![]() ![]() Located between the 3rd Avenue Bridge and the I-35W Saint Anthony Falls Bridge, the Stone Arch Bridge was built in 1883 by railroad tycoon James J. 117 Portland Avenue is the general address of the historic complex. The bridge was completed in 1883, costing $650,000 at the time ($20.4 million today). The bridge was built to connect the railway system to the new Union Depot, which at that time was planned to be built between Hennepin Avenue and Nicollet Avenue. It is the second oldest bridge on the river next to Eads Bridge. It is the only arched bridge made of stone on the entire Mississippi River. ![]() The Stone Arch Bridge is a former railroad bridge crossing the Mississippi River at Saint Anthony Falls in downtown Minneapolis, Minnesota. Anthony Falls Historic District ( ID71000438 ) In some cases additional cribbing or raised parapets must be added to keep the ballast from overflowing to whatever lies below the bridge.St. ![]() And interesting maintenance-of-way side effect of this is that the ballast depth over solid decked bridges will increase over time due to ballast renewals and tamping. If that minimum distance is succeeded, then the length and thickness of the tie must be modified accordingly.Īs already noted by previous postings, bridges with solid floors are treated the same as normal roadbed from a ballast perspective. ![]() I suspect (and it's just an assumption) that that minimum spacing is for stability. In short, the rails on a deck girder bridge are not directly over the girder, which have a minimum recommended spacing of 6'6". The fact should be recognized that the tie acts as a beam, and as such must withstand bending and shearing stresses, support the rail load and transfer this load to the stringers or other supporting members of the floor system." The ordinary thickness of tie should be varied in accordance with the span width between supports. The length should, in any event, be not less than the total distance out to out of supports, plus 12 in. the deck girders in your example - Matt), should not be less than 8 in. "Ordinary ties, of uniform dimensions, for one track, with a maximum distance of 6 ft. I looked up bridge floors in a 1929 Maintenance Cyclopedia, and found the following on page 531 of the Bridge Floors section, which addresses your question about tie length (as well as the closer spacing, which Douglas also commented on): As I said either case the ties on a bridge are usually longer to hold the guard on the outside. On a ballasted bridge there is a full deck of some sort on the bridge that is holding the weight so the ties are fully supported across there whole width so the are not carrying any actual load so they are basically the same as ties on the ground. Normally the rail is directly above the girders so the weight is carried straight down but in a derailment the load moves over so the ties have to actually hold the weight. Also the tie has to be strong enough that if the car or engine derails on the bridge the ties can hold the weight. The open bridges used ties that are larger because the tie is only supported by the girders it sits on so all the weight the tie has to hold is applied in only a small area so the tie is made larger in part to make this area larger. I need to determine if I need to purchase more bridge track for the Double Track Stone Arch Bridge or not, because as of this moment I don't have enough and last time I had to order it, it took over 6 weeks to get it to me from an online vendor! So I am hoping the answer is "no" I do not need Bridge Flex Track, I can use regualr Flex Track and ballast the track on the bridge.Īs far as I understand it if you have a ballested deck then you use regular ties (w./d.) But usually longer as their is normally a wood or metal guide on the outside to try and keep a derailed car on the bridge. Though that is not the primary purpose of this thread. Doesn't the weight being carried just go through the ties onto the steel members? Obviously it's an engineering issue as to why, but I was wondering if anyone could explain to someone who has a hard time grasping calculus therefore most engineering questions are beyond my comprehension why the need for the additional ties, and why are they wider than normal ties. One thing I have not quite grasped is why the need for the additional width and ties on "open deck" type bridges. I could have sworn I asked this question before, and if I did it was not on this forum (and going through the many different discussion groups I used to belong too will be too time consuming unfortunately instead of just asking those who have a similar type of bridge, would the track on a Stone Arch Bridge be Ballasted or not? And if it was ballasted (because I presume the structure underneath was designed or resulted in having a surface to have ballast, there would be no need for the additional ties or the extra width "bridge" ties on such a bridge, correct? ![]()
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