Civil

Duck Creek Aqueduct is a rare surviving example of a covered timber aqueduct. It was one of several similar structures on the Whitewater Canal, which operated between the Whitewater Valley and the Ohio River from 1839 to 1865. After being displaced by the railroad, the canal supplied hydraulic power for the industrial districts at Metamora and Brookville.

Doe River Bridge is a fine example of a timber Howe truss, one of the most widely-used timber bridge designs. Built in 1884, this structure played an integral role in the development of the City of Elizabethton, Tennessee, and it is a rare example of a covered bridge that survives in an urban setting.

The original contract specified the unusual hip roof design, which resembles covered bridges in central Europe. The structure is very well-maintained and still carries automobile traffic. The bridge was restored in 2003.

Bunker Hill Bridge is the only surviving Haupt truss bridge in the U.S. and one of only two surviving covered bridges in North Carolina. Patented in 1839, the Haupt truss featured diagonal braces spanning multiple panels, which was an attempt to eliminate the cross-strain found in lattice truss bridges. Although it was almost immediately eclipsed by the Howe truss and never reached the mainstream of covered bridge building, the Haupt truss is of interest for its association with Gen.

The Ashuelot Covered Bridge is located at the center of Ashuelot, NH. It is a Town lattice truss bridge, spanning the Ashuelot River in a roughly north-south orientation. It consists of two spans with a total length of 178 feet (54 m). The total width of the bridge is 29 feet (8.8 m), and has a central roadway and sidewalks (measuring 3'10" in width) on each side. The bridge rests on stone abutments and a central pier. The abutments have been reinforced with concrete since the bridge was built, and the central pier has been protected by a metal breakwater.

Ackley Bridge is an excellent example of a multiple kingpost truss and a noteworthy early example of covered bridge preservation efforts in the United States. Built in 1832 by Joshua Ackley (b.1805) and Daniel Clouse (b.1812), Ackley Bridge originally spanned Enslow’s Branch of Wheeling Creek between Greene County and Washington County in Pennsylvania, where it carried traffic for over a century.

Spearheaded by Chief Engineer William J. Wilgus and constructed under challenging conditions with no interruption of existing train service, Grand Central Terminal was a triumph of innovative engineering in the design of urban transportation centers. Its novel, two-level station, made possible by electric traction, streamlined both train and passenger movement by separating long-haul and suburban traffic and employing an extensive system of pedestrian ramps throughout the facility.

"It remains today one of the great bridge engineering accomplishments for railway and highway bridges built in the country." 
 - Historic American Engineering Record, Southeast Regional Office, National Park Service, U.S. Department of the Interior, 2005

In the 1940s and 1950s, New Orleans experienced growth. Unfortunately, access from the north to the City continued to be limited by Lake Pontchartrain. Driving around the Lake was a time consuming effort. During this time period, a renewed interest developed to provide a direct connection across the center of the Lake to the north shore. As a result, the Greater New Orleans Expressway Commission was formed to build the Lake Pontchartrain Causeway Bridge. The original bridge (southbound) was opened on August 30, 1956.

In May 1927, the same month of Charles A. Lindbergh's famous transatlantic flight from New York to Paris, a fact-finding commission appointed by the U.S. Secretary of Commerce concluded that Newark would be the ideal location for an airfield to serve the greater New York/New Jersey metropolitan area.

Civic leaders wasted no time; construction began on the Newark Airport in January 1928. Nine months and $1,750,000 later, 68 acres of soggy marshland had been filled and converted to an airport.

With the dawn of the automobile age at the beginning of the Twentieth Century, the entire nation started to demand better roads. In the 1910s, motorists and businessmen in Utah became aware of the possibilities of tourism as a business. Soon the state of Utah and the federal government responded with a decades-long program to improve transportation to and within Zion National Park.

Several factors argued for a road through Zion National Park: