I spotted these vintage views of Pittsburgh from the mid-to-late 1960s
http://www.youtube.com/watch?v=8NkDPWv0VrA (http://www.youtube.com/watch?v=8NkDPWv0VrA)
http://www.youtube.com/watch?v=RpS5ess9VNc (http://www.youtube.com/watch?v=RpS5ess9VNc)
The Wabash Tunnel (http://pittsburgh.pahighways.com/busways/wbusway.html), which was converted for use as a HOV facility, was intended to be used for the SkyBus project. The footage there is from the test track in South Park.