Cities: Skylines – Tips on How to Improve Traffic Flow (Problems&Solutions)


Welcome, visitors. In this guide, We try to explain How to Improve Traffic Flow in the Cities: Skylines game. There will be many tips on how to solve traffic problems in this game. So we pick up many pieces of information from several sites for you. We hope that this guide will help you.

Why Do Traffic Jams Happen?

The first step to solving a problem is to understand it. Knowing is half the battle.

Traffic jams are caused by one thing, cims. The more cims you have in your city, the more vehicles are on the road, and the higher the chance a traffic jam will occur. As an aside, when you dive into the details of traffic flow theory, the number of variables makes things appear complicated. We do not need to know the game’s pathfinding algorithm; just know that more cims equals more traffic jams.

Traffic jams appear when the amount of traffic through an area exceeds the carrying capacity of the road layout in that area. If a road layout can only handle, say, 20 cars/trucks per in-game day and it gets 40 cars/trucks, well then, a traffic jam occurs. In the screenshot below, you can tell where a traffic jam will start. The circled 4-way intersection is a hotspot for cims coming and going.

The road layout is not “bad”, per say; it is just that current demand exceeds its capacity to provide. The fact that we cannot “see” what maximum carrying capacity a particular road layout can handle is what leads to our frustrations (and thoughts that the game’s traffic simulation is broken).

Side Note: Where Do They Occur?

When you start off building/growing your city, the first location for a traffic jam is likely the highway interchange that brings your first cims and goods into your city. Obvious, I know. After this site, the next traffic jam location is anyone’s guess.

Traffic jams are an emergent behaviour over time. It happens in real-life cities and in your game cities. It is part of the growing pains of any healthy city.

For the sake of sanity, I recommend not worrying about where they will occur. 🙂 Just react to them when they do occur.

Side Note: Traffic Jams Are Bad, Right?

Ummm, no. As frustrating as they are, traffic jams are a good thing. Before you flame me, let me explain.

Traffic jams indicate a demand for goods/services in a specific area. This is good because it indicates growth in that area. And you want growth in order to collect more tax money for your city’s treasury.

Learning to manage this growth is at the core of reducing traffic jams. That is, think of reducing traffic jams as another task in managing a growing city. I say “reduce” and not “eliminate”. You already know how to eliminate traffic jams. It is un-fun.

Tips on Improving Traffic Flow

Here are some general, high-level tips to improve your gameplay. They are in no particular order of importance.

(1) is easier said than done. Learn to appreciate that the game’s pathfinding algorithm is exposing a pattern that needs addressing. Your job is not to eliminate traffic jams entirely but to reduce them.

(2) saves you stress and frustration. Just know that traffic jams will occur as your city grows. Focus on growing your city. Let traffic jams show up in their own time.

(3) may look ugly/inelegant. But if it gets the job done, that is all that is important. Function over form.

A Case Study – An Example Traffic Problem and How to Solve this Traffic

(4) is about looking at persistent problems instead of noticing temporary ones. Sometimes traffic jams will untangle themselves with no help from you. As you grow your city by laying down new roads or re-routing old ones and by zoning and re-zoning areas, you change traffic flow. These changes take time to manifest themselves as potential problems. When traffic jams become so big they cannot be ignored, it is time to stop all changes and just watch. Let the game run for a few in-game weeks/months. See if traffic jam site(s) clear up by themselves. If not, then you know you have a problem that needs addressing.

A Case Study – An Example Traffic Problem and How to Solve this Traffic

We will first observe the origins and destinations of our traffic to find the root cause. Then, we will adjust routes to achieve load-balancing for our roads, relieving the city of congestion.

The land usage of example city is as follows:

The islands completely separate Residential, Commercial and Industrial lands. Red lines are highways linking them.

The Problem

We notice a large traffic flow on the highway interchange south of Commercial zone. Lots of right-turning traffic clogs the entire bridge connecting to Industrial.

Observation of Traffic

Step 1 is to determine the origins and destinations of traffic. Observing the land use plan for this city, the sea-spanning highway is the only link between Industrial and Commercial. So there’s bound to be lots of traffic on this route. Let’s go upstream to see where these car come from…

The traffic jam continues all the way onto the industrial island. Lots of trucks trying to get on via the only service interchange on the island. But notice the traffic in red circle. They are clearly not industrial traffic. Where are they from? Let’s trace up.

This is the bridge spanning Residential and Industrial islands. Plenty of traffic heading towards the Industrial island. Most of them do not exit at the Industrial island interchange, so they are obviously heading towards the Commercial zone.

And those foolish residents never stop driving towards the Industrial zone, even when the bridge between Industrial and Commercial is fully clogged.

Our (simple) root cause analysis is now complete. We conclude that Residential traffic headed for Commercial zone takes the Red highway over Yellow highway because it is slightly shorter. The combined traffic from Residential and Industrial clogs everything.

Of course, with better public transport, there shouldn’t be this much traffic between Commercial and Residential. But to make things interesting, let’s constrain this problem by making transit unavailable. The car-loving mayor Rob Ford is in office!

Another constraint we will place for this problem is land use planning. We shall not modify the existing usage pattern for our islands, for it is prohibitively expensive in this debt-crippled city.

The only option left is to build new or modify existing roads. We can start by optimizing traffic routes.

Red circle is the main destination of our bumper-to-bumper traffic. Most cars are clogged all the way along yellow line. We can try building a new exit ramp to connect highway with the city.

Like so. A three-lane one-way off ramp diverts traffic on the highway. A three-lane road is chosen because it gives one lane for each of three directions (see section Route Optimisation above). Let’s see if it works.

Initial results promising. The congestion seems to be easing, and most traffic from the right side exits through the new off-ramp. Let’s stay here just a bit more, make sure things settle down into steady-state.

This off-ramp seems to be “too effective”. Everyone ends up choosing this route, essentially moving the endpoint of our congestion from the Commercial zone service interchange to here!

The heavy traffic on our “off-ramp” is quite sad. We didn’t solve congestion… only moved it.

It should not want to be used this ramp by everybody, only people whose destination is close to the ramp itself. To discourage traffic, let’s try downgrading this three-lane off-ramp to a two-lane road.

The traffic pattern adjusts itself again after the modification… Again we wait until things reach equilibrium.

And it’s Super Effective! Most traffic are back on the highway, and only a portion of them chose this off-ramp.

And the traffic at off-ramp end is also very good. Turns out we didn’t need three lanes anyway.

The service interchange also has better flow, now that some of the traffic is diverted off earlier.

Moving back to the Industrial zone, the situation hasn’t improved. This is because cars from Residential continues to pour into this already congested gateway for Commercial. We need to solve the root cause — Residential traffic shouldn’t be here.

Let’s go to the on-ramp for Industrial zone, on Residential island. The most barbaric way would be to simply remove that on-ramp, so we must do that now. After the demolition, drivers on the roundabout discovers that they cannot go this way anymore, so they start finding another alternative route to the Commercial zone.

Now they are all moving on the yellow highway, as originally intended. Only a small portion of them still use the red highway, but it is a small amount, not enough to cause major trouble.

Check it out! This is the bridge spanning Industrial and Commercial zones now. Much better. In our example, you can also downgrade the bridge between Residential and Industrial islands to achieve a similar effect.

This is the ending of the guide. In this guide, we tried to show how to improve traffic flow, how to solve traffic problems and show many tips on to solve traffic issues in the Cities: Sklines game. I hope it will help you. If there is wrong or you have suggestions, please let’s know and comment us. Have fun.

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