"Line Blocked" or "Normal"?

[Rescars]

The recent threads elsewhere about the retirement of some of the last remaining GSWR block instruments in use on NR and the history of the BR Penguin instruments raise a question which is more historic than current. Whilst almost all three-position block instruments indicated, as appropriate, "Line Clear" and "Train on Line", there seems to have been less consistency about the third indication. Some instruments showed "Line Blocked" whilst others (like the instruments kindly illustrated by MadMac, Ashley Hill and 4069) showed "Normal". Does anyone know the history or reason for this? Was it merely due to the preferences of the manufacturers or companies' signalling superintendents, or was there some greater significance? Did the BoT have a view? Has the terminology changed over time? All thoughts and observations welcome.

 

[Gloster]

I have always called it Normal and the 1972 and 1981 Regulations for Train Signalling both called it that. The only difference is that in the first it is lower case, while in the second it starts with an upper case N and is in bold.

I wonder if the difference was that Line Blocked could, if you were unaware of the terminology, be interpreted as meaning there was a blockage in section rather than a train. Though I don’t think any signalman would do that.

 

[Ashley Hill]

In the development of block signalling the line was always described as blocked when no trains were either accepted or occupying it. I imagine that is why on the majority of early pre-grouping instruments they all have “line blocked”. I have also seen “line closed” as an alternative.
As to the use of “normal “ I imagine this would have been a company choice, certainly on later GWR instruments.
You may get a professional's opinion at some point.

 

[edwin_m]

If the line is actually blocked aren't they supposed to peg it to "Train on Line"?

 

[Gloster]

If the line is actually blocked aren't they supposed to peg it to "Train on Line"?

Yes: if you have an obstruction or engineering work then the indicator is turned to Train on Line unless, if I remember correctly, you have Single Line Working in operation. However, I was thinking that there is a vague possibility of confusion by someone outside the signalling grades as to the meaning of Line Blocked.

 

[Ashley Hill]

Perhaps this is why “line blocked” was later changed to “Normal” on later instruments to avoid confusion.

 

[Tester]

By way of variation, I have a block instrument which has no labelled third position.

Without power applied, it hangs half 'Line Clear' and half 'Train on Line'.

 

[Pigeon]

If the line is actually blocked aren't they supposed to peg it to "Train on Line"?

Yes: if you have an obstruction or engineering work then the indicator is turned to Train on Line unless, if I remember correctly, you have Single Line Working in operation. However, I was thinking that there is a vague possibility of confusion by someone outside the signalling grades as to the meaning of Line Blocked.

Well I've always found it highly confusing. You turn it to "Line Blocked" when the line is not blocked... this manufactures nasal chickens. "Normal" is perhaps not the best choice of alternative but it's a vast improvement.

 

[edwin_m]

"Normal" is perhaps not the best choice of alternative but it's a vast improvement.

Maybe because most levers in most boxes were returned to the "normal" position (back) when not specifically required to be reversed? Points still have a normal and a reverse setting, although when controlled by something other than levers most of them are just left where they are until a route calls them to the other one.

 

[Ashley Hill]

Well I've always found it highly confusing. You turn it to "Line Blocked" when the line is not blocked

A block section is considered “blocked” until it is unblocked by signaller ahead accepting a train by turning his switch to “line clear”.

 

[edwin_m]

A block section is considered “blocked” until it is unblocked by signaller ahead accepting a train by turning his switch to “line clear”.

But there is obvious potential for confusion if the term "line blocked" could have this meaning but could also mean there is some obstruction that prevents the line being used. It probably didn't happen much when most operating staff had an understanding of Absolute Block, but once is too many and more recently the filling of posts by those who aren't career railwaypeople probably makes it more likely.

 

[Rescars]

Thanks for all responses so far. I have now found instructions for SR Sykes Lock and Block instruments dated 1960. These illustrate the three positions on the block indicator as "Line clear", "Train on line or line blocked" and "Normal (blocked)"! These are separate from the tablet indicators which show "Locked", "Free", "Train on" and "blank" at various stages of the acceptance process. Clearly a system for operating by the fully initiated only!

 

[Ashley Hill]

The trouble is that the w

But there is obvious potential for confusion if the term "line blocked" could have this meaning but could also mean there is some obstruction that prevents the line being used. It probably didn't happen much when most operating staff had an understanding of Absolute Block, but once is too many and more recently the filling of posts by those who aren't career railwaypeople probably makes it more likely.

Indeed, the phrase “block” is used for too many things these days. We take a “line block” to work on the outside of our trains. “Blocked to electric traction “, an example of blocked but not blocked so to speak. It’s overuse waters down the words ultimate use for when your train has derailed and you make an emergency call to say “all lines blocked”.

 

[matchmaker]

The oldest textbook I have on signalling is "Railway Signal Engineering (Mechanical)" by L P Lewis, originally published in 1910. In the section on Absolute Block instruments it is stated "Line Blocked simply means that the line is Closed". I'd suggest that "Normal" is a more modern interpretation of this, as Absolute Block is a normally closed block system.

 

[Gloster]

The oldest textbook I have on signalling is "Railway Signal Engineering (Mechanical)" by L P Lewis, originally published in 1910. In the section on Absolute Block instruments it is stated "Line Blocked simply means that the line is Closed". I'd suggest that "Normal" is a more modern interpretation of this, as Absolute Block is a normally closed block system.

And there you would have another point of confusion. Does ‘Closed’ mean that no train is signalled, that the line is not available for use due to some restriction or just that everyone has gone home?

Absolute Block is a closed block system: that is the basis of it. Any deviation from that is either another system, such as Permissive Block, or a temporary application of emergency rules.

I would say that Normal may have become the standard word for the ‘Nothing happening’ indication on the instrument as, as far as the working of the instruments were concerned, it had no other meaning, but other words could. But then, there is still ‘Normal’ working of the whole set up, as opposed to some emergency or special working, such as Single Line Working.

 

[edwin_m]

Perhaps with hindsight "line obstructed" would have been a better term for the line not being physically able to operate trains. This fits with the use of "obstruction danger" in the list of bell codes.

 

[Ashley Hill]

Here’s an example of a block instrument showing line closed. It’s an L&Y Tyers block. Sadly not one of mine.

Photo GNRA

 

[midland1]

By way of variation, I have a block instrument which has no labelled third position.

Without power applied, it hangs half 'Line Clear' and half 'Train on Line'.

Is that an ex Great Western one? The LNWR used line closed.

 

[Tester]

Is that an ex Great Western one? The LNWR used line closed.

Yes it's a Spagnoletti.

 

[Belperpete]

Very early block instruments only had two positions, often using an indicator looking like a miniature semaphore signal. "Line Clear" (permission for a train to enter section) and "Line Blocked" (you don't have permission). Three position instruments were later introduced to give a distinct indication for train in section, to reduce the likelihood of a signalman forgetting that there is a train in section and pegging to Line Clear. I suspect that the variation in wording is a hangover from this. I am not aware of any two-position instruments still in use.

 

[Gonzoiku]

Here’s an example of a block instrument showing line closed. It’s an L&Y Tyers block. Sadly not one of mine.
View attachment 192661
Photo GNRA

I don't recall what my long-gone L&Y block instrument reported, but I have photos of an LNWR block instrument from 1902, and an almost identical BR(M) instrument from the 1950s which both report Line closed".

GZ

 

[Harpo]

As well as the language around ‘blocked’ there’s also the use of ‘occupied’ to describe a section. That can be an ‘engineers occupation’ as in the railway being in the possession of either the operator or the engineer. Of those, only ‘engineer’s possession’ is commonly used nowadays but engineers are still said to ‘hand back’ possessions or ‘blocks’.