The thread about Rio Grande dual gauge remnants brought to mind a find up at Alturas in northern California. The old N-C-O was converted to standard gauge in the late 1920 and during this conversion both 3- and 4-rail dual gauge was used.
A couple of years ago -- in June of 2008 -- a group of members of the N-C-O Yahoo email group gathered in Alturas to check remnants of the narrow gauge. Right next to the old depot (now a woman's garden club headquarters) several ties with spike holes from a 4-rail set up were observed.
Left to right: Frank Ackerman (Curator of Education at NSRM), unknown, unknown, Jerry McGowan with measuring tape, Tom Armstrong leaning over with camera with straw hat and tie, and Paul Martineau.
Brian Norden