Looks like 1" scale, 5" gauge to me.
Prototype Rail Sizes (in inches)
. 90# 100# 110# 120# 130# 140# 150#
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Height 5 5/8, 6, 6 1/4, 6 1/2, 6 3/4, 7, 7 3/4
Base Width 5 1/8, 5 3/8, 5 1/2, 5 3/4, 6, 6 1/4, 6 3/4
Head Width 2 9/16, 2 11/16, 2 25/32, 2 7/8, 2 15/16, 3, 3 1/8