Cross-haulage of empty intermodal wagons

When I worked at the Central Wagon Authority at BRBHQ our remit was to minimise the "fresh air traffic" by optimising the utilisation of common-user wagons through a system of movement instructions and control orders which were intended to eliminate the wasteful cross-haulage of empties.

I noticed that yesterday's 4M61 12:54 Southampton Maritime to Trafford Park Freightliner was half-loaded, with boxes occupying the front half of the train but the rear half completely empty. Southbound intermodal trains heading to Southampton also often include empty wagons. It occurs to me that there is scope to reduce the amount of wasteful cross-haulage of empty wagons, thereby saving expensive fuel and marginally speeding-up the trains after signal checks. Perhaps the manager at Southampton could liaise with their colleague in Manchester and agree how many empties should be detached based on projected loadings for the return working 4O22 at 00:45. Freightliner has a nice orange 08 shunter at Maritime for this very purpose. The surplus empties could be placed in a spare siding ready to be attached if required to the next day's 4M61.

Now I know that the "Liner Train Concept" was for fixed-formation trains with no intermediate remarshalling but this was later diluted by portion-working through the Basford Hall hub. I believe there is scope for similar flexibility in the management of empty wagons.

I think there would be limited appetite to perform additional shunts and stable wagons at somewhere like Southampton Maritime, where space is at a premium. Ad hoc attaching / detaching of wagons would probably be perceived as an unnecessary performance risk, with the potential to cause terminal congestion and slow down operations. There's also a complication where if container bookings are being handled by a 3rd party (such as a contract train for a shipping line or road haulier) the cut-off for container bookings on the return working may be after the outward service has departed, with the number of spaces available on each train forming part of the contract with the rail haulier.

One thing that can happen occasionally is that the end customer for an intermodal train cancels an entire out-and-back working due to insufficient bookings. Also one way of minimising empty spaces is to have empty non-urgent "filler" boxes on hand at inland terminals which can be moved to the ports as and when space on trains permits. Also, in some cases empty spaces on a container train are the result of things like crane failures, late running that reduces terminal time, or other last-minute variables.

I was comparing the number of Southampton Freightliner departures in the 1988 Freight Only Vol 2 book (Rhodes & Shannon) with today. In a table for Eastleigh dated January 1988 there are 7 trains from Southampton on a typical weekday, with 2 of those originating at Millbrook. The current situation (based on a snapshot from Tuesday this week) sees 12 daily departures from Maritime, which will also be significantly longer trains compared to 1988 (I think they typically have to be split across 2 sidings for loading).

Southampton Maritime in 2017 (with a link in the caption to a 1995 view for comparison).
https://www.flickr.com/photos/nicjoynson/38656729185/ (Photo: Nic Joynson)

While there may be limited scope or desire to alter the composition of sets on container trains in line with day-to-day fluctuations in demand, it's fair to say that the modern freight railway is sometimes overly reluctant to detach wagons from block trains even where this would make sense. For example, it's not unusual for aggregate services to return with some loaded wagons for various reasons. In some cases this makes sense, such as where the terminal is served by other trains and there isn't space to leave the wagons, or where the set's next working will take it to a different terminal where the wagons can be offloaded. The basic layout of many terminals (which can make shunting more difficult) combined with the bare minimum of siding space also doesn't encourage leaving wagons behind unless they are seriously defective. But the result is that in some cases wagons will return loaded to their origin before being sent back to the same terminal, meaning they do three loaded journeys instead of one. Half a dozen wagons doing this could weigh 600 tons, so the additional fuel usage is not inconsiderable.

I think the overall preference is usually for simplicity of operations, fixed sets, block trains, minimising shunting and avoiding potential causes of late starts, even when this seems to go against common sense or potentially isn't the most efficient way of doing things. I think the complexity of BR wagonload operations would cause some heart attacks in the present day and age!

There is also the possibility of the train being a contract train where the haulier gets paid the same whether there is one container or 60.

The uncertainties associated with maritime shipping may mean that a working that was expected to need fewer than the maximum number of wagons may turn out to need them after all, as a container ship may arrive later than expected and its cargo loaded onto a later train than had been anticipated.

I saw the same with "merry go round" operations at powers tations, with wagons arriving at the power station empty - presumably because of a failure of the loading equipment at the colliery, or because loading had to be cut short to keep to the trains's or mione's schedule - or leaving the power station still full if the unloading equipment failed (occasionally a wagon's hopper doors would fail to open). This always led to a misreading at the weighbridges, as the "full" bridge was calibrated between, if I recall, 30 and 60 tons, and the "empty" bridge between zero and thirty. (An empty wagon weighed about 12 tons and a full one 45)

What happens when your shortened train arrives at its destination, goes to its next but doesn’t have enough wagons for its load there? You have to take into account containers that have had delayed customs clearance and get released ad hoc. When you want to move your uncoupled and left behind wagons, you can’t necessarily just tag them onto the next available service. That may make it too long, offer insufficient brake force to run at 75mph, arrive too late to be of use etc. Empty wagons in a consist will make virtually no difference to timings or fuel consumption in the grand scheme of it.