Monday, March 13, 2023

Waybills, Part 107: tank cars

I realized in some recent discussions that I had not ever really been specific about some tank car issues, both about waybills and about cargoes. Because these touch on other issues of tank car handling and use, I will summarize those briefly also.

To begin, non-pressure tank cars (ICC types 103 and 104, the overwhelming majority of tank cars in the transition era) were loaded through the dome manway, the dome-top opening. Here is an excellent view of that process. (The photo was taken by John Vachon in November 1942, at the Phillips refinery in Borger, Texas; the image is from the Library of Congress, image no. LC-USW3-011638. I’ve written about Vachon in an earlier post: .) This happens to be a screw-top manway cover.

Such cars had bottom outlet valves (controlled by a long shaft up into the expansion dome, and operated from there). Many photos show this kind of unloading; this one is a Standard Oil photo at Bayway, New Jersey (undated). The nearest tank car, with CYCX reporting marks, belonged to the Conley Tank Car Company. Note also the wheel tread width . . .

On the end of the CYCX tank car, the gallonage is prominently displayed. In the era of riveted tank cars, manufacturing did not produce identical tanks, and each car, when completed, had to be measured and its exact gallonage determined. What did this refer to? It was called the “shell-full” capacity. This was the amount present when the liquid just filled the horizontal part of the tank. It could be easily seen through the manway.

This gallon-capacity is the reason tank cars were not often reweighed; their light weight was not used in calculating cargo weight, as it was in practically all other freight cars. Instead, the convenient loading determination of “shell full” equalled the gallonage on the tank’s end. This gallonage was then the basis for tariff charges.

But the tariff was not actually in gallons, in that if you look in a tariff, the tariff quantities are on the basis of a stated weight per gallon. Obviously you just multiply that factor times the gallons to get weight. As an example, xylene and lubricating oil were both listed as 6.6 pounds per gallon.

This entry is a tariff revision, one of the innumerable and frequent changes to rules in the days of ICC regulation of railroads. It is from this book, tellingly titled “Supplement 72” of Freight Tariff 2-L for the Trans-Continental Freight Bureau ( covering the western region of the United States), dated December 1974. Documents like this, issued every few weeks, filled many feet of shelving in clerk’s offices.

Now let’s look at an actual waybill. An example (generously provided by Andy Laurent from his collection of waybills) is this gasoline waybill. First, note that the waybill is prominently stamped “DANGEROUS.” Second, note that the cargo is “gasoline noibn,” with “noibn” meaning “not otherwise identified by name,” that is, that it may be any grade of gasoline (each grade, including noibn, had a specific tariff rate). Third, note that the gallonage is stated (8156 gallons), but that the tariff charge is from the calculated weight, 53,830 pounds (clearly at 6.6 pounds per gallon). It’s a UTLX car.

Another example that may be of interest is another Andy Laurent waybill, this one for a load of LPG (Liquified Petroleum Gas, usually mostly propane). This waybill too is stamped “DANGEROUS.” Here the car contained 30,701 gallons of LPG, and the weight was 144,295 pounds (4.7 pounds per gallon).

Note that the waybill records that “dangerous” placards were applied; the gasoline waybill above notes the same. This cargo moved in an NATX car. It is important to recognize that a pressurized cargo like this was certainly not loaded to a visual “shell full,” but the liquid was metered as it went into the car.

In summary, tank cars present a number of differences in their cargo handling and waybilling from other freight car types. This of course can be a point of interest and value in model railroad operations — if we choose to take advantage of it.

Tony Thompson


  1. " manufacturing did not produce identical tanks, and each car, when completed, had to be measured and its exact gallonage determined"
    Are there specification to measure the gallonage and do you know where they would be? I think water as a liquid doesn't expand much over it temperature range as some metals.
    Fred Swanson

    1. They did use water (some tanks were stenciled "water gallons"), and my understanding is that they metered the water put into the tank until it was full.
      Tony Thompson