1.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
2.
U.S. Route 31
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U. S. Route 31 or U. S. Highway 31 is a long north–south highway connecting southern Alabama to northern Michigan. Its southern terminus is at an intersection with US 90/US98 in Spanish Fort and its northern terminus is at an interchange with Interstate 75 south of Mackinaw City, Michigan. It also formerly entered downtown Mobile, Alabama, via a bridge over Mobile Bay. US31 begins in Spanish Fort, Alabama at a junction with US90 and 98, formerly, the route originated in Mobile, co-routed with US90 and 98. I-65 has effectively replaced US31 as the route for through traffic. At Flomaton, US31 begins a 15-mile virtual east-west concurrency with US29 that continues to Brewton, North of Brewton, US31 assumes a northeast-southwest trajectory, passing through rural areas and small towns in Escambia and Conecuh Counties. In Evergreen, US31 north and US84 share a concurrency heading north. The two routes do not junction each other again for another 22 miles, US31 is routed along a bypass of Montgomery, the state capital. At Prattville, this route intersects U. S. Route 82, North of Prattville, US31 passes through rural areas of Autauga and Chilton Counties, primarily along two-lane roadways. Between Prattville and Alabaster, US31 has three interchanges with I-65, between Saginaw and Warrior, US31 is routed along multi-laned routes as it passes through the Birmingham-Hoover Metropolitan Area. It passes through such as Alabaster, Pelham, Hoover. In Homewood, US31 merges with U. S. Route 280 and is routed along the Elton B. Stephens Expressway, US31 and 280 are co-routed until the expressway junctions I-20/59 just northeast of downtown. This interchange serves as the terminus of US280. At Warrior, the roadway shrinks to two lanes, two miles north of Warrior, US31 and I-65 begin a three-mile concurrency between the interstate routes Exits 284 and 287. The interstate route was constructed over US 31s roadway through this segment, between the split from I-65 and Garden City, US31 is routed along a narrow two-lane route. North of Garden City, and passing through Cullman, Hartselle, Decatur and Athens, it is routed along multi-lane, at Athens, I-65 and US31 begin a concurrency that continues to just north of the Tennessee state line. In both states, US31 is largely unsigned, given US 31s former importance as a major connecting route in Alabama, in several cities it is known by the name of the city it leads to. For example, south of Montgomery it is still named Mobile Highway, similarly, south of Birmingham it is referred to as Montgomery Highway, and northwardly it is referred to as the Decatur Highway
3.
U.S. Route 72 Alternate
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Alternate US-72 exists in Alabama on the mostly south side of the Tennessee River between Muscle Shoals and Decatur, while US-72 follows on the north side of the river between Florence and Athens. Alternate 72 crosses the Tennessee River at Decatur, Alabama along with U. S. Highway 31, SR-20 was co-signed with Alt US-72 from Muscle Shoals to Huntsville. SR-20 has since been truncated to the junction of I-65 just east of Decatur, originally, Alt US-72 turned off SR-20 on to SR-53 / Jordan Lane in Huntsville and followed it north 1-mile to rejoin with US-72. With the completion of I-565 in the early 1990s, Alt US-72 was routed along with I-565 to the termination of I-565 at US-72. ALT72 enters Decatur, Alabama after leaving Trinity, carrying Alabama 20, and serves as the northern terminus for The Beltline and continues eastward towards the town center
4.
Tennessee River
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The Tennessee River is the largest tributary of the Ohio River. It is approximately 652 miles long and is located in the southeastern United States in the Tennessee Valley. The river was once known as the Cherokee River, among other names, as many of the Cherokee had their territory along its banks, especially in eastern Tennessee. Its current name is derived from the Cherokee village Tanasi, the Tennessee River is formed at the confluence of the Holston and French Broad rivers on the east side of present-day Knoxville, Tennessee. From Knoxville, it flows southwest through East Tennessee toward Chattanooga before crossing into Alabama and it loops through northern Alabama and eventually forms a small part of the states border with Mississippi, before returning to Tennessee. At this point, it defines the boundary between two of Tennessees Grand Divisions, Middle and West Tennessee and this waterway reduces the navigation distance from Tennessee, north Alabama, and northern Mississippi to the Gulf of Mexico by hundreds of miles. The final part of the Tennessees run is in Kentucky, where it separates the Jackson Purchase from the rest of the state and it flows into the Ohio River at Paducah, Kentucky. The river has been dammed numerous times, primarily in the 20th century by Tennessee Valley Authority projects since the 1930s, a navigation canal located at Grand Rivers, Kentucky, links Kentucky Lake and Lake Barkley. The canal allows for a trip for river traffic going from the Tennessee to most of the Ohio River. Maps from the early 18th century call it Cussate, Hogohegee, Callamaco, a 1755 British map showed the Tennessee River as the River of the Cherakees. By the late 18th century, it had come to be called Tennessee, the river was a major highway to transport goods and explorers in the years when Tennessee was not yet settled. Some major towns that still exist today, and major ports at them were established by those who rode down the river, and settled along it. The Tennessee River begins at mile post 652, where the French Broad River meets the Holston River, in the late 18th century, the mouth of the Little Tennessee River was considered to be the beginning of the Tennessee River. Through much of the 19th century, the Tennessee River was considered to start at the mouth of Clinch River, at various points since the early 19th century, Georgia has disputed its northern border with Tennessee. Georgia made several attempts to correct what Georgia felt was an erroneous survey line in the 1890s,1905,1915,1922,1941,1947 and 1971 to resolve the dispute. Crews Townsend, Joseph McCoin, Robert F. Parsley, Alison Martin and Zachary H. Greene, writing for the Tennessee Bar Journal, a publication of the Tennessee Bar Association, appearing on May 12,2008. In 2008, as a result of a drought and resulting water shortage. In a two-page resolution passed overwhelmingly by the senate, Georgia declared that it, not its neighbor to the north
5.
Decatur, Alabama
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Decatur is a city in Morgan and Limestone counties in the State of Alabama. The city, affectionately known as The River City, is located in Northern Alabama on the banks of Wheeler Lake and it is the largest city and county seat of Morgan County. The population in 2010 census was 55,683, Decatur is also the core city of the two-county large Decatur, Alabama Metropolitan Area which had an estimated population of 153,374 in 2013. Combined with the Huntsville Metropolitan Area, the two create the Huntsville-Decatur Combined Statistical Area, of which Decatur is the second largest city and this city is also known as the Dirty D. This town lit OML Like many southern cities in the early 19th century, Railroad routes and boating traffic pushed the city to the front of North Alabamas economic atmosphere. The city rapidly grew into an economic center within the Tennessee Valley and was a hub for travelers. Throughout the 20th century, the city experienced steady growth, but was eclipsed as the economic center by the fast-growing Huntsville during the space race. The city now finds its economy based on manufacturing, cargo transit, and hi-tech industries such as General Electric. The city was incorporated as Decatur in 1821 and it was named in honor of Stephen Decatur, after he was killed in a duel in 1820, President Monroe directed that the Alabama town be named for him. In the early 1830s, Decatur was the terminus of the Tuscumbia, Courtland and Decatur Railroad. In 1850 the Tuscumbia, Courtland and Decatur Railroad was incorporated into the Memphis & Charleston Railroad, because of its location on the Tennessee River at the strategically important crossing of two major railroads, Decatur was the site of several encounters during the American Civil War. When the Union army occupied the city early in the war, bricks from some of the churches in town were used to build stoves and chimneys for the buildings that housed soldiers. The four buildings that remained are the Old State Bank, the Dancy-Polk House, the Todd House, while the city was under Confederate control, plans for the Battle of Shiloh were mapped out within the Burleson-Hinds-McEntire House. These activities make the one of the most historic buildings in Decatur. New Decatur, Alabama was a city that rose out of the ashes of former Decatur west of the railroad tracks, New Decatur was founded in 1887 and incorporated in 1889. However, residents of the older Decatur resented the new town, animosity built until New Decatur renamed their town Albany, after Albany, N. Y. in September 1916. The impetus to meld the two came from the need for a bridge, instead of a ferry, across the Tennessee River. The Decatur Kiwanis Club was formed with an number of members from each town to organize efforts to get the state to build the bridge
6.
Morgan County, Alabama
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Morgan County is a county in the north central part of the U. S. state of Alabama. As of the 2010 census the population was 119,490, the county was created by the Alabama Territorial legislature on February 6,1818 from land acquired from the Cherokee Indians in the Treaty of Turkeytown, and was originally called Cotaco County. On June 14,1821 it was renamed in honor of American Revolutionary War General Daniel Morgan of Virginia and it is a prohibition or dry county, though the city of Decatur is wet. Morgan County is included in the Decatur, AL Metropolitan Statistical Area and it is a part of the North, Northwest, and North-Central regions of Alabama. According to the U. S. Census Bureau, the county has an area of 599 square miles. The population density was 191 people per square mile, there were 47,388 housing units at an average density of 81 per square mile. 3. 28% of the population were Hispanic or Latino of any race,24. 80% of all households were made up of individuals and 9. 40% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the family size was 2.99. In the county, the population was out with 25. 30% under the age of 18,8. 40% from 18 to 24,30. 10% from 25 to 44,23. 80% from 45 to 64. The median age was 37 years, for every 100 females there were 96.20 males. For every 100 females age 18 and over, there were 93.50 males, the median income for a household in the county was $37,803, and the median income for a family was $45,827. Males had an income of $35,759 versus $21,885 for females. The per capita income for the county was $19,223, about 9. 70% of families and 12. 30% of the population were below the poverty line, including 15. 90% of those under age 18 and 12. 80% of those age 65 or over. As of the census of 2010, there were 119,490 people,47,030 households, the population density was 206.4 people per square mile. There were 51,193 housing units at a density of 88 per square mile. The racial makeup of the county was 79. 8% White,11. 9% Black or African American,0. 9% Native American,0. 6% Asian,0. 1% Pacific Islander,4. 8% from other races, and 2. 0% from two or more races. 7. 7% of the population were Hispanic or Latino of any race,25. 9% of all households were made up of individuals and 9. 8% had someone living alone who was 65 years of age or older. The average household size was 2.50 and the family size was 2.99
7.
Limestone County, Alabama
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Limestone County is a county of the U. S. state of Alabama. As of the 2010 census, the population was 82,782. Its name comes from Limestone Creek, a local stream, Limestone County is included in the Huntsville, AL Metropolitan Statistical Area. Limestone County was established by the Alabama Territorial legislature on February 6,1818, on November 27,1821, the Alabama State legislature passed an Act that altered the boundary of Limestone County to include the area east of the mouth of the Elk River with the Tennessee River. At the time, that area was a part of Lauderdale County, according to the U. S. Census Bureau, the county has a total area of 607 square miles, of which 560 square miles is land and 47 square miles is water. It is the third smallest county in Alabama by land area, there were 26,897 housing units at an average density of 18/km2. 2. 65% of the population were Hispanic or Latino of any race,23. 40% of all households were made up of individuals and 8. 90% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the family size was 3.02. In the county, the population was out with 24. 90% under the age of 18,8. 80% from 18 to 24,32. 10% from 25 to 44,23. 10% from 45 to 64. The median age was 36 years, for every 100 females, there were 103.10 males. For every 100 females age 18 and over, there were 101.80 males, the median household income in the county was $37,405, and the median income for a family was $45,146. Males had an income of $35,743 versus $23,389 for females. The per capita income for the county was $17,782, about 9. 80% of families and 12. 30% of the population were below the poverty line, including 16. 20% of those under age 18 and 14. 60% of those age 65 or over. As of the 2010 census, there were 82,782 people,31,446 households, there were 34,977 housing units at an average density of 24. 1/km2. The racial makeup of the county was 80. 3% White,12. 6% Black or African American,0. 7% Native American,1. 1% Asian,0. 1% Pacific Islander,3. 5% from other races, and 1. 8% from two or more races. 5. 5% of the population were Hispanic or Latino of any race,23. 7% of all households were made up of individuals and 8. 5% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the family size was 3.00. In the county, the population was out with 24. 0% under the age of 18,8. 0% from 18 to 24,28. 1% from 25 to 44,27. 6% from 45 to 64
8.
Cantilever bridge
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A cantilever bridge is a bridge built using cantilevers, structures that project horizontally into space, supported on only one end. Engineers in the nineteenth century understood that a bridge that was continuous across multiple supports would distribute the loads among them and this would result in lower stresses in the girder or truss and meant that longer spans could be built. Several nineteenth century engineers patented continuous bridges with hinge points mid-span, the use of a hinge in the multi-span system presented the advantages of a statically determinate system and of a bridge that could handle differential settlement of the foundations. Engineers could more easily calculate the forces and stresses with a hinge in the girder, heinrich Gerber was one of the engineers to obtain a patent for a hinged girder and is recognized as the first to build one. The Hassfurt Bridge over the Main river in Germany with a span of 124 feet was completed in 1867 and is recognized as the first modern cantilever bridge. The High Bridge of Kentucky by C, the Kentucky River Bridge spanned a gorge that was 275 feet deep and took full advantage of the fact that falsework, or temporary support, is not needed for the main span of a cantilever bridge. The most famous early cantilever bridge is the Forth Bridge and this bridge held the record for longest span in the world for seventeen years, until it was surpassed by the Quebec Bridge. Benjamin Baker illustrated the principles of the suspended span cantilever in the photo on the left. The suspended span, where Kaichi Watanabe sits, is seen in the center, the need to resist compression of the lower chord is seen in the use of wooden poles while the tension of the upper chord is shown by the outstretched arms. The action of the foundations as anchors for the cantilever is visible in the placement of the counterweights. A simple cantilever span is formed by two arms extending from opposite sides of an obstacle to be crossed, meeting at the center. In a common variant, the span, the cantilever arms do not meet in the center, instead. The suspended span may be built off-site and lifted into place, thus, in a bridge built on two foundation piers, there are four cantilever arms, two which span the obstacle, and two anchor arms which extend away from the obstacle. Because of the need for strength at the balanced cantilevers supports. The Commodore Barry Bridge is an example of type of cantilever bridge. Steel truss cantilevers support loads by tension of the upper members, commonly, the structure distributes the tension via the anchor arms to the outermost supports, while the compression is carried to the foundations beneath the central towers. Many truss cantilever bridges use pinned joints and are statically determinate with no members carrying mixed loads. Prestressed concrete balanced cantilever bridges are built using segmental construction
US 31 / US 72 Alt. / SR 20
