12-02-2009, 10:23 AM
Yeah, I'm late to the game...
The issue for such a structure isn't total weight, but the weight distribution. For example, while their total weights are close...an Allegheny is far more of a nightmare on trestles than a Big Boy (slightly more weight distributed over few axles). The name of the game is Cooper Bridge ratings. I suspect that those lighter diesels would raise more havoc than 2-8-0 on spans approx the same length as the trucks.
Similarly, IIRC the axle loading issue was part of the reason why the CN used 4-8-4s while the CP used 4-6-4s (which had slightly higher axle loadings)...lower track/bridge standards.
My On3 trestle uses 8"x8" timbers set at 12" on center for ties. I'd run any decking perpendicular to them if I was turning it into a pier.
Many west coast narrow gauges ran their locomotives out on piers; the Pacific Coast Ry and North Pacific Coast were excellent examples.
The issue for such a structure isn't total weight, but the weight distribution. For example, while their total weights are close...an Allegheny is far more of a nightmare on trestles than a Big Boy (slightly more weight distributed over few axles). The name of the game is Cooper Bridge ratings. I suspect that those lighter diesels would raise more havoc than 2-8-0 on spans approx the same length as the trucks.
Similarly, IIRC the axle loading issue was part of the reason why the CN used 4-8-4s while the CP used 4-6-4s (which had slightly higher axle loadings)...lower track/bridge standards.
My On3 trestle uses 8"x8" timbers set at 12" on center for ties. I'd run any decking perpendicular to them if I was turning it into a pier.
Many west coast narrow gauges ran their locomotives out on piers; the Pacific Coast Ry and North Pacific Coast were excellent examples.
Michael
My primary goal is a large Oahu Railway layout in On3
My secondary interests are modeling the Denver, South Park, & Pacific in On3 and NKP in HO
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My primary goal is a large Oahu Railway layout in On3
My secondary interests are modeling the Denver, South Park, & Pacific in On3 and NKP in HO
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