Colin Hussey has just posted more information on his Essence blog following on from his comments I published in my last post. I advise you to have a read and study the photos as it is very interesting and shows the complications the railways had to deal with when determining the train load for a section. I particularly like the additional information related to steam passenger and goods locomotives and their respective minimum hauling speeds and the effect that this had on the train load along with ruling grade and any sharp and/or reverse curves encountered in a section.
Colin is to be congratulated for his desire to impart his NSWGR knowledge gained during is working life as a driver and presumably fireman.
Also of interest is a comment on my last post from Bob Stack of South Coast Rail which I post here:
The 10% reduction in load does exist today but is applicable to diesels only.
It is brought about when different locos have various balancing speeds on the
ruling grades making certain locos try and do more work. Their maximum tractive
effort can be at different speeds.
The Train Operating Conditions Manual (which I use to maintain) sets out these
conditions on Pages 45 to 49 (Locomotive Operations) in the following link:
Look in TS TOC 1.
Certain combinations work successfully together and these are set out in the
So in fact the real world is similar to our models in that certain model locos
won't run with others straight out of the box.
A lot of other interesting stuff in the manual as well.
A quick look at page 45 2.11 Mixing Locomotive Types and Table 3 shows which diesel locomotives can be mixed to retain a full train load capacity and which when mixed together must have the train load reduced by 10%.
It would be possible to build this information into my Train Load Calculator spreadsheet with appropriate formulae for the 10% reduction but it would start to make it not so easy to change to suit other State railways, etc. By all means, do download the spreadsheet and modify to suit your own railway or era.
A couple of interesting sections of the Train Operating Conditions Manual that I found are:
Page 56, 3.3 Holding a Stationary Train on a Grade - This will have an impact on any timetable you are using, Cox's Gap loop for instance is on a 1 in 80 grade.
Page 58, 3.7 Track Speed Signs, Table 11 - These would be useful for the modern image modeller
The steam era modeller may not get much from this manual but it can still be interesting to flick through it.