Re: Maintenance - Steam vs. Diesel

nedsn3 Wrote:
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> I'd add one more to the above comments: steamers
> were hard on track.

And the railroads built the infrastructure -- like bridges -- to account for that.

A couple of years after the double-stack, articulated (shared truck) container cars came out, I read an article about bridges in a publication for track maintenance people. These double stack cars were inducing a heavy axle loading on bridges. This was particularly bad on short spans that were shorter than the truck spacing. This short spans would be loaded and then unloaded and this was putting stress on the girders and the joints (pins, rivets, etc) and causing metal fatigue. Longer spans that would have the next truck on them before the first one was off were doing better, but still a concern. The railroads were adding extra girders and such under the bridge to increase weight carrying capacity. The bridges built during the steam era were generally over-built and were not suffering from fatigue.

BN