Monday, July 25, 2011

A few words on packing houses and produce shipping-3

In my previous post on this topic, I discussed pre-cooling, pre-icing, and related issues for refrigerator car service (see: This time I am going to say a little about car loading for shipment.
   I mentioned in my first post on produce shipping that the containers used for various fruits and vegetables varied in size, but all were optimized to fit into the standard refrigerator car interior, and also be appropriate for the particular kind of produce (see: Here is an illustration of a load of containers as packed into an ice refrigerator (the drawing is from the SP Bulletin, 1928):

Note that in the car center, spacers have been placed both to complete the filling of the load space, and to make it easy for workmen to get into the car for unloading. Air flow for ventilation service is illustrated.
     Depending on the shape and size of containers, the produce would be stacked various ways in the car. It can be noticed in the drawing above that the load does not reach the ceiling, largely to ensure good air flow. The same was done with orange crates, as shown here (it’s a Sunkist photo from my collection):

This image dates from the 1920s and shows the hand truck so often used for loading in early days. Note also the so-called “car strips” in the doorway at right, used to make sure that the load fit firmly into the car interior. The bulging crates are a deliberate feature, to provide some “spring” in the load tightness. Also evident here is the square end shape of the crate.
     A similar but larger crate was used for lettuce. Here is a view from the 1950s of lettuce loading at Salinas (this is a PFE photo from my collection):

The roller trays used to deliver crates to the loading spot are very commonly seen in photos. These crates also have some “spring” to them.
     A leafy vegetable somewhat like lettuce but shipped as upright plants is celery. Here is a later view of celery crates, being loaded by fork lift truck into a later car with load dividers (the image is from southern California, a UP photo provided by Terry Metcalfe):

The crates are taller than they are wide, in keeping with the shape of celery in its shipped form.
     My last loading example is cantaloupes, shipped from the Coit Ranch in Firebaugh, California. Again, the crates are a different shape, and are stacked in the car on edge. The ice bunker wall has a portable fan mounted for air circulation during loading, likely implying that the car has been pre-iced. This photo is from the Railfan and Railroad magazine collection.

     Most of these crates are not widely different from square in the end view. But several other crops used quite different crate shapes. Both tomatoes and pears, being more fragile produce, used a very flat crate, as can be recognized from this pear box label (from the days when the region was called the Santa Clara Valley, not yet Silicon Valley):

     These examples, largely drawn from the PFE book though cropped somewhat differently, should suffice to illustrate that modeling shipping arrangements requires knowing the crate size and shape for the produce you are modeling.
Tony Thompson


  1. Tony,

    From a modeling standpoint I want to bring up the subject of package pre-cooling and top icing. I have recently been reading about the introduction of vacuum cooling to remove field heat from commodities such as lettuce and carrots. Commercial experimentation with this began around 1946 in the Salinas valley for lettuce. This cooling methodology involved placing un-iced, pre-packed lettuce crates in a sealable enclosure and applying a partial vacuum to the container once it was sealed. This technology removed the field heat from the packed lettuce heads prior to packing them into the refrigerator cars. This resulted in less ice usage and better end product life.

    Prior to the widespread adoption of this vacuum pre-cooling technique, it was common practice to add crushed ice to the actual wood packing crates for commodities such as lettuce and carrots to help remove the field heat. At this time it was also common to top ice loads such as lettuce and carrots. All of this was to reduce the field heat damage to the crop.

    For one car load of lettuce there would be 30 pounds of crushed ice in each of the largest lettuce packing crates along with 10,600 pounds of ice in the ice bunkers plus 20,000 pounds of crushed ice on top of and amongst some of the loaded crates. This meant immense ice needs and added labor costs for every load. Some packing sheds would add their own top ice using chutes at trackside where the crate loading was done. To do so they had to have a significant ice source either within the packing shed itself or via conveyor from another building.

    Your 1950's lettuce loading in Salinas photo shows the folded crushed ice chutes above the conveyor in the photo. You also mentioned the bulging containers on the conveyor. One of the reasons for the bulging containers was typically the added crushed ice added to each container to help cool it.

    Not all sheds did their own top icing, so separate top icing service facilities were typically available in the larger packing locations. I know at Watsonville Junction there was a 5 car spot facility on the north side of the yard that was used primarily to do top icing to loads prior to their departure. For these types of loads that meant extra switching moves and time delays prior to the load departure. Top icing capabilities and the apparatus that went with it are also a consideration when modeling the packing sheds themselves as the chutes in your photo show.

    Another modeling consideration for the 1946 and later period would be the vacuum cooling facilities. With their use you move away from shed packing to primarily field packing. You then have the cooling tubes between the field package unloading spot and the trackside loading site. The first of these cooling tubes measured 5 ft in diameter and 8 feet long. These could handle 16 crates at a time. The next iteration of tubes (late 1940's) went to 40 feet long and 7.5 feet in diameter and could hold 160 cartons at a time.

    By 1954, there were 9 vacuum cooling plants in the Watsonville-Salinas district, and the lettuce loading had switched completely from iced wood crates with top icing to un-iced, fiberboard cartons with no top icing.

    Greg Henschen

  2. Thanks for the extensive information, Greg. This supplements what I summarized, and I guess I was maybe too brief. But I do have a few comments to make on your material.

    You are right that top icing helped remove field heat, but an equally important reason, and probably more important, is that it kept produce from drying out. Otherwise, why would top ice be repeatedly applied throughout transit, as in fact was done with leafy vegetables?

    I was aware that crushed ice was sometimes put into shipping crates. But the idea was for it to fall into the gaps among the produce items, not actually bulge the crate, because if the latter was the case, the crate would get smaller in transit and begin to move around in the car (and couldn't readily be replenished). I don't believe any bulging crate, whether of oranges, lettuce, or anything else, was that shape because of internal ice, though as I said, internal ice may well have been in the crate when loaded.

    You are entirely right that precooling facilities make a nice modeling opportunity, as does the need to top-ice a load prior to departure (though usually this would accompany bunker icing, unless the ice deck was so small that top icing had to be done in a separate location).

    The change to cardboard cartons happened at different times for different commodities, and probably varied by area. The early 1950s photos I have seen of California packing do show wooden containers in all cases, so I haven't pursued research on the advent of cardboard.

    My interview with PFE's retired Car Service AGM, Pete Holst, touched on some of these issues, and he stated that growers were eager to move toward field packing as early as the 1920s, but that the need to clean most produce, plus the fact that the personnel who sorted produce by size and quality were very different people from field hands who did picking, prevented much of that before the 1960s.
    Tony Thompson

  3. Tony,

    The use of wooden pine crates was the accepted method of packing lettuce from 1916 until about 1952. The standard wooden crate size used was 13 3/4 x 17 1/2 x 21 5/8 and held about 48 to 60 heads of lettuce. The typical reefer held 300 to 320 of these standard crates. The loaded crates weighed 70 to 110 pounds each so there was roughly 14 to 16 tons of lettuce per car. Until the late 1940's the top icing method was standard for lettuce loads. Top icing added $60 of cost (1948) per load, but helped provide 32-40 degree temperatures for the entire trip and provided insulation around the top and sides of the crate stacks. It also provides added moisture, as you pointed out, but I could find no mention of this as a benefit in my research. The crates already had ice within them from packing to provide moisture.

    With the top icing you have the ice bunker weight and the top icing weight totaling around 15 tons Add this to the cargo weight and a 30 ton Reefer is just about maxed out with lettuce and ice. You could assign 30 ton or 40 ton reefers, wood or steel, to handle these top ice loads. P.F.E. cars and most others were not a problem with this kind of weight, but some reefers of the time period (F.G.E.) lacked even the 30 ton capacity needed for this kind of load.

    In the late 1940's, when they figured out how to remove field heat with the vacuum process, things evolved. Initially, the crates were still used and still had ice added to them. It was about this time that the railroads started offering fan equipped cars that promised more uniform cooling while en-route. Experiments began with shipping the crates without top icing but using the fan equipped cars. This proved successful and allowed the shippers to save $60 per car in top icing costs. Now if you wanted to ship lettuce, without top ice, you had to have a fan equipped car and the bunker ice maintenance became more critical to preventing shipment loss than with a top iced car of lettuce.

    By the early 1950's, experiments with the use of fiberboard cartons were underway. These were tried as a replacement for the wooden crates. The early fiberboard cartons did not handle water well, so there used dictated stopping the practice of adding ice to the packed lettuce. Adjustments to the vacuum cooling process allowed the lettuce to be packed without ice and without top icing, but the fan equipped car was still a must for this type of shipment. The use of fiberboard cartons took off and the wooden crate use declined accordingly. Interestingly, some cargoes still required ice packing in the container so wax coated cartons were devised (mid-late 1950's) to handle artichokes and other cargoes that still required this crushed ice packing.

    Hopefully some of this will help provide information for making out your lettuce load waybills. It also should stimulate some thought about some of what went into car assignment.

    P.S. I did find out that county inspectors would "red tag" an entire load if they found the wood crates bulged more than three inches. I also found that express cars were occasionally used for lettuce delivery. The surcharge was $1.50 per crate (1948), but New York deliveries could be done in 4-5 days instead of 9 days via regular P.F.E. shipment.

    Greg Henschen

  4. Thanks again for much useful and interesting detail, Greg. I would add just a few comments. PFE was aware of the benefits of car fans in the 1930s and experimented with several types, adopting none of them. But that experience base enabled them to recognize the virtues of the Van Dorn patent fans when that product emerged (marketed by Preco), and PFE promptly adopted them for new and rebuilt cars. That's discussed in the PFE book, page 129, and literature citations are available in the Bibliography section of the PFE book.

    I should also note that Greg's comment was submitted on July 27, 2011 but was for some reason caught in Google's spam filter, and when I discovered that today, I moved it out of the filter. My apologies to Greg and to readers for the confusion.
    Tony Thompson

  5. Wooden packing crates started to be phased-out of packing houses in the early 1950s. By 1954, this transition was almost complete in Sunkist packing houses. In that year, 90 percent of the lemons and nearly as large a percent of oranges and grapefruits were shipped in cartons. Beginning in the 1955-56 fiscal year, all Sunkist orders, quotations, accounting and other records switched from a “box” to a “carton” basis. The standard carton has one-half the capacity of the wooden packing crate.

    In 1961 Sunkist’s Fruit Growers Supply Company partnered with Crown Zellerbach Paper to begin producing cartons at adjoining plants in the City of Industry. Fruit Growers Supply Company (a Sunkist subsidiary) eventually built its own carton plant in Ontario in 1979.

    So why did the packers replace wood crates with corrugated fiberboard cartons? Part of it was economics. Cartons required less labor to manufacture and eliminated crate-making machinery in the packing houses. Cartons also simplified automation in the packing houses. Another reason was the rise of self-service supermarkets after World War II. Retailers, according to Sunkist, wanted to have commodities available in lighter containers. At half the loaded weight of a wood packing crate (due mainly to holding half the volume of fruit) the cartons fit this requirement nicely.

    Bob Chaparro
    Hemet, CA

  6. Thanks, Bob, for some good information. I have the impression that the arrival of cardboard cartons to replace wood crates was at different times with different commodities. I have a photo of cauliflower being loaded at Guadalupe in wooden boxes in 1955. But obviously a modeler needs to know when such transitions happened in his or her own modeling period.
    Tony Thompson