The "issue" (not that it's necessarily an issue) with the two separate sites is that the same talk groups that are on the Cincinnati site are also on the Hamilton County site, and vice-versa, the majority of the time causing each talk group to use two frequencies, one on the county site and one on the city site. Being that the Hamilton County site also has several talk groups on it from outside agencies the site loading on the Hamilton County site can get rather severe at times. When they fire the all county broadcast they light up 4 of the 20 channels on each site, 8 in total, to broadcast the exact same radio traffic. If they had a single Hamilton County site (this site already has coverage of the entire county) with 30 channels (adding 10 channels from the city site) the need to use multiple channels to broadcast the exact same traffic would be reduced to 1 channel and they would have 10 more channels to help with the site loading.
I'm sure they're aware of all that, but have decided it's acceptable. The problem with jamming a large metro area onto a single site, no matter how many channels, is that if it crashes, there's no acceptable backup available.
I know that Columbus City and Columbus MARCS (previously Franklin County) back each other up to some extent by plan and design, and I wouldn't be surprised if Cuyahoga County and City of Cleveland do so as well.
And a 30-channel site wouldn't necessarily solve loading issues; the Columbus MARCS site is 30 channels but I've seen it get awfully close to max density on a number of occasions. If all of the City of Columbus site users were brought onto it as well, there would certainly be some occasional loading issues. Better to spread the load out.
I do tend to agree with you on this but isn't this why we have site trunking/fail soft/conventional back-ups?
While I don't know the exact site failure plans for the Hamilton County and Cincinnati sites I do wonder how having both sites carrying the same radio traffic would effect site failure. I do know the conventional back-ups use the same five frequencies (8 CALL/TAC's) for both the county and city.
Both site trunking and failsoft do you no good if the site itself crashes.
In the event of site trunking (or failsoft) the radios automatically search out a site which is still in wide-area trunking. In the case of Hamilton County, certain radios are probably set up to prefer their respective site, but if that site fails or goes into site trunking they'll automatically jump to the other site.
In failsoft, you lose most of the capacity you gain with trunking. Each talkgroup is assigned a specific frequency to operate on and it doesn't really work unless a radio is always operating on a specific site. Most radios aren't even set up for it.
With a networked system failsoft is relatively unlikely since you have multiple layers of control; if the master site fails the zone controllers take over, and if the zone controller goes away each site controller takes over. It's only when all that has failed that a site will go into failsoft.
Conventional backups are fine, if the county not only has them and has trained everyone to use them when necessary, but they're an absolute last-ditch thing; there's still the issue of very few channels being expected to handle all the traffic of a major metro area should it become necessary so having redundant sites is much more preferable, even though it might seem wasteful.
