Barmouth Bridge - major refurbishment

[whole diary]

[broadgage]

Had not heard about the white/violet signaling, but was aware that the original GWR^▸ (Great Western Railway) used purple/violet lights in signals for proceed, on some freight lines. This to avoid confusion with green proceed signals on adjacent passenger lines.

Purple or violet light is challenging to produce from oil lit signals since the yellow flame of an oil lamp produces very little blue or violet light.

[Witham Bobby]

What a shame - though I appreciate the cost saving.

It would be curious to know what the law is on that swing bridge. Presumably the Cambrian coast ones - Barmouth and the Dovey crossing whose name escapes me - were both stipulated as there were wharves upstream of the crossing points - though the new line was then ruinous for cargoes by sea. I was surprised to read that the swing span was last operated - for test purposes - around 1987 - surely someone must have taken photos. It's surely not the case that some yachtsman could rock up to the forthcoming fixed span and assert that they have the legal powers to insist that Network Rail swing it to allow passage.

Also, if 'Dovey Plan 'A; for the line to Aberystwith had happened, that would have needed two opening spans in the two bridges that that route would have involved.

(And if 'Dovey plan 'A' for the line up the coast, a bridge across the mouth of the estuary, that would have given the estuary a third, which would have resulted in shipping on the Dovey experiencing the pffaff of three opening bridges, one after the other.)

Also, I need to find a source for my belief that the signalling on the Cambrian Coast line at first wasn't red/amber/green but instead was white and violet in order to avoid confusing the cardigan bay shipping.

Mark

The ability of the bridge to swing will have been one of the conditions in the original Act of Parliament which authorised the railway, I'm sure.  Some kind of legislation would have had to be invoked to remove the obligation from Network Rail

As a railway signalling pedant, I'm going to mention that there are no amber railway signals.  Traffic lights have an amber aspect, but for railway signals it's yellow

Green used to be the colour for caution on signals, with a white light being the clear/proceed aspect in hours of darkness.  It all changed in around the 1920s for fixed signals.  But for handsignals, green was still the aspect indicating slow-down, or caution, and white was the "all right".  I'm not up-to-date as to whether these hand signals remain a thing, with so little by way of shunting moves these days and the advent of radio comms

[Mark A]

As a railway signalling pedant, I'm going to mention that there are no amber railway signals.

Rightly so, and thanks!

I'm starting to wonder if I imagined the white/violet thing...

Mark

[Witham Bobby]

I'm starting to wonder if I imagined the white/violet thing...

Mark

FWIW^▸ (for what it's worth) I don't recall having ever read about violet signal lights

[broadgage]

Here is a reference to the use of purple lights in signals.
https://www.railsigns.uk/sect2page2.html But it was on the old great northern railway and NOT the original GWR^▸ (Great Western Railway) as I erroneously reported above.

Purple and violet are rather similar, and the two terms are often used interchangeably though this is not strictly correct.

[stuving]

This from the Cambrian News contains a video showing the bowstring span replacement process. The mental picture I got from the words in Rail Engineer was of the new girders sitting outside the old ones, similar to Nuneham in 1907. But this shows them sitting inside the existing bridge, though it's hard to believe this "vehicle" is narrow enough for that. It also looks odd that they will trundle the whole thing out from its launch site "near Barmouth" but really on the Fairbourne side, until you realise that there's no flat space for that launch site on the north bank.

[Mark A]

On the Cambrian Coast line's choice of white violet signalling colours ,the mystery deepens. I asked Google's 'Bard' to do some digging and curiously it turned up several references including a couple of books, and the following. I've attempted to search that volume of 'The Engineer' magazine and not turned up with the original reference.

Moral: 'Bard' is probably not ready to do people's homework for them...

Here's Bard's response:

"Sure. The article I was referring to is titled "Signalling on the Cambrian Railways" and it was published in the The Engineer magazine in February 1903. The article discusses the signaling system used on all of the Cambrian Railways, including the Cambrian Coast Railway line.

The article states that the Cambrian Railways used white and violet signals because they were the least likely to be confused with the lights of ships. The article also states that the signals were difficult to see in fog or rain, but that the Cambrian Railways had taken steps to mitigate this problem, such as installing signal lamps with reflectors.

I couldn't find a way to retrieve the full text of the article online, but I did find a summary of the article on the website of the National Railway Museum. The summary states that the article "discusses the use of white and violet signals on the Cambrian Coast Railway line, and the problems that were encountered with these colors."

The summary also states that the article "recommends that the Cambrian Railways should adopt a more standardized signaling system, such as the one used by the Great Western Railway."

I hope this information is helpful!"

Mark

[Witham Bobby]

...

I hope this information is helpful!"[/i]

Mark

That's very interesting indeed.  Thank you.  Every day's a school day

[Mark A]

Trouble is, I don't know if Bard's made it up or indulged wish fulfilment on my behalf. Bard provided four references for this - having checked two of them, including 'The Engineer' magazine, February 1993, they don't contain the information quoted by Google's A.I. The date at which Bard states the practice of using violet / white signalling ceased - 'The 1920s' is also very late in the day - commercial shipping in Cardigan Bay was by then very much a thing of the past, so it's all a bit suspicious. I still won't trust this stuff to do my homework (or be at the controls of a road vehicle, no matter what the colour of the signalling there).

In fact, the next time I leave the house I think I'll dress as a bell bollard.

Mark

[Mark A]

Network Rail's taken the opportunity to give the Cambrian coast line's Dovey bridge a heavy overhaul, resulting in a video that includes brief footage of the (personally chilling) sight of the trackbed on its southern side briefly devoid of rails and sleepers.

This structure when built also opened for shipping but the explainer doesn't delve much into its construction or whether the bridge as it is today has any reminders of *that* function.

Mark

https://www.networkrailmediacentre.co.uk/news/major-refurbishment-of-historic-dovey-junction-viaduct-along-the-cambrian-line-is-complete