What are the small numbered signs found along railway lines and what is the red slider used for?

Question

What are the small numbered signs found along railway lines and what is the red slider used for?

Answer 1

Thunderstruck has the most accurate answer.

The small metal plates with red sliders are often noticeable at station platforms where it is most important that the track height is accurate. They show where the top of the rail should be aligned.

There are lots of numbered signs alongside railway lines. here's a few:-

Screwed to upright posts of overhead structures are kilometre (not mile) markers from that route's Datum point,

Those on a diamond shaped blue border are channel numbers for "train to shore" radio,

Warnings of approaching speed limits (yellow triangles) in miles per hour.

Red circle signs indicate speed limits (in mph).

Horizontal or near-horizantal boards indicate gradients.

Answer 2

The numbered boards are mile posts.

In the US, in my neck of the woods, a red "slider," which I would call one half or one side of the letter "V" is called a "flanger board."  There is a piece of snow removal equipment called a "flanger."  Its purpose is to drop a blade in the center of the track, below the top of the rail, to throw out ice, the buildup of which can derail equipment.

The flanger board alerts the engineer that a crossing, or switch (point) lays just ahead.  The crossing, switch, or other device that lays between the tracks cannot be seen under snow pack.  The flanger board reminds you that the obstruction is there, so that the blade of the flanger can be lifted momentarily until clear of the obstruction.

Answer 3

Depends

If it is like a concrete marker and has a large number followed by dashes then they are mile marks from London, if it is a small number which goes up to 80 then it is a chain marker (80 chains to a mile) if it is an oval sign with 54m 37ch for example then it is a distance marker from London

Answer 4

The numbered signs are usually mile markers, so the train crew can radio in their position. Not sure what the red slider is, is it on the signs?

- Born in the USA -

Answer 5

Small numbers if on posts are most likely mile posts found every 1/4 mile.

If on a 'T' shaped post with one are pointing at an angle these are gradient indicators.

If a post with cut out numbers these are speed boards serving the same purpose as those at the roadside. In some areas these have indeed been replaced by a large round sign much the same as along any road.

Red Slider? not a clue.

Answer 6

They are survey markers to check for level, height and any settlement of the track and platforms.

Answer 7

The small numbered signs are most likely mileposts, not sure about red sliders..

Answer 8

Mileposts

Answer 9

If these numbers are small black numbers on a white plate with a red slider on, they relate to the hight of the rail adjacent to a structure such as a platform. They are to give the Track Quality engineers and Tamping machine operators a datum point so that when they are carrying out track repairs they do not alter the geometry of the track to such an extent that the rails are to low or high for the platforms.