Questions on MTH PRR Signal Bridge

[FJ and G]

Guys,

My close friend purchased the MTH PRR Signal Bridge and has a couple questions. Can anyone help? Appreciate it!

One of the accessories I purchased is the MTH Pennsylvania RR Signal Bridge. It comes with two signal lights, but there are provisions to add two more.  So, here's my question:  Since the signal bridge is for dual track, shouldn't there be four signal lights---so each track has a signal for trains running in either direction?  I know some RRs just ran traffic in one direction on the main line, but I can see where I will want the flexibility of going both ways on mine.
 
MTH offers added bridge lights for the spare sockets on the top of the bridge. I purchased two MTH infra-red detection units to operate the lights, planning to use one to control the lights for one track block and the other for the second line. There should be enough room to mount the detectors between the tracks, each facing its own track so they're not activated by a train passing on the opposing track.  (Does this make sense?)  What do you think?