Re: Como snowstorm - September 8th.

Como Wrote:
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> How long would a Trestle be expected to last? How often did they need to be replaced?

It depends on the materials used, climate and the amount of traffic over the span. In the old days, railroads repaired/replaced defective parts when they didn't pass inspection or failed from storm damage, etc. A complete bent could be pulled out and rebuilt in a few hours in most cases. Stringer replacement took longer since the rails had to be lifted for the work. A good example is the Maryland & Pennsylvania Railroad that had 111 wooden trestles in 77 miles of mainline. Most trestles were rebuilt to nearly new condition when the line was converted to standard gauge in 1900 - '01. Some of the spans were upgraded with steel stringers for the larger consolidations in 1914 - '15 but most of the trestles stayed in service as built for over 50 years in Maryland and 70 years in Pennsylvania.

Trestles were inspected every year. Some needed work while others could be good for 5 - 15 years. A wooden trestle with light traffic (weekends only in Summer) in a dry climate should be good for 20 - 30 years with minor adjustments every year or two. There's a two bent trestle on the WW&F that is 19 years old and other than an adjustment to the south abutment sill the span passes inspection each year, is in very good condition and can handle any size locomotive that runs the line. Modern timbers have better weather proofing and fire protection than they did years ago so a trestle built to old plans with modern materials will provide years of good service.