Zero Milepost question

[Hatfield Shed]

I recall reading in a description of railroad construction in the USA, that the radii were defined by the offset (in feet) from a standard length measurement - which distance I cannot now remember. So, what offset unit and chainage distance were standard in the UK is the next question.

[kudu]

Where is / was the Zero post at Kings Cross?

I suspect it was something that was thought up by the same non-railway minded brainbox who also thought up a Platform Zero at various stations??.

FINSBURY PARK [5] formerly Micky

J K Rowling missed a trick with Platform 9.75. She should have chosen an imaginary number.

Kudu

[Bryan]

I recall reading in a description of railroad construction in the USA, that the radii were defined by the offset (in feet) from a standard length measurement - which distance I cannot now remember. So, what offset unit and chainage distance were standard in the UK is the next question.

Usual measurement would be:-
Miles, Chains and Links.
With 80 Chain per Mile
100 links per Chain.
Chain is 22 yards

Later surveys would be refined to Miles, Chains and Yards with parts thereof.

Offset measurements would be in Yards, Feet and Inches or part thereof.
Generally with the dimension being referenced from the running edge of the nearest rail.

[1H was 2E]

Where is / was the Zero post at Kings Cross?

I suspect it was something that was thought up by the same non-railway minded brainbox who also thought up a Platform Zero at various stations??.

FINSBURY PARK [5] formerly Micky

J K Rowling missed a trick with Platform 9.75. She should have chosen an imaginary number.

Kudu

Kudu, you must have been taught REAL maths. I wonder if today's A grade 'students' ever get to encounter the square root of -1? (I've even been told that Physics is now all about climate change and doesn't even mention 7 ton railway trucks being shunted into stationary ones weighing 9 tons - the reason I always liked that subject)
And Micky; I agree platform zero doesn't make sense; but why DID some ancient cleric start AD at 1 not 0?
Sorry for the flippancy - I'm just putting my coat on....

[65447]

I recall reading in a description of railroad construction in the USA, that the radii were defined by the offset (in feet) from a standard length measurement - which distance I cannot now remember. So, what offset unit and chainage distance were standard in the UK is the next question.

In geometry, the straight line across a circle but not passing through the centre is a chord, and the offset from the midpoint of a chord to the circumference is a versine. This only holds true for circular arcs and not for curves beginning or ending with a transition between straight and radius. The Hallade Track Recorder uses this method: http://en.wikipedia.org/wiki/Hallade_method

Usual measurement would be:-
Miles, Chains and Links.
With 80 Chain per Mile
100 links per Chain.
Chain is 22 yards

Later surveys would be refined to Miles, Chains and Yards with parts thereof.

Offset measurements would be in Yards, Feet and Inches or part thereof.
Generally with the dimension being referenced from the running edge of the nearest rail.

There's a slight confusion in the tools of measurement stated above - there were two types of chain used, that with 100 links each 1 foot long was an Engineer's chain, the other having 66 links was a Surveyor's chain - the Surveyor used that one for measuring Land in chains.

[Bryan]

The railway surveyor used the 100 link chain.

[Hatfield Shed]

That's prompted the memory: 100 feet, perpendicular offset in feet. And a one foot offset gave a 1 degree curve. (North American practise.) The famed 'Forneys' could negotiate something around a 64 degree curve, necessary on the urban elevated railways, which I think corresponds to about a 30 yard radius.

[65447]

The railway surveyor used the 100 link chain.

The Engineer/Engineering surveyor used the 100ft/100 links chain, the Land surveyor used the 22yds/66feet/66 links chain - I was one of the former at the CCE's KX.

[65447]

And Micky; I agree platform zero doesn't make sense; but why DID some ancient cleric start AD at 1 not 0?
Sorry for the flippancy - I'm just putting my coat on....

Because Zero is a point not a measurement. Year 1 starts after midnight on the very first day - following the zero hour, minute and second - and ends 365(ish) days later on it's 1st anniversary. Hence all the fuss about year 2000 - or should it really have been 1999-2000?
The year before your nth birthday is your nth year, the year after is your n+1th year.

[Bryan]

The railway surveyor used the 100 link chain.

The Engineer/Engineering surveyor used the 100ft/100 links chain, the Land surveyor used the 22yds/66feet/66 links chain - I was one of the former at the CCE's KX.

The 1915 Line diagram for the Rillington - Whitby line clearly shows the detail for Mileage, Chainage etc
First entry that I have to hand reads Pickering DP 6 Mile 49.83 chain or 6 Mile 1096yds
This indicating that the 100 link chain at 22yds is in use at least on NER lines.
This works out around 7" 3/16 per link.
There are Line diagram books full of these examples.

However that is all besides the point.

I assume that no one on here knows where the Zero point was? Other than its theoretical position.

[1H was 2E]

It's worth having a look at the thread BRIDGE NUMBERING;Andy Rush and others raised some relevant points about mileposts. Amongst these was the existence at King's Cross of a NERzero milepost; presumably, mileposts on that company's section of the East Coast carried on from the highest GNR one.
Andy also mentioned legislation in the late Victorian period which resulted in bridge numbering, the ability to display "Trespass" and "Shut and fasten Gate signs" with a penalty for failure to conform; and also re-calculation of mileages.
I believe that one piece of this legislation was to ensure that passengers and goods consignee/ors could check that the fares and rates they were being charged (all of which were based on a rate per mile) were being raised correctly and that mileposts had therefore to be visible from a train. The posts showing miles and quarters seem to support this argument in that they usually display the mileage in each direction at 45degrees.
It also raises the interesting question of what happens when a railway company can (by legislation) make a higher charge over a section of line where the infrastructure costs are high. Because the mechanism for calculating rates and fares was based solely on mileage, I seem to recall there were cases when the chargeable mileage was greater than the distance (and perhaps the Forth Bridge was an example), so presumably in such a case the mileposts would not represent the distance - - but I'm not sure.
Of course, it's a shame that, in all the "Railway Histories" that C. Hamilton Ellis OS Nock and others churned out, no space could ever be found for reference to any of this. Obviously, how fast some loco could go downhill (probably using calculations based on data each with an accuracy of plus or minus about 10 percent) is the only thing that constitutes Railway History, so we'll probably never get to the bottom of it.

[Bill Bedford]

but why DID some ancient cleric start AD at 1 not 0?

Simple -- zero wasn't invented, in the west, until a thousand years after they started counting years Anno Domini.

Still it was really clever of those Romans to count their years backwards........

[Hatfield Shed]

Ho ho ho. As I suspect Bill well knows, anyone involved in serious historical research from the early dark ages and further past can tell how difficult it is to reconcile the many calendar systems then in use to create a truly reliable timeline. Makes railway research a positive holiday by comparison...

[9001 St Paddy]

A Milepost 0 seems a bit daft and "non-british railways" to be honest.


FINSBURY PARK [5] formerly Micky and also tons of Hatfield No3 posts and a onetime 'tele lad' at Welwyn Garden City box.

[StevieG]

In reference to the OP, FWIW I noted the other day that there is one of the triangular-topped concrete 1/4-mile posts at Kings Cross, beside the old Down Slow [ No.1 Slow (a.k.a. 'D' Route) these last 38 years] outside the site of the former latter-day 'elephant house' shed of 'Passenger Loco', within a few feet of being opposite the centre of KX power signal box, and I seem to recall that the modern day Sectional Appendix quotes the southern portals of Gasworks Tunnel as being at 0 M. 22 Chs..