Cities Skylines Transit Systems Guide 2022 – How to Make

Citizen happiness is essential for your city, one way you can keep your happiness high is to make sure to keep your noise pollution low. We can accomplish this by using the roads with noise reducing properties; these roads are unlocked at certain population milestones, so make sure to upgrade your roads to these types as soon as you can.
Using these roads will keep everyone happier, but beware, they do cost more.

Keeping an effective flow of traffic is essential, so here’s how

Highways: You may be tempted to not use highways in your city, but if you use them right, they can be a valuable resource to you. To exit off of a highway, build your roads in a bridge over, and add the appropriate ramps
Busy Intersections: Sometimes, an intersection will cause a lot of traffic jams. The solution may be a roundabout. Roundabouts are very efficient intersections, so you may want to use them in the middle of your city where you have a lot of traffic.
Road Layout: When you plan your roads, you should make sure to have larger roads running throughout the city, delivering traffic onto progressively smaller roads. Making a grid of squares may be your first idea for a city layout, and while the most space efficient, it isn’t necessarily the best option. another space efficient way is to use larger blocks with a roundabout in the middle, laid out in a weave pattern. the system is completely modular, meaning it can be as large as you want just by repeating this pattern.

The key to a successful city is a good public transit system. One approach to making a transit system is to use different types of transit for a different scale. This means that your large train network will deliver passengers onto an intra-city subway network, which runs between areas of the city which each have their own bus route.
In this image, the orange line is a train route, the blue ones are busses, and the green one is a subway.