Latest post in The Federal Register for Public Comments on the Advanced Notice of Proposed Rule Making for underride protection on Single Unit Trucks (SUTS) includes comments on suggestions for side guards to protect cyclists:
http://www.regulations.gov/#!documentDetail;D=NHTSA-2015-0070-0010
http://www.regulations.gov/#!docketDetail;dct=FR+PR+N+O+SR;rpp=10;po=0;D=NHTSA-2015-0070
