The Duncan Tunnel is a railroad tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 in Edwardsville

Edwardsville, Indiana

Edwardsville is an unincorporated community in Georgetown Township, Floyd County, Indiana....

, Floyd County

Floyd County, Indiana

Floyd County is a county located in the U.S. state of Indiana. As of 2010, the population was 74,578. The county seat is New Albany. Floyd County is the county with the second smallest land area in the entire state...

, Indiana

Indiana

Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...

, USA. At 4,295 feet 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

Floyds Knobs, Indiana

Floyds Knobs is a small unincorporated town in Lafayette Township, Floyd County, Indiana. Historically a farming community on the outskirts of New Albany, it has since become a bedroom community for Louisville, Kentucky, containing subdivisions, farms, small shopping centers and churches, and...

 so they decided to tunnel through them. The tunnel was completed by the Southern Railway in 1881 at a total cost of $1 million. It is currently still in use by the Norfolk Southern Railway

Norfolk Southern Railway

The Norfolk Southern Railway is a Class I railroad in the United States, owned by the Norfolk Southern Corporation. With headquarters in Norfolk, Virginia, the company operates 21,500 route miles in 22 eastern states, the District of Columbia and the province of Ontario, Canada...

. The tunnel passes beneath I-64

Interstate 64

Interstate 64 is an Interstate Highway in the Midwestern and Southeastern United States. Its western terminus is at I-70, U.S. 40, and U.S. 61 in Wentzville, Missouri. Its eastern terminus is at an interchange with I-264 and I-664 at Bowers Hill in Chesapeake, Virginia. As I-64 is concurrent with...

intersection #118.