Cities: Skylines
119 Achievements
2580 XP
60-80h
Epic
Safe City
Keep the crime rate under 10% for 4 years straight
15 XP
13.0%
How to unlock the Safe City achievement in Cities: Skylines - Definitive Guide
Just keep a eye on your crime rate and add police stations when needed also at one point you can add a policy called "harsher prison sentences" I would recommend adding this if your at that point. A lot of the time the cop cars seem to be stuck in traffic I would recommend buying roundabouts so the traffic can flow. The amount of people who are uneducated determines your crime rate so make sure every citizen has been in a elementary school or higher.
When you click on your Police Icon, you will see the current crime rate at the top left Corner. You want to ensure that you have as much of the roads green as possible and the houses blue. Red houses are at risk. Once you have a crime rate under 10% just sit back and wait and just make sure you dont cross that threshold.