Airports are often the first and the last impression you will get of a city or even a country. It is therefore vital that the impression is a positive one. Although the airport environment is much larger than a terminal building, often the whole airport experience for a passenger hinges on their experience in the terminal.
From a macro perspective, one way to delineate the airport environment is by areas/facilities:
- Landside: On-airport access roads, parking structures/lots, car-rental facilities, public transportation etc.
- Terminal: All the passenger terminals that process passengers for departure and arrival.
- Airfield: All the areas where aircraft operate when on the ground, runways, taxiways, aprons etc.
- Cargo facilities: facilities to handle cargo operations.
- General Aviation: Private aircraft aprons, hangars and Fixed Base Operators (FBO, in essence a private air terminal).
- Support facilities: can include aircraft maintenance, fuel farms, ground service equipment, airport firefighting, police and maintenance.
- Airspace: Everything above the buildings and ground.
We’re going to focus on the terminal aspect of the airport in this article.
Terminal Configurations
Terminals come in all shapes and sizes, some shapes so bizarre they defy definition. From a Terminal Planners’ perspective an airport can be broadly divided into three main areas:
- Airside: Broadly considered to be the airfield where aircraft operate, runways, taxiways aprons and contiguous restricted areas including buildings.
- Landside: Comprises mostly the publicly accessible areas of the airport, consists mainly of transportation and parking.
- Terminal: The bridge between landside and airside, the terminal is split between pre- and post- security.
Terminals in general are divided into two main parts: the processor and the concourse(s). The processor is where the passenger enters and exits the terminal from/to the landside, it’s where a passenger will check-in, go through security and customs as well as retrieve luggage. The concourse is where the passenger will find holdrooms to wait in until the flight is ready to board at the gate (also in the concourse). Functions such as concessions (food & beverage, duty free, etc…), lounges etc can be found in either the processor and/or the concourse depending on the design.
How the processor and concourses are arranged fall into four broad categories (or a combination).
Linear:
The linear configuration is possibly the classic and the simplest of designs, often found in small and medium sized airports, it is easy to navigate and operate up to a certain size. The processor is linked to the concourse along the side opposite the vehicle curb and aircraft are parked head-in perpendicular to the concourse. A terminal with a linear configuration can be expanded by lengthening the concourse or processor on either side. A variant of the linear concourse is the double loaded linear concourse where aircraft are parked on both sides of the concourse.
Pier:
The pier configuration, similar to the linear configuration can be found usually in medium to large sized airports. Usually an airport will have more than one pier to handle aircraft. The concourse is arranged usually perpendicular to the processor with aircraft parked on either side of the pier (and around the space permitting). Piers are usually arranged either parallel to one another or spreading out like a fan from the processor, narrowing as they approach the processor or the processor connector.
Satellite:
A satellite is a concourse that is disconnected from the processor, passengers are processed in the processor and take an underground walkway/automated people mover (APM), busses or skybridge to a concourse before boarding their flight (in reverse for arriving passengers). Modern day satellite concourses are usually built as an expansion to an existing terminal complex to increase capacity.
Remote:
A remote configuration consists primarily of a processor and no real concourse. Passengers are held in a centralized holdroom and are called to a common gate when their flight is ready to board. Passengers are then shuttled to their aircraft via a bus. Essentially, the terminal is a fancy bus station (sometimes not so fancy).
As airports grow in size, their configuration will change as facilities are expanded and new ones added. An airport can have terminals that combine all of these different configurations. Newer airports, usually built on a greenfield site operate at a high capacity from day one with built in capacity to grow in the future (in the US, Denver is one such example).
Levels
When designing a terminal facility, the number of levels a terminal will largely determine the cost of construction as well the possibility of future expansion. Small domestic airports can be a single level facility whereas large airports will usually have departures and the concourse on the upper level with arrivals containing customs and baggage claim on a lower level.
Many smaller regional or domestic airports have all terminal functions located on one floor, the simplicity of a single level terminal has numerous cost benefits from a construction and operations perspective. The downside can be difficulty expanding the facility if demand grows significantly.
In practice, airports that ground load passengers with airstairs or ADA compliant passenger ramps are single level (ie. Long Beach Airport, Burbank Airport or Phoenix Mesa Gateway) without a second level concourse, this type of arrangement is the lowest cost solution. Ground loading works well and is generally appreciated by passengers as long as the terminal is located in a year-round pleasant climate environment. More hostile climatic environments can degrade the passenger experience.
At a most basic level we can also categorize terminals on whether they have a single level roadway or dual level roadway split between departures and arrivals. Airports with single level roadways can have either a single level for passenger traffic (additional smaller levels for administration and other functions can be added) or a dual level with check in and bag claim on the ground level and then second level concourse for the gates and holdrooms.
A major reason to have a second level concourse is the ability to use passenger boarding bridges (PBB). Due to the door height of an aircraft, PBBs usually start from a certain height above the ground and extend and rotate appropriately to form a bridge between the terminal and an aircraft. Due to design and regulatory (Americans with Disabilities Act) requirements it is easier to have the PBB connection point be located on a second level; though ground level PBBs do exist, they are rare and limited in their capabilities.
Large airports hub airports will almost all have multiple levels for passengers and a dual level roadway. Past a certain demand point, it becomes easier and more efficient to handle departures and arrivals on different levels. For passenger flows it makes it easier for wayfinding, the same is also true on the vehicle curbs. Traffic is more easily managed if the vehicle flows are separated.
Why departures on top and arrivals below?
The main driver for arrivals to be on the ground floor has to do with baggage handling systems, they are big, heavy and cumbersome, especially the bag claim devices. It is easier for those systems to be installed on the ground floor for installation as well as maintenance if large components need to be replaced. Additionally, the upper level will not need to be reinforced for the additional weight of the claim devices.
From a passenger perspective; departing passengers are requested by an airline to often be at airport hours ahead of their departure. They will therefore stay longer at the airport than arriving passengers who tend to stay the least amount of time in the airport (unless you are an airport planner and you stick around for some sick reason). The upper level has more architectural opportunities to make a longer stay at the airport more pleasant including higher ceilings, natural light and better airfield views.
Dwell time (time a vehicle is stopped) for vehicles picking up passengers is on average higher than that for vehicles dropping off departing passengers. These longer dwell times translates into higher curbside requirements (longer curbs or more lanes or both). It is easier and cheaper to add lanes at ground level than elevated lanes.
Birth of a Terminal:
Traditionally, airports in the United States are encouraged by the FAA to have a Master Plan. A Master Plan is usually a multi-year effort that in essence charts the course for the entire airport development over a period of time, usually up to fifteen to twenty years, usually in five year increments. Within the last two decades, more and more terminal development projects have proceeded without a Master Plan. The planning phases for a new Terminal follow the same master planning process, only focused narrowly on the Terminal.
A Master Plan or Terminal Development Plan will first inventory the existing terminal facilities and determine how many aircraft, passengers, vehicles can use the terminal. A forecast will then be drawn up to determine aircraft, passenger, cargo and vehicular activity over the span of the planning horizon. An analysis will help determine the difference between what will be needed to meet future passenger demand and what the existing terminal, aprons, taxiways and runways can handle.
Once those facility requirements are drafted, planners will put together different alternatives: different terminal configurations and permutations. Each one of these alternatives will be ranked according to criteria agreed to by the major airport stakeholders. One alternative will triumph over the rest and be selected as the preferred alternative.
The preferred alternative will then proceed from a planning stage to a design stage, where architects design the terminal facility. The chosen design will then be most likely value engineered to reduce costs then moved on to the construction phase. During construction, it is not uncommon for changes to the design (change orders) to occur, most often increasing costs.
The Plan can also set different dates for different facility requirements, meaning that for example 5 years from now we will need a new Terminal to handle 4 million new passengers, fifteen years from now that terminal should be expanded to handle eight million and so on.
The constant saying when designing a terminal (though that may change with potential pandemic mitigation design) is that “you don’t build a terminal for Easter Sunday”. Simply put you don’t design a terminal to the capacity requirements of the peak day of travel, which in the United States is usually Wednesday before Thanksgiving or Sunday after. The idea is to build a Terminal that can handle traffic while providing passengers with a good experience during the peak day of the peak month (in the United States this is often a day in July). This is why a Terminal is packed and many times unpleasant on Thanksgiving or Christmas. If the Terminal was built to the same standards to meet passenger demand for these holiday periods, a large part of the terminal would be underutilized most of the year creating costs for the airport and airlines and ultimately the passenger.
One way that passenger experience can be measured is using a metric called “Level of Service”, this metric was introduced by the International Air Transport Association (IATA) in its Airport Design and Reference Manual (ADRM), though sometimes largely subjective at times. This metric helps airport operators, airlines and planners track how terminal facilities are doing over a period of time and help determine when and where improvements need to be made.
Forces
When deciding to renovate or build terminal facilities, it is important to list all the constraints and opportunities as well as stakeholders, their concerns and issues so as to fully understand the forces at play. Involving stakeholders in decisions and getting their buy-in from day one is essential to achieving a positive outcome resulting in terminal development.
The simplified chart below can show which forces are at play that pull or push terminal development, if a terminal project is decided on some forces will want to pull the size of terminal to be small or even canceled, others will push it to be bigger.
Living Building: Expandability/Scalability
Terminals are functional buildings, but in a way a living one too. Most buildings built outside of an airport retain that footprint and architecture until the end of its useful life. The vast majority of terminals will have different lives, be different buildings. What may seem at first glance to be one building, may in fact be a combination of multiple buildings combined together over decades. Large airports are expected to be operational almost 24/7, it would be very difficult to close a terminal and rebuild a new one in the same place as you would lose the capacity of that terminal during its demolition and the construction of its replacement, the easiest solution is to graft on another section. While in short and medium term this solution does function, the result sometimes is a terminal that seems disjointed for passengers, creating wayfinding issue, reduced levels of service and differing maintenance procedures and life cycles in different parts of the building. One solution to “full-throttle” terminal replacement is to build another “empty chair” terminal that will serve to replace the capacity of a terminal during its demolition and reconstruction. Often this can be done by building a terminal that meets future capacity requirements ahead of schedule, in essence transferring the existing demand requirements to a new facility while the rebuilt facility will meet the future requirements when it reopens.
Newer facilities usually include opportunities for expansion built into the design. This can include leaving undeveloped areas or easily re-devlopable areas adjacent to a terminal that could be used for terminal expansion in the future. A processor can grow along the curb line and the some concourses can be extended to add gates. The midfield satellite concourse option is often chosen for terminal capacity expansion as its construction has minimal impact to existing facilities and space permitting another parallel concourse can be added. This concept was the design for Denver from day one and LAX is opening its first satellite concourse since the sixties in late 2020 (if you look at an aerial image of LAX you can see the original satellites embedded in the concourses in Terminals, 3 ,4 ,5 ,6 and 7, look for the ovals). Zurich Klotten used the new Terminal E Midfield Dock (Midfield Satellite) as an empty chair when it closed and completely rebuilt Pier B.
