A narrow gauge railway, unlike a standard gauge railway which is part of a large network, is a self-contained affair centred on a small area or perhaps meant to bring one kind of product to an outlet for further transport. On the other hand if there are various industrial products and cattle or agricultural supplies to be carried, your railway is something of a common carrier. In that case the next step is to think about the traffic requirements and the goods stock you need.

I looked at the industries most likely to be found on the West Coast of Scotland, added one or two others and made a list of what kind of traffic they would require and generate, and what kind of goods vehicle would be needed. Apart from coal, fish, livestock, wool and domestic supplies, the railway carries granite from the Glenfinnan branch, mining supplies like timber, tools and machinery to Inverlochan, supplies to and whisky from the distillery at Rae Bridge, and traffic to and from the foundry outside Dunalistair.

An example of traffic requirements for a whisky distillery:

This list is limited to one industry only, but if we extend this to other industries and consider the source and destination of products in the list, traffic flows between industries can be identified. On the CDR there are a number of other industries which depend on each other. The colliery at Inverlochan, the railway repair works at Rae Bridge and the shipyard at Dunalistair all contract their heavy repair work out to the Caledonia Foundry at Dunalistair. This results in traffic flows using open and flat vehicles carrying a variety of products between at least four locations: scrap iron, steel and iron products, defective machinery, and new or repaired machinery.

Transporting only one product on a set route, like slate, coal or gravel, means the traffic flow is fairly regular. Some of the traffic on any layout won’t change very much therefore, but if the random flow of general goods traffic has to be represented (which is much more interesting), the challenge is finding a reason to move a vehicle from A to B.

For a long time in model railway operation, card order systems and computer programs have been used to forward goods vehicles to a new destination, some even naming the commodity to be transported, like barrels of this or bags of that. A drawback of this approach is the amount of work necessary to keep track of every vehicle on the layout. Any time a train is run without shuffling the cards around or without following the computer's forwarding orders, the system becomes inconsistent with the actual situation on the layout, and has to be sorted out.

Many years ago, the late John Allen in California was faced with the same problem. On his huge Gorre & Daphetid Railroad he had to keep track of hundreds of items of goods stock, and with operating sessions attended by several people a simple solution was necessary. He introduced a tagging system, with every boxcar carrying its own routeing indicator on its roof. The principle can be applied to any type of layout, and having read of this approach in an article published in the American magazine Model Railroader, in the mid-1980s I decided to try the same on the C&DR.

The principle of the tagging system is as follows. For every goods vehicle on the C&DR four different destinations have been worked out, which the vehicle is taken to in turn. Thus, a cattle van might start its journey on the quay at Dunalistair and be forwarded empty to the Glenclachan loading bank. There James Maclaren loads it with sheep for the market in Craigcorrie, whence the van proceeds empty to Rae Bridge. Here it is loaded with cattle to be taken to the quay at Dunalistair, where a coaster waits to take them as a deck load to the standard gauge railhead at Mallaig. This way the van has come full circle, having been taken by several timetabled trains to each of four destinations.

The tags or waybills used on C&DR rolling stock consist of small colour coded steel washers attached to a roof ventilator, or to a short piece of wire inserted into a van roof or the surface of a flat wagon. Open wagons are less trouble as the 'waybill' is laid on top of the load or on the floor of an empty wagon. Both sides of the washer are coded, each with two destinations. Each station is represented by painting a sector of the washer in its designated colour. On the C&DR these are as follows:

The principle of the system is shown in the diagram. On each side of the washer, the first destination the van has to be taken to is coded along two-thirds of its circumference. The second destination is coded along the remaining one-third. Once the van has arrived in the second station, the washer is turned over using tweezers, and displays the next two destinations. A refinement of the system for Dunalistair and Rae Bridge is a code number for the siding the vehicle is to be taken to on arrival. With white paint a number of small dots are marked on the part of the washer designating each station:

Running a goods or mixed train now becomes a fairly simple process, provided that one is familiar with the codes on the waybills. Providing a quick reference card at each station helps, but after a few operating sessions it becomes unnecessary as the codes are remembered automatically. When the train enters a station, the markers on each vehicle are checked to see whether it has to be detached and to which siding it has to go. Similarly, a check of the stock already present in the station will show which will need to be taken along and which is waiting for a train into the other direction.

The advantages of the system are obvious. It is inexpensive, it gives the destination of the vehicle directly without reference to card orders, and it results in a nearly random traffic flow with unpredictable train loads. When trains have been run for visitors, the goods stock is parked in the first available siding. During the next operating session it is forwarded to the first destination displayed on the tag. There are however some practical problems.

One practical problem is the trains in the Craigcorrie return loops being difficult to access to change over the destination tags. Craigcorrie (code red) is therefore always represented on a two thirds sector of the tag washer. This means that each vehicle returns from Craigcorrie with a valid destination code (on the last third of the tag washer's circumference) ready to be read.

A second problem is that of a terminal station like Dunalistair. Whilst at any passing station the mean exchange rate of goods stock is 50% for each goods train passing through (two directions from the station being available), at a terminal station this would be 100% with only one direction available. Exchanging half the goods stock with every train can be expected in prototype traffic, but all of it would be a bit unrealistic. Therefore goods stock outward bound from Dunalistair has to be spread between the mixed train and the evening goods. Once I used a special colour mark on the marker tag to indicate the vehicle had to be taken on the mixed train, but now the distinction is made between vacuum-fitted and unfitted stock. This is caused by the goods working regulations I put in force recently.

In addition, a few destinations of one or two fitted vans are marked with a yellow dot to indicate express traffic. These are meant to be included in the first available train going in the right direction. This could represent a van of perishables that must be attached to the first passenger train or railcar. Cattle and fish vans are regarded as express workings at all times without needing the extra marker.

There are several isolated sidings where no run-round is available. The Caledonia Foundry siding at Dunalistair is situated at the rear of the layout and therefore cannot be shunted normally as it cannot be reached by hand to uncouple rolling stock. In practice, the Foundry’s own engine is locked up in the siding with a few wagons. Whenever goods vehicles with the foundry code on their tags arrive at Dunalistair, the shunter is activated and exchanges its wagons for the newcomers, returning for further imprisonment in the siding. At Glenclachan, stock destined for Rae Bridge or Dunalistair has to go via Craigcorrie. Similarly, vehicles sent to Inverlochan travel by way of Craigcorrie to be pointed into the right direction on arrival.

Even over 50 goods vehicles the same train make-ups seem to return from time to time. If it becomes boring, I change the washer tags around a bit and new combinations result. When new stock is built, sidings and stations might become congested. The answer is simple: increase the number of Craigcorrie codes on the tags, so more stock is kept out of sight!

Since having introduced vehicle tagging on the C&DR, goods train operation has become much more interesting than passenger traffic. The tags on my stock, though unprototypical, are quite unobtrusive, and the variety in train make-up more than compensates what might be interpreted as gaily coloured lifebuoys on my goods stock.

Train loads vary considerably. Sometimes double heading or banking is necessary, but equally a light engine and brake van can result from the unpredictable traffic flow. When a station becomes overcrowded, the stationmaster has to telegraph his neighbour along the line to relieve him from his burden. Things become really nice when the harbour shunter has to be recalled from ballast train duty at the other end of the line to bank a heavy train up Kinlochalastair Bank.

Angus Macnab, the regular driver of engine 3 'Maid of the Loch', is justly proud of the old lady. He treats her like his baby daughter, and hates having to thrash her uphill. It's bad for the bearings, he says, and she really is no goods engine. Not everyone agrees to that, and only last month on the evening goods he was surprised with ten loads out of Dunalistair, and that with the standby engine away for boiler washing. No one knows exactly what Angus said to the unfortunate goods clerk in his lean-to office behind the goods shed, but rumour has it he didn't show himself for a week...