How is this squared with the customer? Presume , over time, they would not get the amount of stone they thought they should have?Are extra trains run to make up for this?
In the opposite- I was informed a couple of years ago of empty wagons running in an otherwise loaded consist because those empties were faulty in some way and could not carry any load. So, a nominal 2200 ton train of say 24 wagons was not actually anything like that, I hope the customer was made aware of this!
There will be a record of the weight of material loaded into each train (often recorded by the train passing over a weighbridge on arrival and departure at the loading siding). For example if a train loads 2000 tons and returns with 200 tons of product, the next day it might load 1800 tons but discharge 2000 tons including the material from the previous day. It will be recorded that 3800 tons were loaded and delivered in total.
Most aggregate services run to a weekly plan and the number of trains ordered can vary from week to week depending on terminal stock levels and demand for material; if a train is cancelled one week there may be scope to run an additional train the following week. There will be conditions in the contracts to deal with issues like short notice cancellations by the rail operator or customer, defective wagons that can't be loaded, or a train that was supposed to run with 24 wagons only having 23 on it, situations where trains can't be fully offloaded due to customer equipment breakdown or late arrival and so on.
On YouTube the "Ashville" channel is very good for showing the operations at a typical aggregate depot (Thorney Mill) and some of the issues involved -
https://www.youtube.com/c/thisisashville/search?query=train
They recently did a full video about offloading trains, titled "How We Offload a Freight Train in 3hrs to Avoid a £20k Fine!"
I think the "fine" they mention is a charge (possibly £1000 per wagon?) that they would have to pay if they return wagons loaded, which then have the wrong product in them (i.e. different size or grade of aggregate) for the next planned working from the loading point to a different customer.
Wagons sometimes return loaded from a terminal when the bays containing a certain type of material are full, but at Little Kimble the issue is more likely to be due to time constraints as mentioned in posts above. With HS2 everything is on a different scale and there are huge volumes being moved compared to a typical aggregate depot serving general construction work.
www.realtimetrains.co.uk
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