BNSF had a bridge partially burn March 1. Do the RRs have a plan to replace wooden bridges with ones that will not burn easily ?
BNSF bridge in Minnesota damaged after blaze - Railway Track and Structures (rtands.com)
blue streak 1BNSF had a bridge partially burn March 1. Do the RRs have a plan to replace wooden bridges with ones that will not burn easily ? BNSF bridge in Minnesota damaged after blaze - Railway Track and Structures (rtands.com)
To the greatest financial extent - railroads operate on the 'if it isn't broken, don't fix it' theory. If wooden structures are sound and pass routine inspections they will continue to be used. When inspection reveals deterioration that indicates the structure should be replaced - the replacement will normally be accomplished with materials other than wood.
Never too old to have a happy childhood!
If a wood bridge burns or is otherwise damaged unexpectedly, it will usually be replaced in kind in the interest of speed. New piles can be driven fairly quickly and other components such as caps, stringers, etc. are also held as emergency stock. While they might prefer a more permanent replacement, concrete piers take time, establishing a foundation, building formwork and rebar cages, and then pouring the concrete and letting it cure. If a second hand steel or precast span(s) is available that will avoid the need to design and have a new span fabricated.
Steel piles may be used instead of timber, if enough suitable H-sections are available.
As well as faster, replacing with wood is usually considerably cheaper. While the railroads traditionally build for the long term sometimes the line is seen to have dwindling traffic with probable abandonment within the life span of the wood structure.
Timber bridges last normally 35-50 years unless tonnage or natural conditions do something funky. DiningCar and my railroad's choice was to change out the mainline bridges first and replace the branchline bridges depending on tonnage and importance.
The precast concrete sections with steel bents/ piling really came into their own in the 90's with the evolution of concrete admixtures. It's easier to change from timber to concrete under traffic than it is the other way around. Takes slightly fewer people/manhours to build a precast structure than a timber structure.
Timber structures tend to be replaced only when it's time. (I think the E & J Gallo boys got their tag-line from the bridge guys)
As long as the operating departments waste rediculous amounts of $$$ on shiny new toys for little gain in financial performance, the timber bridges will remain out there.
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