I think that for major incidents such as major fire or pile up or even calls that require 5 or more units you should have to send what is called and ICU vehicle (incident Command Unit) this unit keeps tabs on what vehicles are at that incident and manages how the incident is run. the ICU is usually a bus in the uk or can also be a van which has an retractable tent that sets up when it arrives.
I think that this would be a good addition to the game.