Aircraft bridge

Aircraft bridges, including taxiway bridges and runway bridges, bring aircraft traffic over motorways, railways, and waterways, and must be designed to support the heaviest aircraft that may cross them. In 1963, a taxiway bridge at Chicago O'Hare Airport, one of the busiest airports in the world, was planned to handle future aircraft weighing 365,000 pounds (166,000 kg), but aircraft weights doubled within two years of its construction.[1] Currently the Airbus 380 is the world's largest airplane in operation, with maximum take-off weight (MTOW) of 575 t (1,268,000 lb). The largest Boeing planes, i.e. the current "Project Ozark" versions of the Boeing 747-8, are approaching MTOW of greater than 1,000,000 lb (450,000 kg). Aircraft bridges must be designed for the substantial forces exerted by aircraft braking, affecting the lateral load in substructure design.[2] Braking force of 70 percent of the live load is assumed in two recent taxiway bridge designs.[2][3] And "deck design is more apt to be controlled by punching shear than flexure due to the heavy wheel loads."[2]

Taxiway bridges are unusually wide relative to their length, and aircraft loading cannot be assumed to be distributed evenly to a bridge superstructure's web, so different modeling is required in these bridges' structural design.[4]:2–3 In cold climates, provisions for anti-icing must be made. In the U.S., regulations of the Federal Aviation Administration must be met.[2][5] And there are various other differences versus typical bridges covered by AASHTO standards.[6]

A major issue is that closing an airport for construction even temporarily is impossible.

Major alternatives considered for construction of a taxiway bridge in 2008 were:

Finite Element Analysis has been advocated for, or applied in, taxiway bridge design since at least 1963.[7]

Example: Port Columbus Airport Crossover Taxiway Bridge

The Port Columbus Airport Crossover Taxiway Bridge is an aircraft taxiway bridge at Port Columbus International Airport in Columbus, Ohio that was completed in 2008. It is a 24-cell box-girder bridge that spans the primary entrance roadway to the airport terminal. The taxiway bridge would allow aircraft to travel from the main terminal building to new outer runways of the airport. The bridge has a single 191 feet (58 m) span, is 217 feet (66 m) wide and is designed to carry a 747-400 aircraft weighing 894,900 pounds (405,900 kg).[4]:2 In order to fulfill the load requirements of large aircraft, the bridge design employs a post-tensioned cast-in-place concrete structural system with integral abutments. To keep the deck free from ice in winter a hydronic anti-icing system consisting of tubes containing glycol from a pump and heater is embedded into the deck.[4]:3

Structural design of the box-girder bridge was guided by two applications of finite modeling. One modeled the cross-section of the concrete box of the bridge and allowed for aircraft to be placed variously. This yielded implications for the transverse reinforcement and post-tensioning in the top slab of the concrete box. A second model yielded implications for the superstructure's flexural strength requirements, for connections to the integral abutments, for the two huge abutment walls, and for drilled shafts. The abutment walls are each 230 feet (70 m) long, 30 feet (9.1 m) tall, and from 7.5 feet (2.3 m) to 6 feet (1.8 m) thick.[4]:2–3

Lighting requirements specified by the Ohio Department of Transportation are met, and then for aesthetics alone, a system of blue linear lights are integrated into the underside of the bridge and inclined abutments.[4]:4

The entrance roadway spanned by the bridge, named the International Gateway, is a below-grade roadway with seven vehicle lanes and two light rail lines. Also crossing the International Gateway are two other single-span post-tensioned bridges. These provide for maintenance and other vehicular traffic around the perimeter of the airport and 74 feet (23 m) and 29.5 feet (9.0 m) wide.[4]:1

Design and construction

The bridge was completed in 2008. Architect Miguel Rosales of Boston-based transportation architects Rosales + Partners provided the conceptual design, visualizations and final design.[4] The Engineer of Record was R.W. Armstrong. The construction team included contractor C.J. Mahan Construction Company, and concrete suppliers Arrow Concrete (drilled shafts) and Anderson Concrete (superstructure and abutments).[4]

Construction time and cost was saved by a choice of the contractor. Instead of excavating and then building falsework before casting the superstructure of the bridge, the contractor chose to build it supported by the ground, and then excavate underneath. This was feasible as the initial ground level was approximately at the level required for the bottom of the planned superstructure.[4]:3

The bridge received the 2008 Portland Cement Association Bridge Award.[4]

List of taxiway bridges, runway bridges, and related tunnels

Kai Tak Tunnel east entrance, near the old Kai Tak airport

Taxiway bridges and runway bridges are bridges at airports to bring airplane taxiways and runways across motorways, railroads, or waterways. A taxiway bridge must be designed to carry the weight of the maximum size airplanes crossing and perhaps stopping directly upon it. A runway bridge is similar but may have different stresses. Alternatively, a motorway may be brought by tunnel underneath one or more runways and taxiways. Examples include:

Numerous taxiway bridges have been proposed but not built.

References

  1. 1 2 O.C. Guedelhoefer and J.R. Janney. W.R. Schriever, ed. Evaluation of Performance by Full-Scale Testing. American Society for Testing and Materials. pp. 17–19. (book title is Full-Scale Load Testing of Structures)
  2. 1 2 3 4 5 6 Ted Bush, Kent Bormann, and Rob Turton (Spring 2008). "Airport Bridges Take Off" (PDF). Aspire. Retrieved July 31, 2016.
  3. 1 2 Shane Johnson and Tom Morrison (April 10, 2015). "Design and Construction of Micropiles Supporting Taxiway Bridge" (PDF).
  4. 1 2 3 4 5 6 7 8 9 10 11 Kevin M. Gorak and Troy D. Jessop (Winter 2009). "A New Welcome at the Port Columbus International Airport" (PDF). Aspire: 34–37. Retrieved 17 May 2013. (with 4 pages of additional photos published in the web version)
  5. ↑ "Advisory Circular AC 150/5300-13A" (PDF). Federal Aviation Administration. May 1, 2012.
  6. ↑ Anthony N. Mavrogiannis, of Airport Consultants Council, Review Comments on Advisory Circular 150/5300-13, Airport Design, see esp. p.3.
  7. ↑ Alan R. Jefts (1983). Finite Element Analysis of a Taxiway Bridge. American Society of Civil Engineers. in book Proceedings of the Eighth Conference on Electronic Computation
  8. ↑ LAX airport diagram, 1956 shows runways 25 and 26 crossing the line of Sepulveda Boulevard (although boulevard is not indicated).
  9. ↑ David A. Burrows (October 2013). "Bridges for Planes, Trains, but not Automobiles". Structure.
  10. ↑ "Tampa International Airport - Taxiway B Bridge Design-Build. Tampa, Florida". Finley Engineering Group.
  11. ↑ Sun Rongmei and Zhang Xianmin. "Dynamic Analysis of the Taxiway Bridge Under Aircraft Moving Load".
  12. ↑ Corrosion Investigation Study of Reinforcing Steel Taxiway Bridge and Spiral Ramps at Chicago-O'Hare International Airport. 1982.
  13. ↑ Airport World 1973, vol 6, pages 36-37.
  14. 1 2 3 4 Google maps, accessed July 2016
  15. ↑ Anthony Walker. Hong Kong: The Contractors' Experience. p. 89.

External links

Coordinates: 40°00′01″N 82°54′19″W / 40.0002°N 82.9052°W / 40.0002; -82.9052

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