Thursday, July 17, 2014

Union Pacific's Arrowedge

In Modular Train Aerodynamics, I observed that stacking double-high container trains so that the cross section is consistent and the gaps are less than 12 feet significantly improves the aerodynamics, and thus the fuel consumption, of inter-modal trains. As more evidence of the importance of the aerodynamics of the trains, Union Pacific has developed what they call the Arrowedge® that is designed to ride as the top container in the first car behind the locomotives.

Union Pacific
Their patents include the "wing" structure designed to make it easy to handle the wedge with standard container cranes.

Railway Gazette
And a railfan has posted a video of it on a train. That video also shows that the gap between units in a 3-pack car is much smaller than 12 feet, but the gap between cars looks like it is over 12 feet.

Update: I contributed to a Facebook posting, but I didn't get any likes :-(

I noticed in this video that they have changed the design. Note this is a UP train on BNSF's former Santa Fe route.
Video @ -1:39 from John Joseph Walsh III posting

Matthew Ginkel posted a train using the newer design near Proviso
Mark Strahlendorf posted
WB to Global at Rochelle,IL 5.19.18 UP 9080 and friends.
Gavin Robey How often do they run with the wedge immediately behind the power?Mark Strahlendorf We saw at least three wedges on Saturday.

Walt Lied posted
UP Aero stacks.

Michael Wayne Sitter posted two photos with the comment: "A westbound intermodal with an ARROWEDGE container passing the Metra yard at Elburn, Illinois on the Geneva Subdivision in September of 2017. -Michael W. Sitter"
Patrick McNamara I don't believe THAT stupidity lasted more than about a year and a half.
Jer Centa I always wondered if the cost savings made up for the operational ones. Wind drag is very real and a huge deal, if something gets you 2-3-4% it's a huge number when you use a billion gallons of diesel a year.
Jonathon Leese Jer Centa Definitely. Same reason you see the extra shrouds, tails and wheel covers on semis. They're not for show.
Ken Schmidt I would think that train make up would matter if they used such things. For example, in that photo, it shows the aerodynamic 'wedge' then two empty spaces behind it.

Now my understanding of aerodynamic principle is nil, but that large empty space behind the wedge could easily create drag, even at that slow speed, and thus potentially defeat the purpose of the 'wedge'. (I am assuming that even at 60 mph there would be wake turbulence created behind the 'wedge')
Dennis DeBruler I've read that the gap needs to be less than 12' to avoid aerodynamic inefficiencies. Three engines pulling just 27 platforms also seems to be rather silly.
I imagine that they were experimenting with different configurations during this time. I’m wondering what the final report was about their usage. Obviously they quit using them but was it due to the wedge not making a difference or was it the precision railroading plan. I haven’t seen photos of these containers stored anywhere or if they were scrapped. I would also have guessed BNSF doing similar studies but they didn’t seem to try it out. It made things interesting for a time though!
Charles Fox Saw one on a chassis at Global I a few months back.

Tom Rutkowski commented on Michael's post

Jacob Masi provided a UP link for more information on the designs.

Michael DeSoi Sr. caught a profile shot of the new design.

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