The switchtender at Brighton Park operated a number of semaphore signals mounted on a bracket mast and a regular mast. The blades were directly operated from the mechanical lever frame in the tender's shanty via a system of pipelines and cranks. All trains approaching Brighton Park had to come to a full stop. The tender would then signal permission to occupy the crossing via the semaphores. Each semaphore represented a specific track and direction. The tender was also responsible for lining the switches north of the crossing for NS trains to cross the CSX main to then get to the industrial spur via a diagonal track.
Here is some more information about Brighton Park at the Chicago Rail Junctions page, and some additional photos courtesy John Roma.
Anyway, the reason Brighton Park hung around for so long in this archaic configuration was because the three railroads involved could never agree on who would pick up the tab for interlocking the crossing. Furthermore, no railroad wanted to cede dispatching to one of the others and risk getting screwed over priority wise. The tender at Brighton Park routed the trains on a FCFS basis, except for scheduled Amtrak and Metra trains which were given priority.
Eventually Norfolk Southern was responsible for the rebuild and took over dispatching the crossing. The other driving factor was that the Brighton Park diamonds needed replacing and the whole crossing had sunk down into the roadbed over the past 70 or 80 years and needed to be completely re-graded.
I decided to hit up Brighton Park early Sunday Morning after staying in a hotel with Pigs in the Loop. We got out there around 9 or 10 am and the weather couldn't have been better. We were not alone. A spike of railfans had already gathered, some driving in from as far as Toronto. There were also construction crews doing their thing for the July 6th rebuild date.
Anyway, I should probably cut the chit chat and cut to the photos.
You can find them all here:
First we have Brighton Park as seen from above from the adjacent CTA Orange Line. New cantilever signal is in the foreground next to the CTA substation. The BP shanty and semaphore bracket is behind. You can see the diamonds and an NS freight waiting for clearance to occupy the crossing.
Parting shot of the tail end of the eastbound intermodal clearing the crossing.