Split Rail Derail Question

[NW Mailing List]

Herr Matteos von Gootmann asketh about split derails at interlockings.

The answer to his question is this: In the early days, before Automatic Block Signaling was developed as a method of train control, it was possible for a train to encounter a Stop Signal at a diamond without having received any warning on a "DISTANT Signal." And remember, prior to the late 1890s, most freight trains were hand-braked, and prior to 1906 there was no limitation as to how man yours a train crew could be on duty - so you can extrapolate on these circumstances from there.

Under such conditions, "split details" were common protection for railroad crossings at grade.

After the introduction of Automatic Block Signaling and the installation of DISTANT Signals for interlocked crossings at grade, split derails as a means of protection at these locations tended to go away.

I have never seen a discussion of this matter in the published trade literature, but it is pretty easy to synthesize what was going on in the industry.  The advent of Automatic Block Signaling changed a lot of things in railroad operations... even Train Orders !

Somewhere in the 19-teens, the ICC came out with a document which was called RS&I, and I think that stood for Railroad Signals and Interlockings. This was the ICC's book of standards for what the railroads were required to do, and how they were to do it. With the publication of RS&I, the locations where split derails were required became a matter of Gubbmint say-so, and no longer a matter of company policy. I can recall from various meetings I was in during the 1980s and 1990s, the Signal Department people still referring the the requirements of the RS&I. I think those standards were eventually incorporated into the Code of Federal Regulations Title 49, Title 49 covering railroading operating practices. You can get the CFR 49 on-line and read away until you fall asleep in your easy chair.

Also, you may want to check the N&W Standard Plans for M-W and Signal Department (if they are available anywhere.)  Those plans will give you the N&W's protocols and requirements for derails protecting railroad crossings at grade.  And the nice thing about standard plans is that they have a block at the bottom for notes indicating the dates revisions were made, and often a note about exactly what was changed.

We Horse-and-Buggy Pennsylvania Dutchmen send fraternal greetings to Mr. Gootmann out in the Kingdom of Ohio, Diocese of of Greater Metropolitan Columbus.  And I shall now return to my own little delusional turnip patch of 1840s research...

        -- abram burnett
Developer of Turnip AI and Software