Getting to the Bottom of Stone Culverts
by Ronald J. Stanulevich
Photos by Ron Vassallo
The following came from correspondence I had with Ron Stanulevich via the Yahoo Group in 2003 after posting some culvert photos I had taken between Mamakating and SV.
These photos were taken on Saturday September 27, 2003 by Ronald J. Vassallo. All of the culvert photos except Culvert 7, were taken on the mainline north of the Bloomingburgh Tunnel between Wurtsboro and Summitville. Culvert 7 was taken on Red Hill Grade. The bridge, canal and structure photos were taken on the PJM&K Branch.
The following is the original unedited response from O&WRHS member Ron Stanulevich, and no I did not crawl in any of the culverts as suggested by Ron, (read on), except the larger ones. I hope to go back in the near future and re-shoot some of these in better detail.
I guess maybe one has to be an engineer and/or a railway historian to truly appreciate the aesthetics of drainage culverts, but anyone with any interest at all in vintage railroad RoW construction should follow the links in the "files" area to the amazing pictures of the culverts that Ron posted. You are in for a real treat.
Back in the early steam era, before poured concrete was widely available, stone was the only viable material from which to create lasting, high-carrying-capacity railroad structures. (Wood was biodegradable in railroad applications, and even cast iron was relatively brittle and prone to corrosion by water.) The New York & Oswego Midland built some true marvels in stone that seem to only get better with age.
Good seamless building stone lasts essentially forever when placed solely in compression, so true arch culverts are virtually indestructible as long as they were properly designed and built to prevent their being undermined by floodwaters. Stone slab culverts have the top slab carrying some shear tension loads, so some of the larger slab culverts could and did eventually crack and fail. Smaller slab culverts also lasted essentially forever, like good arch culverts. With that background as introduction, two of the photos in Ron's culverts file merit special mention --- one big culvert and one small.
Big: Photo C7 (Left) is as perfect an example of a large stone arch culvert as you could ask for. Talk about combining visual appeal and pure function. Look at the height of the embankment this structure is still successfully carrying. (Did you measure the opening size of this one, Ron?) It is still in virtually as-new shape after 130 years, the last 50 with no maintenance attention at all. Even modern cast concrete structures would not be in this good condition after this many years, having had the porous surface spalled off and cracked by frost action decades ago.
Small: Photo C2 (Left) shows about as small a stone slab box culvert as would ever have been built on a railroad. Engineering texts warn against building box culverts with clear spans under two feet square, on account of their being certain to immediately plug with drift and subsequently wash out. I guess this ancient culvert never read a modern engineering text.... No formal Japanese stone garden ever held a more appealing little monument to the spirits of our departed (railroading) ancestors.
To complete this tribute to the arcane, I'll conclude with this observation. While culverts may seem to be simple and straight forward structures, they are actually a bit like icebergs --- most of the really interesting and important bits are hidden underneath the surface. Well-engineered culvert like these examples, capable of lasting over a century, have any number of well-kept and subtle engineering secrets in their construction, buried below and behind what you see at the ends. If you asked a layman to draw a guess at the cross-section of a culvert like this, they would leave out about 50 percent of the stone that is really in there.
Ron -- your next assignment, should you choose to accept it, is to go back to these culverts with a set of powerful, portable camera lights, a good SLR, lens, and a fiber optic probe. Crawl through the bore from one end to the other, taking a complete set of photos of the inside, top and bottom and underneath, as you go. These pictures will answer all of my many questions about which of the several complex and fascinating engineering options the Midland selected in designing and building its stone culverts. Which of the available engineering choices would provide the longest service life was a hot topic of debate in the engineering fraternity, way back when these culverts were built and the science of railway engineering was young. I think the Midland builders obviously made all the right choices, and knowing which design options they used would settle that ancient engineering argument, once and for all.
Thanks for posting these, Ron.