Duncan Tunnel

{{Use mdy dates|date=April 2025}}

{{Infobox tunnel

| name = Duncan Tunnel

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| other_name = Edwardsville Tunnel

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| location = Edwardsville, Floyd County, Indiana

| coordinates = {{coord|38|17|22.5|N|85|55|07|W|scale:1500|display=title}}

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| opened = 1881

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| operator = Norfolk Southern Railway

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| linelength = 4,295 ft

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The Duncan Tunnel (also known as the Edwardsville Tunnel) is a railroad tunnel in Edwardsville, Floyd County, Indiana, USA. At {{convert|4295|ft}} long, it is the longest tunnel in Indiana. The tunnel was initially built for the Air Line, who were unable to find a suitable route over the Floyds Knobs, so they decided to tunnel through them.[https://pbase.com/image/51422595 Photo] The tunnel was completed by the Southern Railway in 1881 at a total cost of $1 million.[http://www.sunnysideoflouisville.org/history/history.htm Sunny Side of Louisville - Area History] {{webarchive |url=https://web.archive.org/web/20101223070043/http://www.sunnysideoflouisville.org/history/history.htm |date=December 23, 2010 }} It is still in use by the Norfolk Southern Railway.[https://books.google.com/books?id=G8sddkoqS-gC&dq=duncan+tunnel+indiana&pg=PA89 Railroad Depots of Southern Indiana, By David E. Longest.] Pg 89. {{ISBN|0-7385-3958-9}} The tunnel passes beneath I-64 intersection #118.