Glengarry5 | 15 Dec 2020 7:21 p.m. PST |
I'm thinking of getting a covered bridge model for my ACW/BIF games. I'm curious as to why it was thought important to cover your bridges for roads and railroads in the first place? I heard a story that bridges were covered to prevent horses from getting spooked like they often did when crossing open bridges. But why covered bridges for railways? Was it to protect the trains? Protect the bridges from weather damage? Flood damage? |
Sundance | 15 Dec 2020 7:26 p.m. PST |
They were covered to protect them from the weather so they would last longer. |
BTCTerrainman | 15 Dec 2020 8:30 p.m. PST |
As Sundance indicated, it was for protecting the bridge and reduce the effect of weathering. The technology was not available to protect wood from the effects of weather. The hope was to allow a bridge to last a lot longer than normal wear and weathering would allow. There are quite a lot of covered bridges left and many outlasted more modern bridges. |
HMS Exeter | 15 Dec 2020 8:39 p.m. PST |
Inasmuch as the bridges span open air, in freezing temperatures, uncovered bridges are more susceptible to icing in sloppy weather. If a covered bridge's roof ices up, who cares, so long as the deck is dry and clear? |
Wackmole9 | 15 Dec 2020 8:40 p.m. PST |
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Wargamorium | 16 Dec 2020 2:14 a.m. PST |
I thought it was to strengthen the bridge and prevent it from sagging. |
mildbill | 16 Dec 2020 7:29 a.m. PST |
HMS Exeter is correct. Bridges were covered so that horses could cross in icy conditions. Wood ices up very quickly and iron shod horses would fall on uncovered wooden bridges. |
DyeHard | 16 Dec 2020 9:05 a.m. PST |
I think everyone is right! It would be fun to find design notes to confirm the reasoning, but the covered bridge had several advantages over an open wooden bridge. The box shape is stronger, but costs a lot more to build. The roof protected both the structure as well as uses from rain and, more impotently snow. The cover help reduce icy of the bridge deck. In the USA you can still see warnings of icy bridges as cold air tends to move along rivers. This helps explain the cladding on the side of the bridges. Now icing could be overcome by placing grit on the bridge deck, but that would hasten the damage to the deck, shortening the life of the bridge. |
Bill N | 16 Dec 2020 10:49 a.m. PST |
Sundance and HMS Exeter are correct. Even if covering the bridges had little long term benefits, the assumption at the time was that it did. Since they were used down south as well as up north I doubt it was just ice they were worried about. Covered railroad bridges in general had nothing to do with protecting the trains in transit. Railroad bridge builders started out simply borrowing the prevailing road bridge building technology. When it was realized that the cost or building covered bridges was higher and that the damage from train operation was a bigger factor in bridge longevity than the weather, railroad bridge builders moved away from them. I suspect there may also have been a fear that covered bridges were more likely to catch fire from the passing trains, but I have not read anything specifically on this. That said in the late 18th century certain railroads out west began building snow sheds, essentially covered bridges on ground. These were done more to keep railroads open in areas where heavy snow and avalanches were common rather than protecting the trains themselves from exposure to the weather. |
raylev3 | 16 Dec 2020 5:09 p.m. PST |
they were designed to keep ice and snow off the bridge. Easier to cross, and the sloped roof kept the weight off. This is why there were far more covered bridges in the north east. They were relatively rare in the south. |
rmaker | 16 Dec 2020 5:29 p.m. PST |
Since they were used down south as well as up north I doubt it was just ice they were worried about. Freezing conditions are not unknown in the South. When my business partner and I exhibited at the HIA show in Atlanta, there was an overnight ice storm. We were proceeding from the motel to the downtown convention center at a sedate 40 mph and were pulled over by a Georgia State Trooper, who asked,"Don't you think you boys are drivin' a little fast?" My partner pulled out his driver's license and handed it to the trooper. He looked at it and said "oh, you're from Minnesota. You know about this crap. But watch out for the red necks. They ain't got a clue." |
EJNashIII | 16 Dec 2020 8:38 p.m. PST |
wargamorium, more coincidentally. A truss bridge proved stronger than a non truss bridge. Since said truss would generally form a framed space not unlike a house or barn in shape, it was a small jump to putting a roof over it. |
EJNashIII | 16 Dec 2020 8:51 p.m. PST |
one thing that we generally miss about covered bridges. Most surviving examples are out of the way minor bridges. Many of the more significant ones were a bit more architecturally interesting than one would imagine. For example, the famous one burned at Harpers Ferry was of an Egyptian motiff. |
Murvihill | 17 Dec 2020 10:10 a.m. PST |
According to the Federal Highway Administration the primary reason was to protect the bridge, not the travellers: link |
138SquadronRAF | 17 Dec 2020 12:25 p.m. PST |
Interestingly enough, in Europe covered bridges are uncommon outside of Switzerland and Southern Germany. |
AICUSV | 22 Dec 2020 12:26 p.m. PST |
Living in an area noted for its covered bridges, we have always held it was to protect the road surface from the weather. Even just wet wood planking can be slippery to an iron shoed horse. As to RR bridges it may well be for strength, but iron wheels on iron rails with water in-between can prove difficult. Also Bill N -I think you meant 19th century RRs. |