Installations of the signal system
My first installation of the APB signal system was my CTC-controlled lap siding Hazeltine, in N scale and built to FREMO americaN module standards. It was built during fall 2006 and had its debut at the 4th americaN weekend in Waiblingen, Germany in April 2007. Since then, several betterments have been done, including logic, APB interface, ... And since then, fellow model railroader Oliver Hampel has worked on bringing signaling to his own Fremont Branch junction.
The October 2009 Lauffen am Neckar, Germany meeting saw a CTC-controlled stretch between and including Hazeltine and Fremont Branch, with one APB intermediate signal in between. It was a real funnel, but CTC helped boost capacity, so everything went smoothly (we normally operate with TWC).

Lap siding Hazeltine (FREMO americaN)

East Hazeltine signal showing "Approach"
Hazeltine has three control points (East Hazeltine, West HT, and Center HT) and three MRBus controllers running CTC control point software 1.2.

Hazeltine seen from a higher position
If you use this system or a derivative one, I'd be happy to post some information about it. E-mail me at signals (at) us-modellbahn.net.