The ABS system was invented in 1872.
Would it have been in use on the SP mainline Overland Route in 1885?
I have the feeling that you mean “Automatic Block Signaling”. You might want to correct the title of the thread to get more responses.
http://www.lundsten.dk/us_signaling/signalbasics/
Unless you are talking about the area around Chicago, it seems unlikely that it would have been in use on the SP in the 1800s. For the most part, this would have been “dark” (unsignalled) territory in that timeframe, with Timetable and Train Order for traffic control.
I don’t know the details of the SP in the 19th century, but these systems were very expensive in the early days and would have been used only where there were very high traffic volumes. SP was one of the leaders in development of ABS, but I don’t think it was in broad use until the 20th century.
Byron
Model RR Blog
And adding that it is an electrically powered system. I doubt that there was a reliable source of power over the 1000 miles of rugged wilderness that the SP’s route went through.
Dave H.
First known patent for an automatic block system was issued in 1848, in England. The first prototype automatic block system appeared in the U.S. in the 1860s. The first “successful” automatic block signal was tested on the Erie in 1870, and the first ABS system that can be regarded as permanent was installed in 1872, also on the Erie, at Irvineton, Pa. During 1876-78, small installations were made in New England. It took another 15 years for the technology to be sufficiently improved to achieve wide-spread adoption. By 1900 there were about 2,000 miles protected by ABS in the U.S., and beginning that year the technology spread very rapidly.
I can’t recall if SP had any disc-type signals – UP had about 10 miles of Hall signals, which were on the Lane Cut-Off as I recall – but the Harriman signaling program began in 1904 and by 1909 the Harriman System had about 5,000 miles protected by ABS. The Harriman lines standardized almost immediately on the US&S Style B semaphore wired on the “Overlap System” and did not convert to Absolute Permissive Block until the 1930s. There were some GRS lower-quadrant semaphore installations in a few places and the LA&SL used Federal and GRS signal equipment until the 1930s. The Harriman lines usually purchased GRS interlockings for some reason.
Almost all ABS systems until the 1920s were 100% battery powered. The signal maintainers among other duties traveled their section each day and charged low batteries. Some battery powered systems were constructed in the 1930s in areas with no commercial power.
RWM
ABS didn’t last too long because APB was much safer. ABS could only prevent a collision from the rear but not protect from head on. Absolute Permissive Block made it safe for opposing traffic to travel on single track.
The Old Dog does NOT know when ABS came in.
But it can point out that using a manual block system might add interest to your operating sessions.
Have fun
PS You might search the books section of Google, there are several books on signal there that can be viewed or downloaded.
xPD:
David Marshall has a lengthy discussion of MBS for a model railroad in MODEL RAILROAD ENGINEERING. It’s really neat, but probably best adapted to a model RR that is operated on the section control plan, or with roaming engineers and stationary towermen.
Basically, each station has two buttons and two bells, a control for his home signal, and a lockout for the next signal upline. The buttons are used to ring the next guy’s bell for signal clearance, and the bell used to receive this request from the upline station, or to receive the acknowledgement from the downline station. When it is received, the home signal is cleared, but it will only actually clear if not locked out by the next block station. Signals are always at STOP and are briefly cleared, if authorized, on a train’s approach.
(I’m thinking this is pretty close to how MBS actually worked in England, but I’m not sure.)
It gets a little complicated for multiple directions of travel, and I think buzzers might be less strident, but it would be cool to see it in use.
APB was installed on a lot of single track mainlines. Many times it was called ‘auto dispatching’. ABS for the most part was installed on double track(which had the higher density) before APB was conceived. There is still a lot of ABS installed(the ex-CB&Q double track from Prescott, WI to Savanna, IL). IIRC, the ex-NP mainline has a lot of ABS on the double track portions as well.
APB does provide better protection as all opposing signals between the sidings will ‘tumble down’ to red.
Jim Bernier
H:
I think the “overlap system” mentioned might have been a way of addressing this problem with ordinary 1-block-spacing ABS. This system either separated the trains by 2 successive stops (so that both opposing trains would end up approaching the same set of signals prepared to stop) or divided the blocks in two parts, so that the home signal for any given block would remain red until the train had left that block and traveled to the second part of the next block. The advantage of APB over these is that you could run safely with shorter spacing between trains.
Edit: And also that you’re taking the whole length of single track between sidings into consideration. I suspect the real issue with MBS on single track wasn’t “Aw crap, we are going to hit that train”, because there were ways around that, but “Aw crap, now one of us is going to have to back up to the last siding.” (and of course the traffic-density thing)
Yup!
On railroads APB and ABS are used virtually interchangeably. Many rule books and timetables never mention APB (for example the GCOR used by almost every railroad west of the Mississippi), although the “ABS” signal systems are actually APB.
So while there is a technical difference, from a rules prespective, ABS is the same as APB.
Dave H.