I'm in a hotel across the street from Cal Expo, and let the computer log all night last night.
453.800/458.800 PL 131.8 Cal Expo(Need Help to ID)
Sounds like staffing/administration. Some transportation of entertainers, various errands, etc. No unit numbers, just people calling each other by their first and last names. Also some scheduling information of entertainment. I'd feel pretty comfortable labeling it as "Administration/Entertainment"
453.975/458.975 PL 141.3 Cal Expo(Need Help To ID)
This sounds like maybe a trolley or a tram? All discussions involve making loops, picking people up, dropping people off, etc. I'd feel pretty comfortable labeling this one as "Transportation."
Police/security/parking are all correct as indicated previously by others.