Here is the full list of all 18 911 Operator achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Awarded for working in 15 different cities.
Complete the game on Expert difficulty
Awarded for long service (30 duties)
Awarded for finishing the campaign
Complete the Single City Run
Awarded for reaching high experience level (any team member)
Awarded for finishing 3 duties in a row without any death or major mistakes (less than -3 reputation)
Awarded for gaining 100 reputation points on one duty
Awarded for special tactical skills (gather 3 police teams before shooting starts)
Awarded for keeping the roads safe (Resolve 50 driving reports)
Awarded for resolving a case despite death of your team member
Awarded for resolving 50 fire or technical cases.
Awarded for saving a life by giving proper first aid instructions
Awarded to those wounded or killed while serving
Awarded for saving 50 people by driving them to a hospital.
Awarded for a sense of humor ;)
Complete a duty without overtime on Hard/Expert difficulty
Awarded after finishing the training