these red-and-white signs were spaced about 100 yards apart

This is Kato item #106-2451

Trainz Product Id: 11413534

Here is an MTH 30-67487 O Pennsylvania 60' Streamlined ABS Full-Length Vista Dome Car

which defines the maximum height and width of rolling stock and engines

Walthers 933-3052 HO Scale CornerstoneSeries Rolling Mill Structure Building Kit VariantsUnitPrice_number_25.50 these red-and-white signs were spacedThis is a Walthers 933 3052 HO Scale Cornerstone Series Rolling Mill Structure Building Kit. Features include corrugated "metal" walls, end door and sidewall cut outs, monitor and round vents, U. S. Steel decals, modular design, interior trusses and caneways, simulated "rails" in baseplate, and includes complete instructions. The finished model measures approximately 16 1 4" x 10" x 10". Condition: Factory New (C 9) Operational Status: Functional