very nice looking good man great work, after a little hunting I found somethings for you they are from Christopher Nolans The Dark knight Rise plus found a gotham state license plate
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http://www.emergency-planet.com/uploads/monthly_2019_04/tumblr_lu9o3eWV3P1qf8wed.jpg.83953385534985fafde21f62fffee6eb.jpg
Units xml has nothing to do with any of the custom equipment found in mods.
You need to edit the script files. They contain the list of units that have the barricades. The scripts for ballistic shields, guns, and traffic cones also operate on the same logic.