Talk:Centralized traffic control

General Railway Signal Company, and their "NX" CTC system??
First of all, what has happened to GRS, and who is currently producing their NX CTC cquipment. I've looked, and can't find anything on the net that shows that they ever existed, and yet I know better. After all, GRS's NX system was the first practical CTC system on the planet. SSG Cornelius Seon (Retired) 21:14, 6 August 2006 (UTC)


 * General Railway Signal Co. of Rochester, New York, USA, is now a part of Alstom Signaling, a division of Alstom Transport.


 * The statement that "GRS's NX system was the first practical CTC system on the planet" is inaccurate, as the company had launched its first CTC system in Ohio in 1927 &mdash; a good decade prior to GRS's first NX installation, or that of competitor Union Switch &amp; Signal's "Union Route" system. The traditional unit lever-based CTC systems were much more prevalent than the route-oriented NX and UR systems because of the expense of the route systems.


 * Modern North American office control systems are nearly all CRT-based and most allow selection of an extended route (akin to the way NX systems worked) as well as allowing control of individual appliances. So while these use similar principles to NX machines, the logic is all in software rather than being wired networks composed of electromechanical relays as in the original systems. So there's really no one making GRS's original NX systems; the nature of control systems has evolved so radically over the years, that the only common trait between the 1930s systems and today's is conceptual. &mdash; JonRoma 23:00, 30 August 2006 (UTC)

Suppliers (was Commercial implementations)
So what constitutes a CTC system &mdash; the [office] control equipment? The trackside equipment? The operating rules that function in conjunction with the other elements of the system?

Personally, I view the list of suppliers as less relevant to this page than would be a detailed functional description of CTC systems &mdash; after all the same companies make a variety of other railway control equipment like highway crossing protection equipment, wayside signaling, cab signals, etc., all of which are orthogonal to whether a line is under CTC control or not. Probably deserves to be in a separate article ("Railway control system suppliers" or some such). However, given that the CTC article is little more than a stub, I would view a separation to be ill considered at this time. &mdash; JonRoma 23:25, 30 August 2006 (UTC)

Dark Territory
Although CTC strictly speaking implies that the central office has control over the field devices, today's railroad dispatchers usually monitor and control dark territory as well as CTC. It may be worthwhile to discuss dark territory topics like Dark Territory Control (DTC), Track Warrant Control (TWC), Positive Train Control (PTC) and the various operating rules (GCOR, NORAC, CROR) in this or related articles.Truthanado 03:31, 21 March 2007 (UTC) 03:30, 21 March 2007 (UTC)
 * There is already extensive discussion (some of it courtesy of yours truly) in the North American railway signaling article, especially in the Modern signaling in the U.S. section. I'm not sure that it needs to be duplicated here. cluth 04:58, 7 April 2007 (UTC)

Moving vs Fixed Block
This article currently describes fixed block signaling principles. Though used more in transit systems, moving block is becoming more common in railroads, and this might be a worthwhile additional topic in this and related articles.Truthanado 03:31, 21 March 2007 (UTC) 03:30, 21 March 2007 (UTC)
 * AFAIK, moving-block signaling is not in (widespread) use on any major North American railroad (transit systems excluded). And in any case, moving-block systems are not related to CTC, so this wouldn't be the appropriate place to discuss that. cluth 05:00, 7 April 2007 (UTC)

CTC vs. interlocking tower
User:Signalhead tells me the image I added to this article may be to small an area to qualify as CTC, and may belong instead in the article "Interlocking tower". He's unsure because his knowledge is mostly UK rather that U.S., and I'm unsure because I know very little about the topic at hand; I just happen to have taken the photo because I was in the Snoqualmie Depot to photograph its architecture and saw this. Can someone please sort out exactly how this should be characterized, and where it belongs? It would also be greatly appreciated if someone could, if needed, correct the description on Commons.

In any case, nothing in a quick read of this article told me this would not qualify as CTC, so if this does not qualify as a CTC control panel, then a photo here of an actual CTC control panel would be very useful for clarification. - Jmabel | Talk 16:21, 16 September 2007 (UTC)


 * I would not consider this a cTc machine - the picture is of a GRS Model-2 interlocking machine, which pre-dates cTc.  It only controls a single location, not many locations remotely.    This picture should be under "Interlocking Tower" or "Interlocking Machine".  Rwhite502 (talk) 16:21, 22 December 2007 (UTC)

Landlines vs Wireless Links
The article currently says "Recently the costs of CTC has fallen as new technologies such as microwave, satellite and rail based data links have eliminated the need for wire pole lines or fiber optic links." One of the significant costs of running electrical or fiber optic cables in most industries is obtaining property rights for the route where the cable will be run. However, railroads tend to already have those property rights, which should make such wired links potentially cheaper for railroads than for other industries. (And in a lot of cases, if railroads install fiber optic cable, they can use it both for their own communications and can also lease strands of fiber in the same bundle to telecommunications companies, which may in some cases end up getting the telecommunications companies to pay the installation costs of the fiber that the railroad is using for its own communications.) I really think if that text is going to stay there, it needs a link to a source that specifically explains that for a railroad, these wireless technologies are cheaper than burying fiber on the land the railroad already controls. (There may very well be cases where the electric utilities have already installed fiber that gets everywhere the telecommunications companies want to go.) JNW2 (talk) 21:22, 5 April 2008 (UTC)


 * The proof of the pudding is in the eating. Right now when classic signaling or old CTC systems are replaced by new CTC the transmission medium of choice is packet radio links using microwave or UHF.  The common standard is known as ATCS, there's a large Yahoo group dedicated to railfans using their scanners or ham radios to get real-time CTC displays on their laptops.  This technology is spreading all over the place and a company wouldn't be installing this stuff unless had cost savings.  Laying cable over hundreds of miles of route is going to be more costly than a radio tower every 5-10 miles.Sturmovik (talk) 03:46, 19 April 2008 (UTC)

USA bias?
Is this article intended to refer only to US practise? If not, it's very biased. Dick Holman.Archolman 02:23, 8 December 2010 (UTC)


 * Shurely not intended, but things in WP are structured different. In german WP are existing articles on CBTC (mainly for light rail), but also on 'Relaisstellwerk', 'Elektronisches Stellwerk' and 'Digitales Stellwerk'. In ETCS are functional foundations for heavy railways, so traffic control is a higher level to be reached with ERTMS. This article is in 2017 mostly corresponding to "Relaisstellwerk". So it is to be discussed, if structure of articles should be harmonized i.e. common main article like "Stellwerk" and separate specialized articles on technical milestones with regional/national aspects. This is also ergonomic and economic in sense of knowledge transmission.

Saxobav (talk) 22:21, 23 December 2017 (UTC)

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Photo of Promenade Street Tower isn't CTC?
I wouldn't qualify myself as an expert, but looking at this photo, I'm fairly certain that this isn't CTC, but is rather an example of a relay-based interlocking plant. The US&S panel in the photo looks very similar to ones used for CTC, but there's a few reasons to think this installation isn't CTC:
 * None of the levers have code buttons underneath (the buttons that are there are most likely "call-on" buttons)
 * The switch levers in the top row have three indicator lights (US&S CTC panels typically only had two indicators above switch levers)
 * |A contemporary description of the installation describes it as a "relay interlocking"

What does everyone else thing? RAult (talk) 22:03, 25 January 2021 (UTC)
 * Yeah you are correct, that is likely a Style C machine without much 261 track and/or remote interlocking control. The file is used on other pages so I'll just zap it.Sturmovik (talk) 13:43, 26 January 2021 (UTC)