Signal aspects when trains are stopping at through stations

[GordonT]

What are the possible reasons why trains approaching some through stations at which they stop always encounter restrictive signals with no conflicting movements ahead whilst at other stations it's greens all the way unless exceptionally the line is not clear on rare occasions?

 

[king_walnut]

Some signals are approach controlled, usually when taking a diverging route that requires a much lower speed .. we call that the 'signals checking you down'. The red signal will only come off when you're a certain distance away from it.

 

[The Planner]

What are the possible reasons why trains approaching some through stations at which they stop always encounter restrictive signals with no conflicting movements ahead whilst at other stations it's greens all the way unless exceptionally the line is not clear on rare occasions?

Can be as simple as the signaller not setting the route if they are controlled signals. Lots of stations on open track with no junctions/multiple platforms are in auto sections so will be green if nothing is around.

 

[Tomnick]

ARS is often configured not to pull off out of the other end of the station until the platform staff bell it out. It's a minor nuisance at a couple of places where we never get relief or anything anyway, making for a slightly slower approach which is frustrating when you're already late.

Derby PSB had a very successful "green light policy" for several years, allowing trains a quicker approach into the platform. Sadly it was lost when the area was resignalled, co-inciding with an increase in permissible speed ironically. It clearly made enough of a difference to make it worthwhile.

 

[sir_gummerz]

At some stations, the dispatch staff need to "Dial out" the train, by pressing a button that tells the signaler the train is good to leave, its more common at stations with train crew based there, as they want to ensure a train is staffed before giving a routing. Level crossings also play into it, for example at Cheltenham spa, on the up there's a crossing outside the station, and the dispatcher bells the signaller when the train it ready, to reduce the down time of the crossing.

 

[Steve Harris]

At some stations, the dispatch staff need to "Dial out" the train, by pressing a button that tells the signaler the train is good to leave, its more common at stations with train crew based there, as they want to ensure a train is staffed before giving a routing. Level crossings also play into it, for example at Cheltenham spa, on the up there's a crossing outside the station, and the dispatcher bells the signaller when the train it ready, to reduce the down time of the crossing.

Dial out ? I've never heard that one before. The correct term is Train Ready To Start and the button pressed to notify the signaller is labelled as such (T.R.T.S.).

 

[Annetts key]

Dial out ? I've never heard that one before. The correct term is Train Ready To Start and the button pressed to notify the signaller is labelled as such (T.R.T.S.).

Or at some older installations, T.R.S.

There are many possible reasons for signals at stations to be red until the train is ready to leave. Many have already been listed.

Others include:

The signaller wanting to keep their options open in case of problems. Once a route is set and the signal clears, unless there is an emergency, the signaller will want to inform the driver before cancelling the route and putting the signal back to red. Then when the route is cancelled, electrical or computer based interlocking will enforce a time delay (typically 2 to 3 minutes) before the route becomes free, until then all affected points remain locked (as does any manually controlled level crossings). Hence no other routes that need any of those points in a different position can be used until the timer finishes.

A route for an adjacent line may require points to be set to provide flank protection or to provide an overlap for another move (that may not be visible to an observer on the ground at first). Or instead of points, a track circuit or axle counter section may be used instead.

There may be a change of train crew, the signaller will keep the signal red until its confirmed that the train and new crew are ready.

 

[sir_gummerz]

Dial out ? I've never heard that one before. The correct term is Train Ready To Start and the button pressed to notify the signaller is labelled as such (T.R.T.S.).

Among railway staff in the southwest, the act of pressing the TRTS button is referred to as dialing the train out, ie, "he forgot to Dial the train out, causing a delay" I very rarely hear a dispatcher say they TRTSed the train, at least from my experience.

 

[greatkingrat]

Must be local differences. I have never heard the term "dial out" being used, it is always called plunging out here.

 

[Annetts key]

Must be local differences. I have never heard the term "dial out" being used, it is always called plunging out here.

I don't know exactly where or how this term "dial out" came about, but... maybe this is relevant...

On Western, the 1960s train describer (T.D.) system that was installed in the P.S.B.s (including Bristol Panel) used equipment similar to a telephone dial to set-up new train descriptions (head codes). Any train that terminates or originates will need the T.D. changing. At places like Bristol Temple Meads (B.T.M.), this was (and still is) a very common occurrence.

Further, at B.T.M. the right away (R.A.) is only used for non-passenger train movements. All passenger trains are dispatched by the platform staff. Who are the staff that press the T.R.S. buttons (as they used to be known here).

So maybe the two became associated with one another by the signallers and the phrase "dial out" was coined to mean that a train was ready to depart and became popular with the signallers because it was both easier to say and to remember?

Some of the older signallers still used the term "dial in" when referring to entering a new description even though in 1989 the entire T.D. system was renewed in electronic form with computer type keyboards.

 

[InkyScrolls]

Always called 'belling out' where I work (Northern, East Region)

 

[MarkyT]

I don't know exactly where or how this term "dial out" came about, but... maybe this is relevant...

On Western, the 1960s train describer (T.D.) system that was installed in the P.S.B.s (including Bristol Panel) used equipment similar to a telephone dial to set-up new train descriptions (head codes). Any train that terminates or originates will need the T.D. changing. At places like Bristol Temple Meads (B.T.M.), this was (and still is) a very common occurrence.

Further, at B.T.M. the right away (R.A.) is only used for non-passenger train movements. All passenger trains are dispatched by the platform staff. Who are the staff that press the T.R.S. buttons (as they used to be known here).

So maybe the two became associated with one another by the signallers and the phrase "dial out" was coined to mean that a train was ready to depart and became popular with the signallers because it was both easier to say and to remember?

Some of the older signallers still used the term "dial in" when referring to entering a new description even though in 1989 the entire T.D. system was renewed in electronic form with computer type keyboards.

I've seen a few coffee videos on youtube, and experts seem to use the 'dial in' phrase for setting up the various grinding and brewing devices correctly for the particular drink they're trying to produce.

I only saw the rotary electro-mechanical TD displays and their telephone dial data entry method in the flesh at one box, maybe Plymouth, during a brief early 80s training attachment with the panel techs there. Later I recall designing small TD stepping modifications in the drawing office for boxes in S. Wales but I can't remember if they still had the original displays. In many PSBs, they kept the telephone exchange equipment behind the scenes for routing the steps but substituted more modern alphanumeric displays. The Sodeco displays were on their way out, though the phone dial input remained. While the displays were full of character, I think they were a maintenance headache and were fast being replaced, though it wasn't so easy as the displays themselves held the state memory of the train description and a series of ten pulses stepped each character on to the next display when correctly triggered by the track, route and signal indication conditions.

Here's a short Swindon Panel Society clip showing one of the displays in action:

 

[Annetts key]

electro-mechanical TD displays

Yes, these were a nightmare maintenance wise. Because the display was the memory store for the description, if any of the four display barrels failed to operate correctly, you most often got 0Z00 appearing in the next berth/display when the train moved forward. 0Z00 being the "home" position for the display.

The most common problem was a display barrel failing to return to the "home" position due to dirt, contamination or any other poor contact between the fixed contact arm and the brass ring (that you can see in the video) on the display barrel.

At the time, the S&T (Signalling and Telecom) fault team T.O. (Technician Officer) in the P.S.B. where I was a trainee would typically be asked by the signallers multiple times during an eight hour shift to "unstick" the T.D., hence there was always a can of aerosol electronic cleaner (a IPA - Isopropyl alcohol or similar quick drying type, not the lubricant type) to hand in the messroom...

By 1986 an Western Region electronic T.D. system had been developed, known as S.S.T.D. (solid state train describer) and was being installed on the P.S.B.s on Western through 1987 to 1988. There are some photos on "SIGNALLING PHOTOS - The Railway Signalling Photo Archive!" showing both the displays (https://photos.signalling.org/picture?/8334/category/698-2014) and the later Vaughan O.C.U. (operators control unit) complete with keyboard (https://photos.signalling.org/picture?/8292/category/698-2014).

 

[MarkyT]

By 1986 an Western Region electronic T.D. system had been developed, known as S.S.T.D. (solid state train describer) and was being installed on the P.S.B.s on Western through 1987 to 1988. There are some photos on "SIGNALLING PHOTOS - The Railway Signalling Photo Archive!" showing both the displays (https://photos.signalling.org/picture?/8334/category/698-2014) and the later Vaughan O.C.U. (operators control unit) complete with keyboard (https://photos.signalling.org/picture?/8292/category/698-2014).

The head of the WR S&T technical investigations laboratory at Reading designed that system. I think he started developing it as a university project. It had individual cards for each berth with discrete logic on board and no processors. The cards plugged into edge connectors and were interconnected to a custom design at their rear by masses of individual solid core wires terminated on wire-wrap pins. Exeter TD used this tech and while I was training there, installers were wiring the new system, so I had a spell on the wire wrapping tool. A lot of detailed site configuration work compared to later software-based systems.