For the MSP barracks...
Perryville (plus the 151.04 SHA/MSP translator - horrible audio and all)
also keep 155.73 vehicle repeater freq handy with no PL - if you hear them here, you're close....
And for the State Highway Admin
You will need a good mobile antenna for the lo band comms. Most units are using recut CB type whips or loaded verticals and either 50 or 100 watt mobiles, so it's not so easy to catch them.
Finally keep 39.62 handy. That is the PMARS retransmission freq, and can easily be heard starting in AA county and points toward DC.