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| Re: A Subway to Staten Island? How a Transit Dream Died (1501011) | |||
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Re: A Subway to Staten Island? How a Transit Dream Died |
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Posted by Michael549 on Wed Jan 23 15:01:09 2019, in response to Re: A Subway to Staten Island? How a Transit Dream Died, posted by Michael549 on Mon Jan 21 11:34:25 2019. From a prior message:"In prior discussions on this forum related to the Verrazano bridge, that in addition to the type of bridge built . . . " Verrazzano-Narrows Bridge - Wikipedia "Verrazzano-Narrows Bridge is a double-decked suspension bridge that connects the New York City boroughs of Staten Island and Brooklyn." "The Verrazzano-Narrows Bridge has a central span of 4,260 feet (1,298 m). It was the longest suspension bridge in the world from 1964 until it was surpassed by the Humber Bridge in the United Kingdom in 1981. The bridge has the 13th longest main span in the world, as well as the longest in the Americas. The bridge marks the gateway to New York Harbor. All ships arriving at the Port of New York and New Jersey pass underneath the bridge and must therefore be built to accommodate the clearance under it.[2]" -------- Civil Engineering - What makes suspension bridges unsuitable for railways - Engineering Stack Exchange https://engineering.stackexchange.com/questions/435/what-makes-suspension-bridges-unsuitable-for-railways What makes suspension bridges unsuitable for railways? "There are a few main reasons why suspension bridges aren't used for railroads. The main reason is that suspension bridges are typically used where very long spans are needed. Trains are very heavy, especially when compared to lanes of highway traffic. This means that long spans require very strong support structures, which in the case of suspension bridges are cables and towers. The second reason goes along with the first; trains cause high dynamic loads as they move along the rail. This can increase the vertical loads by 30%. Third is that trains don't really have suspensions, especially freight trains. This means that any movement in the bridge itself has little opportunity to be dampened before it reaches the train. Suspension bridges are relatively flexible by design which makes transferred motion even more of a problem. You do not want the bridge to be rolling under a train! None of these are impossible engineering issues to overcome. But by the time that you have accommodated all of them, you might as well find a different location or build a truss bridge instead." |
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