Can someone identify what this object is between sleepers ?

[0121modeller]

I walked a disused railway tunnel in dudley, came across this item which was pinned in ballast/foundation between concrete sleepers.

I only came across the one.

 

.

The head is mounted on a 1" dia shaft & lifts up/down an inch or so.

The boxy looking item is approx 4" x 4" x 4" .

 

Thanks in advance for replies.

[Trog]

Its a marker for surveying. You set up a theodolite etc. over the centre of the pin through the middle of the block. Then you know you are measuring from the same place as last time, and can compare the results to check for movement or extend the original survey.

[Bomag]

A similar concrete monument was used for setting out curves. The are unfortunately incomatible with high speed balast cleaners which is why in the late 80's and early 90's you regularly saw them in the cess. Given that it is a tunnel would not be subject to the high speed cleaners then it it has survived.

[PrestburyJack]

I've seen similar discs with a pin in the middle in roads - are they the same?

[buffalo]

I've seen similar discs with a pin in the middle in roads - are they the same?

Yes, almost certainly. You may also encounter an older form that looks rather like a six inch nail has been banged into the ground through a plain 2" diameter washer.

 

Nick

[0121modeller]

Thanks for all replies, very helpfull.

 

I can now imagine what it was used for & its reason for being there,

The location of the item in my OP question was on the south-bound track, half way into the dis-used Dudley railway tunnel .

 

I also noticed the level of ballast for rail/sleeper height of north-bound track was slightly lower, not by much, only approximately 6 inches.

The tunnel is also on a slight curvature, so the item in my OP would've had something to do with both those factors I'm now assuming.

 

AFAIK, the tunnel & its route from Bescot to Brierley hill has been out of use for approximately 20 years , so are those devices still used on current rail lines ?

 

Thanks again,

Dave.

[Edwin_m]

Probably someone would come in from time to time with surveying equipment to check for signs of movement that might be a warning of possible collapse. This route has long-term plans for reopening, but even if it hadn't then the owner would need to monitor it, as a collapse could lead to a crater opening up on the surface. Dudley has a lot of old mineworkings, some probably unrecorded, increasing the risk of collapse. There was a truly horrifying incident in the fifties near Manchester when a house and its occupants vanished down a shaft that was dug when the tunnel was built but then covered over and forgotten about.

 

Not quite the same thing but I've seen automatic theodolite type things in the London Underground - there was one on the eastbound Jubilee at London Bridge a year or two back when I was last a regular user, and another one on the Northern at Kings Cross I think. Each one was mounted well above head height and would continuously be panning and tilting, presumably checking the exact position of a set of targets fixed elsewhere in the tunnel and raising the alarm if any of them moved. At both places there was and still is a lot of work going on at surface level, which could have affected the tunnels.

[Trog]

A similar concrete monument was used for setting out curves. The are unfortunately incomatible with high speed balast cleaners which is why in the late 80's and early 90's you regularly saw them in the cess. Given that it is a tunnel would not be subject to the high speed cleaners then it it has survived.

 

 

It looks nothing like a Hallade monument, and they were generally placed in the 6' not the 4'.

[Bomag]

It looks nothing like a Hallade monument, and they were generally placed in the 6' not the 4'.

 

I did not say it looked the same, being in concrete is a bit of a big clue. The location depended on the railway - we has several in the 4 foot on single track sections.