Friday, May 31, 2013

A few Italian signals and an interlocking panel, 2012

After a first posting about Italian points, here is another one with a few Italian signals and an interlocking.

The Serchio valley line from Lucca to Aulla is remote controlled throughout. At Fornaci di Barga, I could take a picture of the local, unmanned interlocking:

Interlocking, Fornaci di Barga, August 2012

Here are some lights going on and off during a train run: A train is coming from Aulla, which is on the left (one can see the connection to the industrial spur shown in my previous posting). Two lower lamps are lighted which are probably indicating route locks; a lamp at the upper right (to Lucca) seems to indicate "line clear", whereas the dark lamp from Aulla means "line occupied":

Interlocking, Fornaci di Barga, August 2012

A short time later, the train is coming into the station. The lamp "from Aulla" is now on ("line clear"), whereas one of the lower lamps is extinguished ("route unlocked"):

Interlocking, Fornaci di Barga, August 2012

The train arrives at the platform:

ALn663 1144 as train R6969, Fornaci di Barga, August 2012

After the train has departed, both lower lamps are off (both routes unlocked ...), and the lamp "to Lucca" is now dark, as the line is now occupied, I'd say:

Interlocking, Fornaci di Barga, August 2012

Behind the interlocking, there is this nice triple clock. All of them are out of order, and I do not understand why three were needed in the first place:

Clocks, Fornaci di Barga, August 2012

On a few trips in the vicinity of Lucca, I took some photos of signals. Italian signalling is not that hard to understand after recognizing that (a) a red light over non-red lights means "slow"; and "moves down" the other lights by one signal head; and that (b) "slow" signals originally did not show the expected speed at the stop signal, but only at the previous distant signal; however, today, one or two white bars are used to indicate the expected speed also at the stop signal. Some explanations can be found here and here.

Italian light signals are "searchlight signals", i.e., they show different colours through one lens. In earlier times, a small mechanical device moved coloured shades into the light path. Today, semi-transparent mirrors are used, or alternatively LEDs. The first two methods are shown on this web page.

The following picture shows a starting signal at Lucca for the line to Aulla. The number "1" is a route indicator ("first" route, counted from the left). The triangle below another signal means "green means slow with 30 kph":

Starting signals towards Aulla and Florence, Lucca, August 2012

And here is the train:

ALn663 1147 as R6962, Lucca, August 2012

By the way, the interlocking of Lucca and signals in Aulla are shown on this page at signalbox.org.

The following signals are at Fornaci di Barga.

Starting signals towards Lucca, Fornaci di Barga, August 2012

At the opposite end, the starting signals are mounted on this signal bridge:

Starting signals towards Aulla, Fornaci di Barga, August 2012

Here is the rightmost starting signal. Apparently, LEDs are used in the signal head. However, I do not know what the black intercepting box contains ...

Loop starting signal, Fornaci di Barga, August 2012

Here is the same signal, with the "30 kph triangle":

Loop starting signal, Fornaci di Barga, August 2012

The last bay but one at Lucca has this signal. Below it, one can recognize the route indicator for the lines to Pisa (1) and Viareggio (2):

Starting signal, Lucca, August 2012

Near Florence, I caught this signal: Slow entry (upper red), maximum speed at next signal (lower green):

Signal, Firenze Rifredi, August 2012

And here is the most famous Italian signal, the "Christmas tree": Red and yellow and green at the same time!
  • Upper red = slow (actually "diverging route"); in this case, there is a bar below the signal, which indicates the allowed speed at this signal: One bar means 60 kph.
  • Yellow and green = slow with 30 kph at next signal.
"2" is the route indicator ("second track, counted from left"), "EST" is "esterno" ("outermost", i.e. home signal), but I do not know what "COD" means (cab signalling in place??):

"Albero di Natale" (Christmas tree), Pisa San Rossore, August 2012

2 comments:

  1. The lozenge with a solid black contour and COD inside means that from there on pulse-code cab signalling is available. The corresponding distant board has its contour dashed. The ending point of pulse-code cab signalling is marked by two similar boards (dashed contour and then solid contour) with COD crossed out.

    Complex stations may have multiple home and starting signals. Inner signals are marked INT (eventually followed by a number if more than one) whereas outer signals are marked EST. Home signals have yellow boards, starting signals have them white.

    As you correctly write, a red over green aspect means line clear at reduced speed. When departing from (or passing through) a track involving diverging points (e.g. a side track) the signal protecting the points could never show just green but always red over green because of the required permament speed reduction. Therefore the upper head of the signal would be there just to show always red, so it gets replaced by the downward white triangle. In other words, when seeing the downward triangle one must imagine the presence of a topmost head showing red. The triangle may be plain or with a 60 inside. In the first case speed is limited to 30 km/h (equivalent to red over green), in the second case to 60 km/h (i.e. red over green with one white bar below).

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  2. The "tooth" below the sunshade is a leftover of movable screen signals. Although searchlight signals were immune from the most dangerous forms of phantom effect, in some cases it could happen anyway, e.g. green could appear yellow-ish, and that tooth was found to be very effective in preventing it when the sun was very low on the horizon.

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