|Stewart International Airport Access Improvement Project|
The day before Thanksgiving is one of the busiest travel days of the year at airports. However, this past Thanksgiving, air passengers in the Hudson Valley region had an easier time getting to Stewart International Airport in Newburgh, New York because of the recent opening of Exit 5A on Interstate 84 and new access roads leading to the airport. Paul Pasternak, P.E., of DMJM+Harris gave a presentation to the Met Section's Construction Group describing the Stewart International Airport Access Improvement Project on March 13, 2008 at Cooper Union in New York City.
The presentation concluded a two-part lecture that began with a presentation of Electronic Engineering Data (EED) in construction, including Automated Machine Guidance (AMG) and automated stakeout and survey. The construction of the new interchange and access roads leading to Stewart Airport used some of these innovative technologies.
Originally conceived as an airfield for cadets at the nearby United States Military Academy at West Point, Stewart Airport has an interesting history since its opening in 1934. Following World War II, the airfield became an air force base, but the base was shut down in 1970 and later transferred to New York State. With a main runway of nearly 12,000 feet, the airport can accommodate nearly any aircraft in the world and is a designated emergency runway for the Space Shuttle. New York State saw Stewart's potential as a fourth airport for the New York City metropolitan region with the possibility for supersonic air travel and began acquiring additional land adjacent to the airport for a potential expansion. The 1973 oil crisis and other economic factors put a damper on development of the airport, which did not see its first commercial air service begin until 1990. The airport operation was privately leased to National Express in 1999 and was taken over by the Port Authority of New York & New Jersey in November 2007.
Despite being located near Interstate 84 and Interstate 87, getting to Stewart Airport has always been difficult. Motorists previously needed to follow a circuitous path around the airport through congested traffic signals on Route 300 and Route 207 in order to get to the terminal area. Plans for improved access to the airport were advanced in 2000 following the privatization of the airport, but were later stalled by lawsuits against the project's Environmental Impact Statement. As development of the airport slowly progressed through the 1980s and 1990s, local residents began to realize the recreation possibilities offered by the vacant land acquired by New York State for airport expansion and a noise buffer. For this reason, the project had to be developed with minimal impacts to the environment.
Starting in January 2006, the project began converting the existing two-lane Drury Lane into a four-lane divided highway with a new a new interchange connecting it to Interstate 84. An east-west connection was also constructed between Drury Lane and the airport terminal area. Over one million cubic meters of earthwork were required for the project, which involved 3.1 miles of roadway reconstruction and 1.9 miles of new roadway construction. The project included four new bridges, a steel beam bridge over Interstate 84 and three bridges (concrete bulb tee beam and concrete box beam) over the Catskill Aqueduct. The bridge over Interstate 84 was installed during a ten-minute nighttime lift.
The project used automated stakeout and survey using GPS and Lancaster Development Inc. used AMG to control its bulldozers using a computer generated 3D machine model and GPS guidance. GPS uses a constellation of 24 satellites; a minimum of four of which are needed to establish x, y, z, and time coordinates. To provide Real-Time Kinematic (RTK) corrections to the GPS rovers, a base station was established behind the airport's security fence. Because of the site's hilly topography, repeaters were sometimes used to help the GPS units communicate with the base station. To establish the accuracy of field measurements, a series of guidelines were developed to establish the minimum number of satellites required, their position in the horizon, and the relative strength of the GPS satellite configuration.
Steepened side slopes using Mechanically Stabilized Earth Systems (MSES) and Geosynthetic Reinforced Earth System (GRES) walls were included in the project's design to minimize wetland impacts. A total of 13.3 acres of new wetlands were created in the vicinity of the project site to mitigate the project's impact to 6.47 acres of existing wetlands. One large wetland area was entirely constructed using GPS stakeless survey. Additionally, 12 vernal pools were constructed along the roadway corridor, providing a safe habitat for the blue-spotted and Jefferson salamanders that were native to the area, and a "species of special concern" according to the U.S. Department of Environmental Protection. Special 8-meter high underpasses were constructed using precast units to serve as wildlife underpasses and provide access for salamanders without them having to cross the roadway. At these locations, amphibian barriers were created to help direct salamanders into the underpass. Brush piles were created to provide improved habitats for rabbits. Tree removal was limited to the period of November-March to avoid impacting the Indiana Bat, an endangered species that roosts in the area. Additionally, wetland mitigation areas were located to avoid purple milkweed, a rare species in the eastern portion of the United States. As a result of these environmental improvements, the project earned an Exemplary Ecosystem Initiative award from the Federal Highway Administration.
The ribbon cutting ceremony was held on November 21, 2007, when the east-west connecting road between Drury Lane and the airport terminal was opened to the public. Drury Lane, which now provides access to the airport, was fittingly designated by the New York State Department of Transportation as Route 747.
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