When designing airports, amenities, cost-effective structures, aircraft safety, and operations and profitability are all key considerations for airport planners, operators and their stakeholders, and the engineers and architects designing the solutions.
Design challenges occur both airside and landside. Many are interrelated and, in all scenarios, can negatively impact an airport’s operations and profitability if not thoroughly considered and addressed.
Challenge #1: Mitigating noise impact of airside and landside activities on airport operations, profitability and beyond the runway.
Airports are very noisy places. Although today’s commercial aircraft emit 70 per cent less noise than those built 40 years ago[i], airside activities such as aircraft landing and taking off as well as other apron activities including aircraft taxiing, refuelling, maintenance and baggage loading/unloading mean that noise and vibration remain primary causes of objections to airports around the world.
As a consequence, extreme difficulty can be encountered when looking to build new airports, expand existing airports and schedule aircraft movements, especially at night.
Combined, the noise emissions generated from such activities have a significant impact on an airport’s operational hours and, in turn, its profitability.
Generally speaking, noise mitigation measures can be categorised into the following four categories:
- Land use controls/compatibility
- Operational changes in the use of the airport, aircraft or airspace
- Physical modifications to the airport
- Noise management and wider community processes
Land use planning is critical to noise management and mitigation. Normally the responsibility of local governments, airport operators work with local authorities to develop zoning and land use rules.
Every airport site is different with each subject to a broad and varied range of zoning and land use rules that are enforced to prevent or mitigate noise – sensitive activities in the areas surrounding the airports.
In some cases, including the 24-hour operational Melbourne International Airport, Hobart and Canberra Airports, the well positioned location of the airport site allows for less constrained noise management plans. In other cases, including Perth and Adelaide International Airports, relative proximity to residential areas means airport operators and planners must take a very different approach to controlling noise emissions.
A balanced, integrated approach for addressing aircraft noise at airports, land use planning, noise abatement mechanisms and procedures, and appropriate operating restrictions, is needed to ensure airport and airline operators can maximise airside and landside operational and profit potential.
Involving building sciences in the concept stage of airport planning is critical to designing and constructing an airport hub capable of operating as many hours as possible each day.
Operating costs can be minimised by maximising the operating hours of the airport. Noise emissions are a key to this, with apron activities in the early hours of the morning an important issue.
Ground run-up of aircraft is often carried out using Auxiliary Power Units (APUs) within the tail of the aircraft. These noisy jet engines used to provide power and cabin conditions to aircraft while on the ground can easily exceed noise emission limits depending on the location and orientation of the aircraft relative to the boundary.
However, noise emissions can be significantly reduced by combining ground noise limits and regulations set by airport operators with airside physical modifications, including Fixed Electrical Ground Power, Ground Power Units and Pre Conditioned Air mechanisms.
These procedures significantly reduce the need to use APU by maximising and optimising the use of other services available, resulting in a reduction in ground noise and allowing for maximum operational hours. It is crucial to ensure airline ground noise compliance is monitored as comprehensively as possible. Frequent monitoring and audits of ground noise at various times and locations is essential to obtaining a comprehensive and accurate picture of noise emissions as possible.
Heathrow International Airport is a strong example of how a balanced approach to noise management can maximise operational hours for airports in relative proximity to residential areas. The airport’s proximity to residential areas is an ongoing major challenge for its operators and planners, who must balance increasing commercial aircraft activity and potential airline and passenger revenue with environmental, including noise management, requirements and legislation.
The operators, Heathrow Airport Limited, balance a combination of aircraft and airside operational regulations, physical modifications and stringent noise monitoring audits that are carried out every week, each of which are conducted at different times and locations to effectively manage noise emissions and keep the airport operational 24 hours a day.
Challenge #2: Mitigating the impact of wind load on cost – effective airport structures and ensuring aircraft safety
Terminals are often constructed using portal frames with cantilevers with interfacing long-span curtain walls. Wind loads on such structures can be significant, and the vibration response of cantilevers due to vortex shedding similarly sizeable.
The cost of these structures can be reduced through in-house wind tunnel testing with simultaneous pressure measurements across the structure used to accurately determine equivalent static wind loads, using influence coefficients.
By modelling the dynamics of the structure, vibrations due to vortex shedding can be determined and the structure modified to accommodate or damp the deflections due to wind effects.
Terminals themselves impart turbulence or wind shear onto the runway, which can be hazardous to flight arrivals and departures. This can be assessed early in the planning and design process through measurements of turbulence intensity in the wake of the terminal.
Adding to design challenges, the long span structures commonly used to form arrival and departure halls are susceptible to vibration from baggage handling machines that are usually mounted immediately below public floors, as well as travelators, and footfall from people themselves. The result can be significant discomfort to airport workers and passengers alike.
The key is to utilise finite element methods to model the floor structure and simulate dynamic loads due to machinery or people to understand the response of the structure. The stiffness/mass of the structure can then be modified, or isolation applied to rotating machinery to ensure vibration of the structure is acceptable.
A proper approach taken through the use of wind engineering and structural dynamics capability has the potential to save in the order of 10 per cent of the primary cost of the structure.
Challenge #3: Meeting amenity needs and keeping passengers moving and in the know
Major airport hubs are big, expansive spaces. Moving from check-in to security areas, retail spaces through to airport lounges, gates and baggage claim areas can be an unfamiliar experience for many passengers. Keeping people moving and aircraft arriving and departing on time relies on regular and reliable communication between airline operators and their customers.
Speech intelligibility in airport terminals is paramount to operations. Put simply, an airport will not work without a clear public address system capable of delivering clear communications about flight times and delays; airport gates and baggage claim details, and in some cases, emergencies.
Achieving a high standard of speech intelligibility is challenged by the design of finishes within any airport terminals. Given the volume of people moving through a terminal, durable, hard finishes are required on heavily trafficked areas. These finishes reflect sound, creating a reverberant space, and making it difficult to make public announcements. Absorption to control reflected sound is limited to ceiling or upper level acoustic panels.
Computer modelling utilising ray tracing (modelling the path of reflected sound rays) allows for the optimisation of the type and disposition of acoustic absorption and loudspeakers. Through auralisation, airport operators can have the ability to listen to the announcements as though they were in the terminal.
A design issue not unique to airport design, Aurecon resolved this challenge for the recently completed Queen Elizabeth II Courts of Law in Brisbane, Australia, with in-floor, durable loud speakers that generate local sound to avoid excitation of the reverberant space.
Challenge #4: Keeping passengers comfortable within the airport terminal
Commercially competitive airport hubs are designed for both profit and ever-changing passenger behaviours.
Take airline lounges for example. They provide a private, comfortable space for many frequent flyers in often lengthy transits. Members expect an exclusive area removed from the hustle and bustle of a busy airport terminal. For example, Hong Kong International Airport has airline lounges located on a mezzanine level with indirect exposure to public areas.
Detailed acoustic modelling and auralisation can be used to simulate noise from public areas and to optimise balustrade heights to achieve an acceptable level of intrusive noise within the lounge. Sound masking can also be introduced to further improve the level of amenity within the lounge.
To meet passenger needs, airports are increasingly integrating accommodation, entertainment and leisure facilities into terminals, such as South Korea’s Incheon Airport or Singapore’s Changi Airport, which often have high levels of acoustic amenity required, making their design challenging given the external airport environment.
By: Dr Neil Mackenzie, Aurecon’s Acoustics &Vibrations Leader
[i] Melbourne Airport Master Plan Fact Sheet, Melbourne Airport, November 2012:3