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Wednesday, September 13, 2017

A British Style Tower In Illinois

In Europe, mechanical signaling is still quite common.  Paired with the manual block system, all or nearly all-mechanical interlocking towers control thousands of miles of main line track.  However in North America, the all-mechanical tower, that is with semaphore signals controlled directly by levers and pipeline, is virtually unheard of .  Yes examples can be found at drawbridges and diamond crossings on low density track, but the difference is quite stark.  Part of the reason is the general incompatibility of automatic block and mechanical signals.  Manual block was much less popular in North American than in Europe.  The other reason had to do with a number of ICC regulations that required signals to be interlocked with train detection (read track circuits) and that signals be electrically interlocked with point detectors.

You can imagine my surprise when I discovered Neilson Jct in Neilson, IL to have a set of fully mechanical signals controlling a manual block style junction with non-Restricted speed movements.  Now RR Signal Pics does a great job providing basic details about Neilson, but I just wanted to not only call attention to that page, but also to a set of videos that have been on Youtube since 2011, but due to poor use of keywords, does not appear on most interlocking tower or signaling related searches.

For a single switch between two secondary tracks, Neilson has a surprising number of levers.  First, just like in British practice, each former C&EI distant has its own lever.  Second, each of the southbound signals are connected to derails which also come with a facing point lock.  Finally, the 12 lever operated a mechanical timer that I assume provides approach locking in the absence of track circuits.

The northbound home signal handled the route route selection issue by having two semaphore heads, each controlled by a different lever and indicating one of the two routes.  Of course the straight route semaphore was for the C&EI and the lower diverging route semaphore for the BN.

Aside from the British style of operation, what really puzzles me is how such a tower survived up through 1989.  Checking Google Earth it appears the single junction switch was replaced by a hand operated type and that the line is un-signaled.

Basically just watch the 7 videos and read up on the RR Signal Pix page. I'm just trying to call attention to an historical oddity that is in need of some help with discoverability :-)


  1. Guess I do need to update my website with the youtube links rather than the website attempting to play the video off the server. Thanks for the shout out. As always Rock on!

    1. Whomever re-uploaded the videos forgot to include #6. But yeah, Youtube is the way to go for video, especially if you are paying for data transfer :-\

      Do you have any more info on why that tower was there/still in service and how the C&EI was operated?