Why I like rail signaling so much.

[CrazyDiamond]

I guess if policy allows trains to stop and then proceed at restricted speed, then I guess its safe to assume that its policy not to have an empty block between two trains.

[chad thomas]

They can pull up behind eachother at restricted speed. At Cajon pass it is common for westbounds to stack up one behind the other waiting to ascend the greade. Sometimes there are as many as 4-5 trains "stacked up" bumper to bumper so to speak. Here is an example at Martinez spur, this is the 3rd in a lineup of four trains:

[tree68]

With some exceptions, signals are set up to allow for adequate stopping distance "at speed." In the cases cited, where trains are in "stop and proceed at restricted speed" mode, I would assume that it might be possible to have several trains backed up between two signals. The first train in line would likely be facing an absolute signal, such as one at an interlocking or possibly controlling access to the yard.

[CrazyDiamond]

QUOTE: Originally posted by tree68

The first train in line would likely be facing an absolute signal, such as one at an interlocking or possibly controlling access to the yard.

I am assuming this includes the classic "x"and "+" style crossings where track "A" and track "B" cross?

Which brings me a new question. First the scenario: Track "A" is owned by RR "A" and track "B" is owned by RR "B". Their track cross over one another at crossing "AB", and "AB" is guarded with signals. Typically wWho owns the signals at this crossing? Do they each deploy their signals? Do they each use their own signaling equipment / cabinet? ...and then the two have some amount of signaling logic communicated between each others cabinet?

[chad thomas]

The way I understand it the railroad (b) that wants to cross the existing railroad (a) is responsable for building & maintaining the tower / interlocker, or installing the signal equiptment for automatic interlockings. Although I'm sure there are many exceptions and variances. Most interlockings I know of are either in CTC territory or are automatic (first come first serve). We don't have that many towers out west anymore.

[CrazyDiamond]

If I were RR "A" I would want my own signaling equipment there too...for various reasons.

[CrazyDiamond]

Phew...I got lots of catching up to do on this site.

Advanced GPS.....I wonder if it will become a part of RR signaling someday. The future generations of GPS promise to pinpoint a receiver with an accuracy down to an inch or two. With GPS on board, and maybe the trains communicating with some sort of wireless (broadband, or satelite?) system, the whole RR signaling system could see dramatic change in the next 20 years or so....maybe sooner.

All I know is technology companies are producing some very innovative technology, and they have the capability to build in all the fail safe and levels of reliability a customer could ask for with a business case that shows a soild return of investment.

Telecommunications companies around the world are tearing out billions of dollars of equipment and replacing it with Internet Protocol (IP) based equipment, tractor-trailor companies are investing heavily in Information Technology, including satellite, GPS and broadband communications to extract more from their fleet, airlines are starting to buy into auto-pilot technology, highways/roads/briges toll administrations and (can you belive this) various sorts of drive throughs, ticket counters/kiosks, etc, are investing in RFID technology to increase efficiency.

You can't convine me the RR signaling system will not under go some new substantial changes in the near future.

[beaulieu]

CrazyDiamond the Europeans are slowly going to GSM-R for signal transmissions and radio communications in conjunction with ERTMS and ETCS. So, it is a high grade version of cell phone technology. They are in the very early days with the first installation having just gone operational near Leipzig in Germany. All previous installations have been for test purposes.

[chad thomas]

I think GPG will be a key element in future traffic controll but it needs to be more accurate and more RELIABLE first. Then you would have to deal with tunnels and deep canyons in a special way. GPS works by timeing when signals arrive at the unit from at least 3 satellites to triangulate from. When you don't have a good wide view of the sky it doesn't work. I have wondered about how they will handle this, especially in tunnels. And another thing, if the GPS based system has a GPS failure, what kind of backup system would they use?

[CrazyDiamond]

Yes it is interesting. GPS will prove to me like any other technology. 20 years from now, all 'significant issues' will be resolved and it will be used widely, either alone, or in conjuction with something else..... i.e. the Internet.

Interestingly enough, there is going to be a launching of a whole new slew of GPS satellites that not not owned by the USA miltary.