The ARRC Glacier Discovery crosses ARRC Br 86.6 (Bird Creek) southbound on August 20, 2024.  

The main span of Br 86.6 is one of the military surplus pony trusses, originally fabricated for the Army in WWII and designed for quick erection behind the advancing armies in Europe.  The ARR originally located this span with two others on the Knik Flats (Br 147.1).  That 3 span bridge was removed in the 1990s and this particular span was relocated to Bird Creek about 1995.

The ARR installed 21 of these pony truss spans throughout the system.  But they are wearing out.  This span is scheduled to be replaced by early 2025, eliminating these pony trusses from all bridges with track speeds over 25 mph.  The 11 other remaining spans will follow eventually.