Working out new mileages for older routes?

[zwk500]

One would hope that the shareholders asked the directors at the next AGM how many extra tickets re-mileaging sold; and how much extra freight revenue it brought in!

mods note - split from this thread:

How Did They Count Bridges

This might sound a simple question, but when is a bridge counted as a bridge? Looking at the old OS maps from 1910 I have been trying to count the number of bridges along my old branch line. Now I know certain bridge numbers. Take one of them (bridge No 17), as I go along the route there are...

www.railforums.co.uk

Of course remileaging can bring other value than just extra revenue by allowing clerical work to be completed more quickly or more accurately.

 

[edwin_m]

Of course remileaging can bring other value than just extra revenue by allowing clerical work to be completed more quickly or more accurately.

Once you've got over the vast amount of clerical work needed to change all sorts of records and drawings, and due to the confusion if they find later that they missed some. There are good reasons why re-mileings are very rare and usually cover short sections only.

 

[zwk500]

Once you've got over the vast amount of clerical work needed to change all sorts of records and drawings, and due to the confusion if they find later that they missed some. There are good reasons why re-mileings are very rare and usually cover short sections only.

Oh indeed. Especially in paper days, although computers now make changes of mileage much less problematic in themselves.

 

[edwin_m]

Oh indeed. Especially in paper days, although computers now make changes of mileage much less problematic in themselves.

But there are probably still millions of drawings that are only on paper, or only scans rather than CAD files that can be changed easily. I presume as mileages are in the Sectional Appendix that changes would have to be briefed to drivers (but not structure numbers).

 

[zwk500]

But there are probably still millions of drawings that are only on paper, or only scans rather than CAD files that can be changed easily. I presume as mileages are in the Sectional Appendix that changes would have to be briefed to drivers (but not structure numbers).

Oh, not sure if there are quite millions but yes, almost all the drawings are scans not CAD files. Even modern documents, as they need to hand-signed to authorise. And yes, Mileages would need to be changed in official documentation so it's a lot of route learning. It's why things like short and long miles exist (these are really the only thing's I'd consider worth resurveying, as there's often no warning that a certain mile is only 74 chains or whatever).

 

[D6130]

Oh, not sure if there are quite millions but yes, almost all the drawings are scans not CAD files. Even modern documents, as they need to hand-signed to authorise. And yes, Mileages would need to be changed in official documentation so it's a lot of route learning. It's why things like short and long miles exist (these are really the only thing's I'd consider worth resurveying, as there's often no warning that a certain mile is only 74 chains or whatever).

....and then there is the issue - particularly relevant to the ex-Midland main line - of sections of lne which have subsequently been closed. So, for example, the highest Midland milepost (307, close to Petteril Bridge Junction near Carlisle) is measured via the now-closed Wath Road Junction-Goose Hill Junction via Royston route.

 

[zwk500]

....and then there is the issue - particularly relevant to the ex-Midland main line - of sections of lne which have subsequently been closed. So, for example, the highest Midland milepost (307, close to Petteril Bridge Junction near Carlisle) is measured via the now-closed Wath Road Junction-Goose Hill Junction via Royston route.

Tbh that's not so much of a problem. As long as you have mileages for the existing routes, and where they change, you can work out the distances travelled. The issue is much more if something claims to be a mile but is actually 75 chains, because that's 110 yards of railway that doesn't exist, which when you have trains travelling over it tens of times a day, quickly adds up.
It's especially relevant now that we're using 15-second timing intervals and computer modelling down to 1m accuracy, as the tolerances tighten these little foibles show up whereas when timetables were planned by some chaps around a table-sized graph with fingers in the air it wasn't so vital.