airport engineering[′er‚pȯrt en·jə′nir·iŋ]
A terminal facility used for aircraft takeoff and landing, and including facilities for handling passengers and cargo and for servicing aircraft. Facilities at airports are generally described as either airside, which commences at the secured boundary between terminal and apron and extends to the runway and to facilities beyond, such as navigational or remote air-traffic-control emplacements; or landside, which includes the terminal, cargo-processing, and land-vehicle approach facilities.
Airport design provides for convenient passenger access, efficient aircraft operations, and conveyance of cargo and support materials. Airports provide facilities for changing transportation modes, such as people transferring from cars and buses to aircraft, cargo transferring from shipping containers to trucks, or regional aircraft supplying passengers and cargo for intercontinental aircraft. In the United States, engineers utilize standards from the Federal Aviation Administration (FAA), aircraft performance characteristics, cost benefit analysis, and established building codes to prepare detailed layouts of the essential airport elements: airport site boundaries, runway layout, terminal-building configuration, support-building locations, roadway and rail access, and supporting utility layouts. Airport engineers constantly evaluate new mechanical and computer technologies that might increase throughput of baggage, cargo, and passengers.
Site selection factors vary somewhat according to whether (1) an entirely new airport is being constructed or (2) an existing facility is being expanded. Few metropolitan areas have large areas of relatively undeveloped acreage within reasonable proximity to the population center to permit development of new airports. For those airports requiring major additional airfield capacity, however, and hence an entirely new site, the following factors must be evaluated for each alternate site: proximity to existing highways and major utilities; demolition requirements; contamination of air, land, and water; air-traffic constraints such as nearby smaller airport facilities; nearby mountains; numbers of households affected by relocation and noise; political jurisdiction; potential lost mineral or agricultural production; and costs associated with all these factors. Some governments have elected to create sites for new airports using ocean fills. The exact configuration of the artifical island sites is critical due to the high foundation costs, both for the airport proper and for the required connecting roadway and rail bridges.
Since the runways and taxiways constitute the largest portion of the airport's land mass, their layout, based on long-term forecasts of numbers of aircraft landings and departures, is generally one of the first steps in the airport design. A paved runway surface 12,000 ft (3660 m) long and 150 ft (45 m) wide is suitable for most applications. Runway length requirements change according to the type of aircraft, temperature, altitude, and humidity encountered. A parallel taxiway is generally constructed 600 ft (180 m) from the runway (measured centerline to centerline). It is connected by shorter high-speed taxiways to allow arriving aircraft to leave the runway surface quickly in order to clear another aircraft arrival as quickly as possible. This combination is generally referred to as a runway-taxiway complex.
Ideally, airports can exclusively utilize parallel runway complexes so that incoming and departing aircraft can also be parallel for safe, simultaneous operations. Under these conditions, runway thresholds would be slightly staggered to avoid wake turbulence interference between incoming aircraft. Staggered thresholds might also be used to minimize crossing of active runways by taxiing aircraft. Each crossing is a potential aircraft delay and a safety hazard.
When airports have sufficiently high-velocity crosswinds or tailwinds from more than one direction, crosswind runways must also be provided. These crosswind runways are located at some angle to the primary runway as dictated by a wind rose analysis.
Runways are paved with concrete, asphalt, concrete-treated base, or some combination of layers of these materials. Runways for larger aircraft require thicker, more expensive pavement sections. Engineers design these pavements for long design lives. The expected life of a concrete runway can be increased from 20 to 40 years, based on enhanced mix designs and sections. See Concrete, Pavement
A system of vehicle service roads must be provided around the perimeter of the airfield both for access to the runways and for security patrols of the perimeter fencing. Airfield security fencing with a series of access gates is monitored with patrols and, increasingly, a remote camera surveillance system.
The terminal is generally the airport building that houses ticketing, baggage claim, and transfer to ground transportation. The concourse is generally the combination of facilities for boarding aircraft, sorting baggage according to flight, and unloading cargo carried in commercial aircraft. Airport terminal and concourse configurations generally fall into three categories: (1) terminal contiguous with concourse satellite extensions (known as piers or fingers) used for boarding aircraft; (2) unit terminals, which serve as transfer points both from ground transportation modes into the building and from the building into the aircraft; (3) and detached terminal and concourses, sometimes referred to as a landside and airside terminals, connected by a people-mover train system, an underground walkway or a surface transport vehicle.
The primary types of support buildings required by the airlines for their airport operations are flight kitchens to prepare meals for passengers, hangars to service aircraft, and ground support equipment buildings to service ground support vehicles such as tugs, baggage carts, and service trucks. The high number of trips for support vehicles to travel from these buildings to load or service aircraft requires that the buildings be located in reasonable proximity to the aircraft gates. However, the buildings should be sufficiently far to allow the concourses to be expanded without requiring demolition of these support facilities.
An airport requires fire equipment to provide extremely fast primary and secondary response to each and every runway. Locating the aircraft rescue and fire-fighting stations requires careful positioning with respect to the taxiway system. Other types of support buildings include storage buildings, employee facilities, administrative offices, vehicle maintenance buildings for snow removal and airport vehicles, roadway revenue plaza offices, and training facilities.
Fuel and deicing facilities
Economies of scale and safety considerations generally encourage the implementation of large, centralized common systems for aircraft fuel. The large storage tanks required to ensure adequate reserves of fuel are located in remote areas of the airport, generally in aboveground facilities. Underground distribution piping then transports the fuel to hydrant pits or truck fueling stations close to aircraft operations. This system, like most utilities, is designed with backup capacity by looping piping around each service area. If a break occurs in a section of pipe, valves are automatically closed and the supply direction is reversed. Fuel tanks require extensive analysis of structural, mechanical, and electrical design. These tanks are widely spaced to avoid the transmission of fire and to allow room for a surface detention area to store burning fuel.