Do stone structures like the Starrucca Viaduct require much in the way of maintenance? I was reading the article in Trains about the steel Portageville Bridge being in need of upgrades or even replacement to handle current loads…but one never hears about those stone bridges which were apparently built to handle much greater weights.
The Rockville bridge over the Susquhanna river has been around since 1905. It was originally triple track and now is down to double track. As far as I know except for the usual maintenacne on the bridge there has never been a major repair made to the bridge. It has handled all of the locomotives and cars that crossed it without any structural problems.
It has survived many heavy ice flows against its arches and stood up well for all of these years.
Stone bridges are most generally arches. All other things being equal, the more weight you put on them, the stronger they are.
If the stones all fit properly, and any method of joining them (mortar) is in good shape, they should last forever. If the stones don’t fit together properly, or something causes them to shift, there could be trouble.
The bigger problem with such a bridge may be its foundation, which in the case of a river bridge, could suffer erosion.
Regular inspection is still a key.
Not my area of expertise - it’s a real specialty - but from what I’ve observed:
Mostly just ‘re-pointing’ the masonry between the stones every few decades.
The most common threat is undermining of the piers during flood conditions, which can happen to any type of bridge with piers in the stream. The former GN’s James J. Hill bridge in the Minneapolis-St. Paul area had that happen to one of its piers in the late 1960’s or so - you can still see where that pier settled about 9’'. A downstream ‘cousin’ to the Rockville Bridge - the ex-PRR Shocks Mill Bridge, also across the Susquehanna River - lost something like 9 or 13 of its arches during the 1972 flooding by Hurricane Agnes, which were replaced by steel girders.
Actually, about 15 or 20 years ago the southern side of one of the piers of the Rockville Bridge collapsed under a coal train, and put a couple of hopper cars into the river. Apparently the ‘core’ of the piers isn’t solid rock, or cemented together, or else it had deteriorated pretty badly and failed. There are some photos on-line that show the resulting ‘patch’.
Another related repair or upgrade I’ve seen is like retaining brackets on each side of a pier with bolts either through the pier or on each side of it - probably to prevent the same thing from happening.
Many of the old PRR stone bridges along the Middle Division and
A brick you-know-what-house is paper compared to the likes of Starrucca! Originally no morter but has been pointed several times since its 1848 completion. Concrete, like Tunknannock nearby, also has a good shelf life with a little more maintenance. But things were built beyond the needs of the times of these two bridges built about 60 year apart. THis kind of building and engineering lasted throught the 30s anyway. I use CCC highway bridges which have crumpled, but then the loads they endured have been far beyond the wildest dreams of the 30’s builders anyway. Starrucca built for a double track railroad…double 6 ft. guage track that is…today it is single track standard guage and sees only three trains each way each week now. Tunkhannock can see up to twice that many in a day on single track. They do stand up well but owners Erie and Lackawanna took better than great care of them when they were around…today’s owners keep a wary eye on things but are sure history has given them a gift.
As for how long these bridges might last, the Romans, who extensivelyemplyed, actually developed the stone arch bridge, constructed stone arch bridges that are still in use today. I suspect that the Ponte Vechhio in Rome will still be in use long after our cantlever and suspension bridges are long gone. The old PRR, now Amtrak, bridge over the Delaware at Trenton has four tracks and sees an endless parade of NJT Transit, Septa, Amtrak and CSAO day and night. It’s as sound as the day it was completed over a hundred years ago. Maybe 2,000 years from now these bridges will be remembered as examples of what American (nee Roman) engineering could do.
Maintenance matters, especially drainage, and especially drainage in areas which are prone to frost or sub-freezing temperatures. Water expands on freezing and that pushes the stones apart.
Of like kind to Starrucca and the Trenton bridge is the ex-B&O’s, now CSX Thomas Viaduct at Relay Maryland, across the Patapsco River - which is on a pretty respectable curve, too, unlike all of the others mentioned so far. I believe it was started around 1828, completed 1832 or so. Today it still carries a pair of very busy mainline tracks.
William D. Middleton in his book Landmarks of the Iron Road also mentions the many stone bridges on the Boston & Albany line on the eastern side of the big summit there. As I recall, they were designed and their construction supervised - along with the rest of that line - by an early railroad engineer, George Washington Whistler, and several of those are still in use today.
- Paul North.
The Maidenhead Bridge across the River Thames in England is one of the first built for railway use, and it is still very much in use today.
Believe for much of the Rockville stone arch bridge’s existence, it supported 4 tracks…then down to 3, and now 2. Changes for various reasons.
Item: Just some thoughts on stone arch bridges.
It seems to me if a bridge has certain absolutes, such as piers solidly structured down to proper bed rock…proper pier facing design to reject down stream moving obstacles, {ice, etc}…proper engineering arch design…and correct kind of rocks {strength}…and if somehow it would be {still}, possible to fit each to the other with total surface contact, as we’ve seen in historic structures at various locations in the world…and correctly protected by drainage on it’s deck…Might we have a bridge {perhaps without mortar}, to stand until something like an act of God destroys it.
A little more on the Rockville Bridge : After looking at some oblique or “bird’s-eye” views of its southern side, I believe that damaged pier from back in the ConRail days of the early 1990’s is about in the middle, maybe a couple hundred feet west of a signal mast.
Quentin/ modelcar, your proposition above is essentially correct, I think - get it all right, and a bridge like that could last a very long time. Kind of like the answer to the question of “Have you lived here all your life ?” Answer: “Not yet !”
And I expected you to have something to say about the durability of the famous stone bridge at Johnstown ?
One natural force/ event that stone bridges are not particularly good at resisting, without a lot of special precautions and reinforcing - earthquakes. But then, very few large man-made structures are.
- Paul North.
The keys to the survivability of a stone structure -beside good engineering design- are solid foundation, careful construction in the placement of stones, and in the case of walls, exact plumb to verticle. After that, good caps or roof to cover the tops of the walls and tuckpointing to keep water from getting inside the walls.
I live in a house with 18 inch walls (24 inch foundation walls) made of limestone held together with lime and sand mortar. The tallest walls have parapets at the gable ends of the three story part of the house and they rise about 36 feet from the ground. A local mason is a has become specialized in the building and maintenance of these kinds of walls. Do to some poor repairs performed in the past he is replacing some stones and all the exterior walls are being repointed. He says good tuckpointing should last at least 50 years and as evidence has indicated some sections of the walls with original pointing still intact.
Our house is a 168 years old. We don’t run any trains over the top of the house so I think we’re good to go for another century or two.
Look at Thomas Viaduct on CSX. Originally built by the B&O in 1840 and still used daily today.
The photo in this link shows pretty well what I believe is the pier of the Rockville Bridge that collapsed and the subsequent repairs, as well as 2 different kinds of the brackets/ bracing on the 2 piers on each side of that one:
http://www.railpictures.net/viewphoto.php?id=342437
- Paul North.
Yes, in view of this discussion, I have been thinking about the famous PRR stone arch bridge in Johnsown…so famous in the 1889 flood.
We pretty much know it’s history from the media history of the flood, etc…and so on.
So it certainly did have excessive strength to survive that experience.
Item: If I remember correctly I’m thinking on it’s south side…many years ago, it was added to by concrete extension to make it wider…{some time after the flood}, to accept more tracks. I believe that is correct.
…That certainly is a good dramatic photo clearly showing the repair at the problem arch.
Item: The size of that stone arch bridge makes me think of the massive quanity / quality of rocks that had to be located and transported to the sit
The Chicago & North Western has a stone arch bridge in Rock County, WI (ca. 1855?), that was reinforced with concrete arches under the stone course (ca. 1935?). I would guess that, after a point, the ring of the arch can get thin enough that it would buckle under the weight of a load that is not yet fully across the span.
IIRC, the Rockville Bridge is backfilled with gravel/dirt/ballast or something (the fluid nature of which was suspected of causing the sidewall collapse) and the Thomas Viaduct was backfilled with concrete sometime in the 1920’s (?). The DL&W’s concrete arch bridges would be solid, I expect.