minimal free-flow intersections

I'm an architecture student, and you'd be surprised about how much we learn on the effects of traffic flow and how the design of roads can make a place feel 'beautiful'. nice video man, im with you on the partial clover leaf, i use that in my cities all the time. Also whats your graphic settings??

From a driver's perspective, I have always loved going through a cloverleaf, especially because of the weave lane. I find that the nature of the weave forces incoming and outgoing cars to actively cooperate with each other to exchange places with each other, which makes for a very smooth transition. Contrast this with ordinary merges, and drivers already on the freeway rarely if ever accommodate new traffic from the merge lane. They can have an attitude of "it's your problem and if you run out of merge lane I don't care" with no negative consequence to themselves, whereas on a weave lane, even a selfish driver must help to create an opening if he wants to receive one. I also find that a cloverleaf's forgiveness of mistakes can be a huge stress relief on the driver. Once you get into the loops, you can completely miss your merge and all you have to do is pass around the other loops to try again. This is silly but it's a lot less silly than going five miles down the road to the next interchange because you made a whoopsie and missed an exit you didn't mean to. This can cut down on dangerous last-second lane changes as people are less desperate to avoid missing their exit when the consequence is not so harsh. It also never forces you to exit from the passing lane, which is harder to do than exiting from the non-passing lane. Getting into the passing lane can be difficult especially when contending with impatient residents of the fast lane who do not care about the fact that they are now sharing space with people who want to exit - they just want to cruise and not be impeded in any way. I don't know how any of this is represented statistically since I'm just a layman, but I suspect that the drawbacks of the cloverleaf may not bear out in practice as badly as they seem like they ought to on paper.

Good stuff. I think what was left unaddressed was how to classify and solve the problem you initially presented, a high traffic urban intersection of two non-highway arterials? Perhaps a bypass roundabout? The tail on the turbo roundabout's traffic seemed to be primarily from cars wanting to go straight through. I always end up making a spaghetti stack in those situations, and hiding it underground in shame.

My personal favorite: the cloverstack hybrid. It eliminates a clover's weaving, but cheaper than a full stack. Also, try using cloverleafs with collector lanes to eliminate weaving. Dual trumpet interchanges are also useful if your roads are tolled.

Just yesterday I was trying to find videos about this, great timing!

Dealing with residential traffic is one thing, building an interchange for a large industrial park is the real challenge.

im so glad that u show interchange systems with actual lane maths. most channels show great designs and ideas, but forget about the most important part for eg. Vanilla based builds it helps so much to include lane math so u dont need traffic manger/lane manager ai. :D Great video

3:38 that is the simplest type of cloverleaf, and yes, the weave is a problem because it happens right on the main carriageway. the first step to solving the problem is to move the weave away from the main carriageway by splitting the highway into 2 separate, parallel carriageways and then connecting the slip roads to that secondary carriageway. there are many such cloverleaf interchanges in germany, traffic can flow freely on the main carriageway while the weave happens on the secondary carriageway the next step is to eliminate the need for the weave by switching the order of the lanes leading into the secondary carriageway. so when a car comes off the northbound highway onto the secondary carriageway, it finds itself on the right lane of that secondary carriageway instead of the left lane, so no lane change is required. problem eliminated. one example of such an optimized cloverleaf can be found in frankfurt, germany, right next to the airport, where the A3 and the A5 meet. that one is made slightly more complicated by the fact that another junction (A5 and B43) is very close. but you can clearly see that the lanes cross over each other in every leaf. and why the hell can't i post links to google maps???

It's so nice to watch your vids. Nice and even paced. Nothing fast so I have to go back over it (the worst) or, get bored and leave. Before I know it, the video is over, and I watch all the way through. Thank you.

I've been religiously using your SPUI parclo interchange in my cities. I love it! Amazing traffic flow and almost no traffic problems.

We love hearing your detailed explanation and everytime we get learn something about roads and intersections. You wouldn't belive but this topic is very exciting to me. Thank you for your great content. Keep it coming...

Your videos are very enjoyable ... like the Bob Ross of City: Skylines intersections :-) One thing I noticed in several of your videos: if you have a intersection with a traffic light like you have in the beginning of this video, you could force the cars going straight or right into the left two lanes and then allow right turns on all stopped sides.

My personnal totally unbiased opinion: This is your best video yet!! Especially that stack interchange looks cool!!

I hit Megalopolis in my city and can buy all squares now and I built a ring highway around my city. I used your single point parclo AS service interchanges and they work realy well. Thanks a lot.

It's always fascinating to hear someone talk about things their passionate about when it's a topic most people would take for granted.

Had the game for some years and didnt gave it much of an opportunity. Now I'm comming back to it and I'm loving it. Looking forward to more tutorials and videos like this so, new sub!

If not for vanilla, you should enable the TMPE option for not stopping at intersections at 2:00 for the turbo roundabout.

Cities Skylines' biggest drawback isn't the obvious lack of fine tunning you notice when you start modding it, it's the budget. The reason everyone is always full of great ideas for dealing with traffic is because everything there is so cheap. I mean, traffic itself is "nearly optional" when even a city with 50k residents can afford multiple subway lines. No reason not to have endless roundabouts (if you follow the Biffa school of thought) or nothing but colossal stack interchanges regardless of highway throughput. I even tried making a city once without a single intersection, just underground three way interchanges as far as the eye could see, and it worked without a hitch, with plenty of money to spare to increase budgets beyond 100%. What makes these videos great is that they don't offer utopian solutions, but that they have a common sense behind them

Thanks for the knowledge about the interchange. I now have some understanding of what the traffic is all about.

The best part of this is how the pedestrians are not even considered. Great work. Now build the dedicated transportation system for pedestrians.

I wished you talked about the interchange in your thumbnail :( This video was still very interesting and inspiring

Guy, since I discover your channel, I can't resist to watch new of your videos. You're really interesting and this way you have to explain it's just absolutely awesome. It's very inspiring and improve thinking about traffic management. Love from Belgium man, keep it up !

ive gotten pretty liberal with the modding of a stack interchange in one of my cities. used Move-it and Node controller to make the whole interchange be about 50% wider than just two highways passing over each other. looks really cool in a downtown environment.

Mound and I696 in Warren Michigan (just north of Detroit), a slightly contorted stack as a service interchange. I want to say we have a couple of full cloverleafs connecting stroads. We also have stacks were the lefts leave from the left and join from the left, M10 and I94 in Detroit. Quite a few of those also, but I think those are all system interchanges.

The art of turning left is a dark art. Build your grids in hexagons so people can only go “straight” or “right”. Then build subways that take people “left”. These directions don’t exist on a hex grid… but there is a direction that traffic flows easily. And a direction where traffic has to drive further to get to their destination. Make subways that flow along the direction where traffic would have to drive further. Then add some cargo rail in the same direction. Or maybe just separate homes and industry along that direction so trucks are disincentivized in driving through residential.

That’s so interesting learning about those system interchanges. I know about cloverleafs before, but not what stack interchanges were. Here in Fargo, there is an interesting interchange between i94 and i29 that is a partial cloverleaf and partial stack. Three directions are cloverleafs and one is a stack. I found it really interesting.

YUMBLtv: "Roundabouts aren't always the solution." Biffa: "And I took offense to that." Anyway, finally, a C:S RU-vidr who doesn't worship roundabouts as some sort of ultimate traffic panacea.

Have gotten a chance to watch yet, but saw that you updated and wanted to be sure to comment to satisfy the algorithm. Happy Thanksgiving. I'll let it play in the back ground.👍

i love how tidy those lane markings on the roundabout look

This channel really deserves way more subscribers. Top notch!

i feel like a nerd excitingly watching this and I love it

For getting off the highway, the parclo and dumbell are my go to if i got the place to use them and need to use both ways (dumbell for easy to build and quick to set up and parclo if i need to handle more traffic). They also look really nice when you look at them visually. But if i need to be really compact and i don't have much place, i'll use a three level roundabout. That thing can handle a lot of traffic (with slip lanes and all) and be really compact.

My personal totally unbiased opinion: Best video yet!! That Stack Interchange looks very cool! Keep it up!! -MaxFX

The best thing to do in Cities Skylines is to make the entire road system, actually just one, one-way road. Just one huge snake through the landscape. Sure, it'd suck to ACTUALLY have a real road like this, but the sims don't care. I like to think of them as always sight-seeing. "Here we go kids, thru the industrial part of town, on the way to school..." jk

Thank You, important for urban planning. I suggest you do a video on the complexity on New Jersey interchanges.

You are good at explaining things and have a nice calm voice good job 👌👍✔

2:16 I'm now so curious as to how the roundabout would perform if it had the same 4+3 roads as before and two straight-ahead lanes instead of one. (Literally just 'split' the middle lane into two to double the straight-ahead bandwidth and whether that would reduce the tailbacks at all.) I'm not saying the roundabout would perform better but it's not at all a fair comparison having a 3+2 turbo vs a 4+3 lighted intersection and saying the roundabout causes tailbacks. (Not a complaint at all I'm just curious what the results would be.)

Its important to note i think, that in City Skylines price of roads isnt as big of a problem as in real life. As much as a clover leaf is crappy, its real cheap whereas a 4 stack is extremely expensive like a loooot

You shouldve mentioned that you can combine intersections and roundabouts. Dumbbell intersections look pretty cool, they are easy to use and efficient, both ingame and irl. I know of one that is somewhat local to me (40 mins away). Its a nice change from all the regular intersections and interchanges.

I think a combination of the partial cloverleaf and over/underpass for through traffic will prove to be more efficient. I use such combinations often and have over 89% traffic flow in a city of over 250k.

Take your biggest most traffic intense road and build a bridge so the right side of the road can be on the left side. Take it around the outside of your city. Do the mirror of that on as the road exits you city and run that incoming road around the other side of your city… Now you have the worlds largest double diamond interchange, a very low conflict exchange. It also may look like an inverted roundabout to some. But whatever you call it, it solves many traffic problems cheaply.

I appreciate your take on roundabouts. They are useful, but are by no means a magic bullet.

5:50 The traffic light settings on the ParClo can be adjusted such that the surface road traffic coming off the overpass in each respective direction never has to stop. The ramps allowing a right turn off the highway can likewise flow freely if they get an additional lane on the surface street. If each onramp has two lanes initially, the right turn onto the highway can flow freely as well. The only stops are the surface street as it approaches the interchange from the outside ->

Us kiwis have perfected the art of turning left! We hardly ever cross traffic when turning left in New Zealand....

Cool video, but I think that by creating a diverse system of transportation (bus, metro, tram, etc.) will lower the traffic volume way much more effectively than an urban highway, but still cool video

My favourite intersection is definitely the cloverstack, best of both worlds!

My personal favorite is the single-point. I used that whenever I can because it's compact and looks good.

I would say i don't know why that appeared in my recommendations, but i can imagine (Thank you, motoway Matt kkkkk). But great video anyway. Super interesting

In your first example right turn traffic should have a green light at all times. Since straight through traffic is only two lanes and leaving streets have three lanes and right turn traffic does not conflict with any other traffic. Further optimization would be left turns with two lanes.

In the end it all comes down to the space you got and how much traffic you anticipate will be using the said road/intersection.

In the UK, from my experience, the primary junction/interchange used is a grade separated roundabout, though there is a great example of the stack junction you mentioned just outside Bristol where the M4 and M5 converge, it's honestly quite beautiful looking at it on google maps! :-P If you wanted to see the most insane junction in the UK though, it's the A38(M) joining the M6; Gravely Hill junction, also known as Spaghetti Junction! You could say, this is what happens when stacks go mad! :-P

the main reason cloverleafs were so popular is that they're probably the cheapest system interchanges. It's becuase they only have two relatively short overpasses were the roads crossover. the rest of the road is either at grade or can have the grade modified to support it which reduces concrete use.

I do feel like the roundabout could still improve matters if it is built larger. The benefit of a roundabout is it increases the number of vehicles passing through the intersection at the same time, but the relatively small roundabout you had, would probably only handle arterial road traffic. Obviously you don't want to stick a roundabout on a highway though. Common design in the UK as you probably know is to have a roundabout above the highway and have slip roads leading to/from the roundabout to the highway and connect your arterial roads to the roundabout as well.

This channel has convinced me that roundabout aren’t that great.

Though it's not perfect, the oval-about works pretty well as a service interchange. And it circumvents having two different roundabouts fairly close to each other.

what about the full diamond interchange? its smaller than the stack but still free flowing

Also putting stacks everywhere is unrealistic. I like realistic building in cities skylines, which mean the traffic flow should be as good as possible with a minimum budget. In my city with over 300.000+ I only use stacked interchanges at the cities entry's, everywhere else just traffic lights and some roundabouts here and there

Been looking at Google maps a lot recently for inspiration for this game, and looking along the east coast of America I see a lot of these absolutely enormous, spaghetti like monstrosities right in the city centers, I was wondering if you could maybe do a video covering these? Maybe going over the design principles and history behind why they're like this,, because they seem to exist counter to what you've described here regarding service interchanges. Thank you :)

I've become a fan of the single-point parclo. Great flow and only a single light to deal with.

Excellent video as always YUMBL Happy Holidays!

I’m surprised you didn’t pitch your SPUI service interchange, which is my go-to for all service exists. It’s infinity good.

We have only a single stack interchange in all of Germany, despite being known for our Autobahns. And it a rather useless Stack interchange. It connects Autobahn A45 with Autobahn A480 but A480 is just 3.6 km (2.2 mi) long. While a 2km (1.5 mi) extention to the south is considered. As a replacement, because the city where the stack is located is considering to demolish an elevated through road through the city, but the extention to the north is canceled. It's basically a stack for an service interchange, at the moment and for the foreseeable future.

The stack interchange isn't the only free flowing interchange, I actually like the dutch approach of having two leaves and only two overpasses, this way you end up with only one level of overpass, hence two levels total. I'd appreciate if you'd be able to show these types of system interchanges as well, I think they are a very cost effective approach especially when it comes to converting clover leave system interchanges into free flowing. I also actually like that their footprint is smaller since you don't need to overcome such massive height differences. What do you think about this approach?

You missed the standard British roundabout interchange, which is our stalwart service interchange (this is not a dumbbell) When they get congested, cover them in pretty traffic lights :)

I quite like the 3 layer roundabout for my interchanges personality although I have to try out that b4 clover

My favorite CS vanilla highway interchange is the windmill. Playing on console some of the more elaborate things are harder to do.

Learning a lot from your videos. Thank you

Can you not apply grade separation to the turbo roundabout plan to get something both compact and free flowing (albeit with sharp turns)? The idea would be that the roads would both be 3:3, the E-W arm would see inbound lanes 1 & 2 (of 3) elevated a little less than a full level (say 6-8m) on the approach, and the N-S arm would see inbound lanes 1 & 2 similarly depressed. You've got a half rotation of the ‘roundabout’ for each of these to return to grade, which should suffice.

I was just thinking I haven't felt personally attacked about roundabouts yet at the beginning of the video but it was just a premonition.

my personal favorite: public transit that carries 100 times the amount of people over these single occupancy vehicles. I use a mod where I can adjust the passenger count for each transit vehicle to be more realistic. 30 on a bus is vanilla, but irl if people are standing it can be around 45, etc

So Biffa is the round-a-bout person, CityPlanner is the waterpipe person guessing you will soon be known as the interchange person :D

I think the roundabout has to be linearly bigger to the amount of traffic going through it. The reason is that there have to be enough space on the roundabout itself to fit enough traffic. It basically have to fit as much cars on the roundabout as the timed traffic lights let through in one sequence :) (at least that seems logical from math point of view) Defintely roundabouts are not something you want to have in the center of the city on main roads if you don't have the space, but i think that you shouldn't have to have such traffic in center anyway :D

Awesome stuff. I love your videos.

Always loved the parclo since you inspired me to start using them awhile back but pretty sure your lights can be set up better

2:38 they can still turn left and right they will just have some “minor” damage afterwards

I really learn from this, great work thank you.

Good distinction to point out :)

Learned about innerchanges on the innernet.

Did you study civil engineering? Or did you just do a lot of research? As a civil engineer myself, your explanations are very good.

I am using the last one as my service interchange style.

Great video @yumbltv !!! Excellent explanations as always. Did you hear @city planner plays gave you a shoutout on his video he named the University in his beginner build tutorial yumbltv University.

I love your videos. at 2:46, the car random on the one side changes color lol

On the roundabout it was clear, that only moving forward vehicles were stacked, even the ones who turn left were ok. So I wonder, what if you tried the roundabout with forward overpass, that you demonstrated a while ago? Doing the overpass even just for one road would drastically reduce the amount of cars on the roundabout and might even help to clear the other road.

What about the following intersection. The left and the right side of the road are grade separated. Ramps occurring on both sides. I think a missed opportunity is that one side of the road never has any form of connection.

this makes me think back in simcity 2013. what a nightmare... anyways, just the other day i went all in on my first couple custom timed traffic lights for a few main intersections. Im trying to recreate the area where i live and there's mostly traffic lights so im really trying to make them work but i dont have a large population yet. (less than 20k) so far there is no problems. For me the traffic light is very satisfying to watch lol

Thanks for the great video! I have a question. How do you generate the desired amount of traffic on intersections for your videos? I've tried to find a mod that allows to generate an arbitrary traffic between arbitrary points on a map and had no success.

The best solution for the problem of left turns is to live in a country where cars drive on the left! :) (Makes right turns a problem though!)

Diverging Diamond Interchanges are the best. No left turns into crossstraffic anywhere which reduces crashes.

I would be interested to see you make a typical British service interchange, which is a grade-separated roundabout with ramped sliproads to get on!

The flaw with the roundabout at 1:24 is that you have single lane for each direction. Notice only middle lane on each entry is congested. The fact that the left lane is not means you have way more traffic going straight than turning left, yet you have only one lane for each. I'd say, allowing the left two lanes to weave both on entry and on the roundabout should increase its traffic throughput because traffic now centered on the middle line will spread over two lanes. Now, of course a roundabout with cars crossing will slow the traffic down compared to the further designs. But it doesn't have to be as bad as in your example.

Next you should show the Jersey Jughandle. The Jersey left! All Turns From Right Lane.

Does anyone use this game using actual city layouts and traffic patterns to see how they might improve traffic flows IRL?

This video will cheer Derek Zoolander up.

CAN YOU PLEASE DO A VIDEO ON THE MID-HUDSON BRIDGE IN POUGHKEEPSIE NY!!!!! Its a 1 of a kind intersection that they are asking nation to help fix

Now I kind of want to build the city the comment section deserves; one where every 4 way intersection is a stack interchange. An American style grid with nothing but stacks.