Every game of Cities: Skylines begins with a single map square and a highway connection. Players can build streets that branch off from the highway at first, but they can't touch the highway itself.
That all changes when players reach the Boom Town milestone. At this point, players can build their own highways and demolish or reroute the highways that already exist on the map squares they control. This gives players a lot of power over the traffic flow of the whole region, and if they're not careful they can create a gridlock situation that extends to the edge of the map.
Basic Highway Intersections
Highways have special properties compared to the other road types in Cities: Skylines. First, highways are always one-way roads, and so players must build them in pairs to move traffic in every direction. Second, highways have a high speed limit that allows vehicles to move quickly across them. Third, highways don't create any zoning squares the way other roads do. Finally, there are no stoplight intersections allowed on highways.
Another road type that unlocks with highways is the highway ramp. These ramps are also one-way only, and they're only one lane wide, but they give vehicles the same high speed limit as a regular highway. This makes them useful as merging lanes for highways, but any type of road can intersect with a highway. This means players can upgrade highway ramps to one-way roads with two lanes, four lanes, or even six lanes if they need extra space for merging vehicles.
Highway Connection Tips
- It's very possible for players to create a four-way intersection that crosses a highway. However, doing so can cause a lot of problems since it will force highway traffic to slow down or even stop as cross traffic tries to work its way between the speeding cars. Players should always use bridges or tunnels to keep off of highways as much as possible.
- When it's not possible to avoid highways, use roundabouts and one-way merging ramps to keep traffic moving.
- To connect both highway directions to a road on one side, players should use overpasses and tunnels to get across both highways. If a potential overpass turns red, then the pillars it sits on would stand on another road. To avoid this, players should either extend the overpass farther to make the pillars move, or they should try to get a better angle to cross the roads.
- The sharper a turn is, the more vehicles will slow down to take it. Players should use the curved road tool to make highway turns and merging lanes as smooth (and fast) as possible.
- The three-way intersection and cloverleaf intersection that also unlock with highways are templates, nothing more. Players are freely able to design their own versions of these intersections based on whatever traffic demands they have.
- Players should never build residential or office zones close to highways. The high speed limit creates a lot of noise pollution, and even the sound barriers (unlocked by the Busy Town milestone) can only help so much. Noise pollution isn't as bad as regular pollution, but it can still prevent these building types from upgrading (and thus providing more tax money).
- If traffic slows down in a certain neighborhood, players may want to build a longer off-ramp so the slow traffic stays off the highway.
Cities: Skylines is available now on PC, PS4, PS5, Switch, Xbox One, and Xbox Series X/S.