Pittsburgh and the rest of Allegheny County use conventional UHF, VHF frequencies. Quickly for the city of Pittsburgh they use :
PD Ch. 1 - 453.100 PL 186.2 - Roughly downtown and inside the rivers
PD Ch. 2 - 453.250 PL 186.2 - Roughly South Side, North Side, and out side the rivers
PD Ch. 3 - 453.400 PL 186.2 - Roughly Oakland and east
PD Ch. 4 - 453.500 PL 186.2 - Index, Traffic, Tows
FD Ch. 5 - 453.700 PL 186.2 - Fire dispatch. Fire operations for all calls not working fires.
FD Ch. 6 - 453.850 PL 186.2 - Fire operations. Used for all reported or working structure fires.
PS Ch. 7 - 453.450 PL 186.2 - Public Safety. Command Post, Special events, and tac channel
PS Ch. 8 - 453.950 PL 186.2 - Police, detectives
EMS Ch. 9 - 462.950 PL 100.0 - EMS Dispatch and operations
EMS Ch. 10 - 462.975 PL 100.0 - EMS secondary channel
Pittsburgh DPW, water department, housing authority, animal control, refuse, and Heinz Field do use an analog TRS. This system uses two fleet maps. It is worthwhile listening to during Steeler games.
Pittsburgh also has a few simplex frequencies that get used from time to time.
For more info on the Pittsburgh TRS or the rest of Allegheny county try
http://mysite.verizon.net/k3fss
That should get you started,
Frank K3FS