Chaining the Railroad

Model Railroader General Discussion (Model Railroader)
1

Railroads, like highways use mileposts to measure distances. Subways on the other hand require a more precise measurement because trains are shorter, more frequent, and signals and other wayside structures are closer together. A surveyors chain is 1000’ long. Since selective compression is required on a model railroad, I am using a chain that is 500’ long, or 5.74 feet using a Stanley tape measure.

I made a train 5.74 feet long to use as my measuring stick and dragged this around the railroad making my measurements.

Line A is measured from the south end of the Chambers street station in a northerly direction.

At marker 23 Line B branches off of it, while Line A continues to marker 45 at the north end of the 242nd Street station which is the end of the line.

Line B is measured from marker A23 located at the south end of the Smith 9th Street station as it loops through the hidden tracks and back to the south end of Chambers Street at marker B14.

Line C is measured southbound from the south end of the Chambers Street Station (marker A0) and goes around the loop at the South Ferry Station returning to Chambers Street at marker C9.

From Marker A 0 to marker A 23 is a distance of 11500 scale feet, or just over 2 scale miles.

From Marker A 32 to marker A 45 is a distance of 11000 scale feet or just under 2 scale miles.

From Marker B 0 to marker B 14 is a distance of 7000 scale feet of over one mile.

From Marker C 0 to marker C 9 is a distance of 4500 scale feet or just under one mile.

From Marker A 0 to Marker A 23 the railroad runs on a four track main line.

From Marker A 23 to Marker A 45 and from Marker B 0 to Marker B 14 the railroad runs on a two track main line.

From Marker C 0 to Marker C 9 the track is measured as if it were a single track line.

A train running from 242nd Street to South Ferry then covers about 25000 scale feet, or about 4.5 mil

3

This gives me a thought… I’ve been struggling with how to mark the “miles” on my layout, and this might provide just the trick.

Considering that our distances are the most substantially compressed dimension, using typical train length in lieu of scale miles could do the trick!

So, when a prototypical train can easily stretch out to a mile in length, it makes sense to take my typical train length of about 25 to 30 cars in N scale translates to about 1,000 feet, or 75" actual. So I can compress my “mile” to 1,000 scale feet, and set my mileposts accordingly… This will help me determine where to put signals, whistle posts, and all manner of scenic and operational elements…

Thanks for spurring this thought process, Lion.

Lee

4

Thanks, I knew there was more to a chain than what I was getting. And I do know that my prototype line, the NYCT uses it’s own chain length for measuring the ROW, but I have been unable to look it up on the sites where once I found it.

GRRRR

5

Actually a chain is 100 ft long.

6

I take it that a locating engineer would not use a surveyor’s 66 foot chain but a Gunter chain of 100’. So I have understood for some time, but perhaps I am wrong.

Crandell

7

OK, The LION stands corrected. NYCT uses a 100’ chain, so it looks like I will revise my chain accordingly. Which is to say that I will multiply each chain station number by 5 since I used a 500’ chain, but I will not bother to plot the in between numbers, unless a signal or a switch requires a different number.

I have printed the numbers on self-adhesive paper which I will wrap around a pin to give me a “Mile-post” or rather a 'Chaining-station" in NYCT parlance. In the Tunnels I can simply paste the number on the wall, ala NYCT.

ROAR

8

Gunter’s Chain

Gunter divided the chain into 100 links, marked off into groups of 10 by brass rings which simplified intermediate measurement. On the face of it, the dimensions make no sense: Each link is 7.92 inches long; 10 links make slightly less than 6 feet 8 inches and a full length of 66 feet. In fact, he had made a brilliant synthesis of two incompatible systems, the traditional English land measurements, based on the number 4, and the newly introduced system of decimals based on the number 10.

9

Woops, not Gunters…my mistake, it was 66 feet. I meant the Ramsden Chain…100 feet.

Crandell

10

American surveyors sometimes used a longer chain of 100 feet (30.48 m), known as the engineer’s chain or Ramsden’s chain.[4] The term chain in this case usually refers to the measuring instrument rather than a unit of length; the distances measured with such an instrument are normally measured in feet (and usually decimal fractions of a foot, not inches).

11

It should also be noted that nearly all engineering and surveying measurements are based on the U.S. SURVEY FOOT as the unit of measure.

In 1959 the INTERNATIONAL FOOT was adopted by the scientific and technical agencies of the UK and USA. This unit of measure differs from the U.S. SURVEY FOOT by about two parts per million. Since the results of many important surveys dating back to as early as the late 18th century are still in use, adoption of the INTERNATIONAL FOOT would introduce inconsistancies were it adopted for engineering and surveying purposes.

12

Interesting idea… When I designed the current layout, I used a string of 12 x 40ft box cars as a standard length mesure.

Furlong… chain… count yourselves lucky in USA and ROC, here in Quebec, original surveying was done under French rule using “arpents” and “perche”, then they converted the measures in imperial units after 1763 and finally, converted again to metric system in the 60’s… I work in an architecture firm and metric drawing are just a joke among us. It doesn’t make sense to use a unit not even use to make buidling supplies… On the other hand, when you convert strange measures on old buildings into french feet, you get round numbers. I always wondered why traditionnal window were 39 inches large until I found out it was exactly 36 french inches.

The straighedge we use to align track on the layout is a wood ruler made in the 1960’s by the Canadian Metric Board, which became our standard distance between tracks.

Matt

13

LION,

I recently signalled an O-scale NY subway layout for a friend. As part of the process, we were going to put the chain numbers below the signal heads, according to a pamphlet he had about the city subways.

We got away from that while getting the signals to work, etc., but now we may have to go back to it.

When I started the project, I was only marginally interested in subways, but now he’s got me building traction models and thinking of how I can get some trolleys on my layout.

Don’t think there’s space this time, but there’s usually a next time … [:)]

Eric

14

Yup, most of the track and signal numbers are on the signals. But my signals are not in yet, so I will paste the chain numbers on the walls or as signs on a straight pin. As I install signals I’ll be able to measure up from the nearest pin and get an accurate number for the signal. On home signals, the ones with two heads on them, the top signal is the block signal and would have the Track and Chain number on it, the lower signal is the interlocking signal, and its number refers to the lever number on the interlocking machine. So if a motorman had to call in an incorrect lineup, he could simply tell the operator the offending lever number to get the correct lineup.