there are a few talk groups that can be heard over different sites other than their own ... for example, when I'm listening to the Lynchburg site I can hear Bedford Sherrif, Bedford Fire, Amherst Sherrif and a couple others ... I don't think you can hear Lburg PD from any other site than theirs tho ... I don't have my scanner with me bc I'm at work, but I can post some more "cross-site" talk groups later and, I'll actually be in Lynchburg this weekend so I'll take note of as many talk groups as I can that do this ...
edit: just wanted to comment on the fact that this system is at the very top of my list of favorite systems to listen to and monitor ... IMHO it is awesome and they did a great job on it
I think the system works like most wide area systems. In other words, if a mobile/portable radio "affiliates" with the system on a particular site then it will repeat all traffic for that radios selected talkgroup on that site. In other words, if Lynchburg PD is not normally transmitted on the Bedford site but a Lynchburg PD mobile unit drives through the Bedford sites area it will start transmitting the Lynchburg PD talkgroup. Each radio is set to "affiliate" with the control channel when turned on and channel is changed. That way the controller for that site knows which channels it needs to rebroadcast.
You hear some talkgroups on adjacent sites since they have mobiles/portables that are close to the border and therefore there are some units affiliate on each of the adjacent sites.
Anyway, that is the way it appears to work. I know that is the way Motorola wide area systems work.