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Model Railroading > BNSF 72’ Frostline Reefer (Part 15) – Stop the Presses

Date: 12/02/22 00:24
BNSF 72’ Frostline Reefer (Part 15) – Stop the Presses
Author: tmotor

This is Part 15 of a series on the BNSF 72’ Frostline Reefer project.  (Parts 1 thru 14 were posted earlier.)
News Flash
In Part 4 of this series, I stated the first batch of Frostline Reefers lacked insulation on their undersides.  This was an assumption based on the Plug Doors lacking external insulation.  As it turns out, ALL Frostline Reefers with a plastic roof also have insulation sprayed onto the underside of their floors.  So, regardless of whether the Plug Door has exterior insulation added or not, it if had a plastic roof, its underframe has been sprayed with foam. 
Trinity was pushing the state-of-the-art with insulation on the Frostline Reefers.  An educated guess for the difference in Plug Doors is: YSD was approached by Trinity for a Plug Door with external insulation, to increase the insulation factor even more.  However, BNSF didn’t want to wait for the new Plug Doors, so standard Plug Doors were used for the first batch.  Meanwhile, YSD was still modifying their Plug Door to accommodate the external insulation. When the new externally insulated Plug Doors were available, they became the design used for the remainder of the Frostline Reefers (until the Econo Frost version). 
I have updated the chart from Part 4 as follows:
Percent                                             Frostline                                           Underside        Fuel
Of Fleet          Description                   Graphic         Door            Roof          Insulated         Tank
-------------    -----------------------   -------------   -------------  -------------  -------------  --------------
    18%           Original                         Yes           Standard        Plastic            Yes           Cylinder
    42%           Insulation Upgrade         Yes           Insulated        Plastic            Yes           Cylinder
    11%           Defrosted                     Noooo!       Insulated        Plastic            Yes           Cylinder
    29%           Econo Frost                    No           Standard      Metal Rib           No           Rectangle
I placed a GoPro video camera between the tracks.  When the train passed overhead, it gave a brief view of the underframes.  Though the images were not clear enough for modeling purposes, by pausing the video, it does show the presence (or lack) of foam insulation.
BTW, in case you are wondering why a spine car comes after the string of Frostline Reefers, BNSF routinely runs Frostline Reefers on intermodal trains.   Their perishable cargo makes them high-priority freight.
Back Plane Purpose Confirmed
The application of foam since Day-1 implies the Frostline Reefer design had insulation as a top priority.  In the previous post (Part 14) I suggested the incorporation of the Back Plane was to create a thermal break, so the brake wheel and gearbox would not add heat to the outside skin.  Now that I see the undersides were sprayed with foam from the very beginning, this seems to confirm the purpose of the Back Plane is indeed to keep one more source of heat away from the outer envelope.  All Frostline Reefers with a plastic roof had their brake wheel gearbox mounted to a Back Plane.  This will reduce fuel costs, since the reefer unit will be running less often.
The highly efficient insulation must have had a good track record.  After 2 decades of running side-by-side with the Econo Frost version, direct comparisons of fuel consumption would be easy to obtain.  It is one of the reasons BNSF went to the expense of replacing the plastic roofs, vs. getting new reefers.  Though the roofs fell short of expectations, the Frostline Reefers’ hyper-insulated design proved to be a winner in the battle for better fuel economy. :-D

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