GO Bus service consists of a combination of routes, many of which stand in for train service when it is not operating and/or which extend the reach of train service to communities beyond their termini. Other GO buses are independent of rail services, such as the Highway 407 series of routes, which provides an orbital-type service that encircles Toronto proper and makes connections between all train lines. There are also routes that serve Pearson International Airport, seasonal destinations such as several colleges and universities. The vast majority of GO train stations have connecting GO bus service, of which almost all the exceptions are situated within Toronto proper. There are also 16 bus terminals served by GO buses, many of which provide local transit connections, as well as intermediate stops and ticket agencies.