Recently I was at a layout with an approximately 1 in 40 ruling grade and I noticed a train with two NSWGR Standard Goods locomotives on a reasonable length train and as I knew the owner/driver I asked if he felt that this was a prototypical load. The answer was that he thought that it was within the tonnage limit for the two locos. Now some time ago I built a train load calculator spreadsheet for my Bylong layout which also has 1 in 40 ruling grades so after taking note of the wagon types and how many of each type were on the train I went home. That night I loaded the Excel spreadsheet with the intention of checking the tonnage for the train but decided that I could improve it and here is the result:
NSWGR Train Load Calculator
The result of my check of the load allowed for these two standard goods locos was that the train if fully loaded was actually about 90 ton over the limit for two standard goods locos on a 1 in 40 ruling grade (590 tons). Now the interesting thing is that the train looked OK, not too long at all. Of course it would depend on whether each wagon was loaded to capacity and I had assumed that each wagon in the train was fully loaded.
When you click on the above link you will be taken to my Google Drive ("in the cloud") location for the spreadsheet from where you will be able to download it. To download just click on the small black arrow under File or click on File and then on Download. The spreadsheet is an XLS version so you don't need Excel 2007 or later to open it.
I have protected the workings of the spreadsheet so that various formulae do not get over written but there is no password so just click on Unprotect Sheet if you wish to change something, but you probably shouldn't have to.
The data entry areas are highlighted in two different greens representing initial set up data and operational (working) data, e.g. how many of which wagon type, which locomotive(s) are to be assigned, etc. Data entered on the Permissible Loads sheet automatically comes in when you enter numbers of wagons. Similarly the motive power drop down list for the train is linked to the locomotive types on the Permissible Load sheet. This brings in the maximum load for the motive power and the equivalent length in 4 wheel wagons.
The spreadsheet can be adjusted for different ruling grades and even locomotive and wagon types, there is no reason why this spreadsheet couldn't be used for another railway system. You will need to determine the ruling grade for your layout and apply this, not the actual ruling grade for the line you maybe modelling. Of course the maximum tonnages for each locomotive type must be obtained from a Working Time Table for an actual section of NSW trackage with a ruling grade that matches your layout ruling grade and it will then need to be entered into the initial set up data cells.
When I set up the Permissable Loads table I generally added the single loads of two steam locomotives together when setting up the spreadsheet which is apparently not correct. I have been told that the maximum load for two steam locomotives was determined by adding the individual loads then reducing the load by about 10%. Note that from the Working Time Table, the loads for two diesels were simply doubled
The tonnage of the train can be adjusted for empty wagons, 25% full wagons, 50% full wagons, 75% full wagons, fully loaded or specific loads per wagon. Examination of a NSWGR Working Time Table will show that often the maximum number of wagons will be stated for both a 100% and a 75% loaded train.
As you can now see, the length of your train is dependent on the percentage load carried for the ruling grade of your layout as well as the number of wagons in the train as this may conflict with the minimum and maximum staging tracks or passing loops.
I have decided that since the NSWGR had information in the Working Time Table for 75% loads then it would seem likely that the target loading for a train was somewhere between 75 and 100% loading. If this is the case then this really helps our portrayal of prototypical operation on our layouts as it restricts the length of our trains to something that our model steam trains can actually haul.
Incidentally, if I used the 75% loaded column for the wagons on the double standard goods train then the load at 565 tons was 25 tons under the allowed maximum load of 590 tons.
I have always used 2 grams per HO foot measured over headstocks as my target for wagon weighting with a little modification for passenger cars. This system allows prototypical length trains to be hauled by our model steam trains sometimes with a little additional weight, but often without. Here is a spreadsheet that can be used to determine the mass of your HO wagons with a +/- 15% range.
HO Wagon Mass Calculator
I should state here that when I set up a train on Bylong which will be banked from the rear it contains wagons that are sufficiently heavy to cause the train locomotive to be unable to haul it up the grades on the layout so that the banking locomotive is truly there to do its job. So, some of these wagons are over the upper limit of the weighting system but for a reason.
As an example of a typical fully loaded train here is a photo of a train headed by a D57 class that just fits into the loop at Bylong yard, not that long is it?
There you are then, a little something to think about and a useful tool if you decide to work to more prototypical length trains.