Aerobridge – A Revolutionary Architect

History Of The Aerobridge

In 20^th Century, when Wilbur Wright built his first glider where he climbed into his seat in the glider. With the passage of time, small aircraft were developed in which boarding was done via stairs which were part of the aircraft door. This was possible due to the fact that aircraft’s were generally low in height, thus enabling the stairs to be fitted on the door. This method of boarding is still used today in small regional aircraft. The larger aircraft required a different method of loading. External stairs are connected from the aircraft door to the ground. This method can be used virtually on all commercial passenger and cargo aircraft. Initially, these stairs were manually moved by ground staff. It was easy to move these fixed units by ground staff when serving small aircrafts. However, problems cropped up when serving larger aircraft and at larger airports. For serving larger aircraft, manually moving stairs measuring up to 5 meters height would be bigger problems. Also, at large busy airports, it would be virtually impossible to move these stair units around the airport manually. This problem was solved by building the stairs above a truck which would drive the stairs to the aircraft. This allowed transportation of large stairs and also moving it at a quicker speed.

Reason For Introducing The Aerobridge

The main reason for introducing the aerobridge is for passenger comfort. However, it was only possible with the advancement in technology in the 1970s when manufacturers were able meet the mechanical requirements for the operation of the aerobridge.

Considering the social side for introducing the aerobridge, one of the main reasons was to serve disabled passengers without great difficulties. Their immobility may prevent them from using the stairs, thus creating a problem as they may need crews to carry them onto the aircraft and will also likely to slow the boarding process. If the boarding process took longer than expected, the flight may miss their time slot for take-off and clearance thus causing delays.

Another problem the aerobridge solved was sheltering passenger from the weather. At stormy, rainy weathers, passengers are likely to get wet while walking to the stairs. Even once on the stairs which provides an overhead covering, they may get wet due to the uncovered sides. The aerobridge provided a shelter for passengers as the aerobridge is in the form of a tunnel where it shields the weather from the passengers inside. This method of boarding and disembarking have saved a considerable amount of time which is to the advantage of the airline as the turnaround time for the aircraft is shorter thus allowing the airline to maximize the usage of each aircraft.

Since the introduction of the first aerobridge, there have been several improvements made to aerobridges. One of the earliest types is made of aluminium. Although it is light in weight but aluminium would limit its strength considerably. The problem arises when using aluminium since it burns easily and quickly thus it would not meet the safety requirements.

The improved type of an aerobridge manufactured and used nowadays is made out of mild construction steel which is corrugated (Apron Dive Bridge). This provides extra strength and with its coating of fire resistant paint, it can withstand fire for up to 45 minutes which meets the fire safety standard (NFPA-417). The newest type of material used on aerobridge is glass as its side panels. This uses the construction of trusses to support the bridge and is also preferred as glass will not corrode.

The earlier types of aerobridges had fixed supports at both ends which limited its movements thus restricting the number of different types of aircraft the bridge may serve. As design improved over the period of time, aerobridges were constructed with a pivot support at the end closest to the terminal and a roller support at the end closest to the aircraft which allowed the aerobridge to serve a wider range of aircraft. The roller support is created by installing wheels on the end closest to the aircraft which maybe driven, for changing the position of the aerobridge.

Supports Used On The Aerobridges

There are two major types of aerobridges. One uses fixed supports at both ends of the bridge (Pedestal Bridge) while the other type has a pivot support at the end closest to the terminal and a roller support at the end closest to the aircraft. (Apron Drive Bridge)

The Pedestal bridge has fixed supports at both the terminal end and at the aircraft end and may only serve a limited range of aircraft as different types of aircraft have different door height in relations to the ground and the slope should not be greater than 8.33% for passenger comfort. The fixed support also requires the aircraft to be stopped at a near exact position to the cab. The Pedestal Bridge is suitable and useful at terminals which serve a large number of same types of aircraft. Using the pedestal bridges is also advantageous as there is less number of serviceable parts in the pedestal bridge comparing to the apron drive bridge thus minimizing the chance of failure. This is attractive to airport operators as reliability is very important because failures causing the gate to be out of use will lead to delays and inconvenience of passengers.

However, when a range of aircraft is to use the same gate, the Apron Drive Passenger Boarding Bridge (PBB) is more suitable as it may serve a large variety of aircraft since it is capable to move into a range of position. The PBB has a pivot support at the terminal end and a roller support at the aircraft end. This allows the PBB to swing a total of 175degrees (87degrees both clockwise and counterclockwise) and also have the ability to extend out at greater length allowing serving a wide range of aircraft. As noted above, any aerobridge may not generate a slope greater than 8.33% as it may create problems for passengers boarding the aircraft. Therefore, for the PBB to serve in the same gate both large aircraft and small aircraft, which has a door height difference of over 2 meters, the rotunda at the terminal end is positioned at the average height of the minimum and maximum door height of the aircraft which it is designated to handle.

Loading Of The Aerobridge

According to the Airport Equipment Ltd/ Jetway Systems General Specification, the maximum live load for the PBB is 195kg/m². The PPB need to also withstand a wind load of 122kg/m² (145km/hr) when unused and an operational wind load of 61kg/m² (97km/hr). A roof load of 122kg/m² is also required when technicians and engineers are required to work on the roof. The base of the tunnels comprise of corrugated ASTM-A36 medium carbon construction steel to withstand this load along with a centre beam running perpendicular to the corrugated patterns.

Future Designs

Although the Apron Drive PBB is sufficient for today’s aviation industry, improvements in design are being continuously thought of to minimize aircraft turn around time thus maximizing the usage of each single aircraft. This resulted in busy airports having 2 separate apron drive PBBs at each gate so that passengers may board and deplane the aircraft at a much quicker rate. Another improvement on existing apron drive PBB is the Glass Boarding Bridge where the side panels of the tunnels are made of glass. The main reason for this improvement is for consumer’s requirement as it provides passenger with a clear view of the apron prior boarding their aircraft.

Cost Advantage Over Old Method

As the technology has advanced from the manual moving stairs to truck driven stairs the advantages seemed to be enormous, until the development of the Aerobridges. Not only it has saved on turnaround time of each aircraft, it has helped the passengers to seamlessly move inside the airport before boarding the aircraft. Neither they have to bother about the freezing cold or the scorching sun while boarding and disembarking. The biggest advantage has been to the handicap people who don’t have to rely on attendants to carry them over the staircases. All these social advantages cannot over outshine the economic advantages it has given over the period of time.

We can discuss about the passenger buses from the terminus to the aircraft and elaborate about the advantages. As the airports have grown rapidly over the years, number of aircraft landing and taking off per hour has gone up. Just imagine, if a passenger bus have to travel 3km to the place where a 380 seater Jet standing, how many trips or how many buses are required to shift the passengers. What is the amount of fuel consumed for such one trip? If an airport handles 1,000 aircrafts per day we can imagine how many buses are required to handle the passengers coming in or going out of the airport. Now, multiplying it by the number of airports around the world will give an idea about the amount of fuel they would have consumed. This would deplete the reserves of our natural resources.

Let us elaborate it for our better understanding. There are around 45,000 airports around the world. Let’s say out of these 45,000 airports, 15,000 airports handle the air traffic of 1,000 aircrafts per day. If an average aircraft handles 200 passengers per trip then the number of passengers per day would be 200,000. If, 40 passengers are traveling at a time in the bus, number of trips from terminus – aircraft – terminus would be 5,000. Conservatively if we consider each trip is consuming 2 liters of fuel, then per day fuel consumption stands at 10,000 liters per airport. As we have considered 15,000 airports of similar capacity, the consumption of fuel per day stands at a staggering 150 million liters. If we consider full operation on 300 days per year then the consumption of fuel stands at 45,000 million liters. This is just by considering 33% of the total number of airports. As day by day the airports are growing, air traffic handling is also increasing.

To minimize the Global Warming, everybody is in a state of change to save every bit of carbon footprint. On an average, it has been estimated that every liter of fuel consumed is having a 2.5 kg of CO₂ emission.  So for 45000 million liters it stands at a staggering 112.50 million tones of CO₂ emission.

If we go a bit deeper, there will be at least 100 buses carrying the number of passages. The parking spaces for these are again a big problem, especially when there is a concept of best space utilization going around in every architectural design of the world.  Another big problem is the continuous maintenance of these buses which is much costlier than maintain the aerobridges.

Conclusion

An aerobridge has helped in conserving our natural resources and our environment at the same time. Just realize the importance of an architectural steel structural design made for only boarding and disembarking of passengers from aircraft to airport. It has come a long way since the first aerobridge was installed on July 29, 1959 at San Francisco International Airport. From aluminum to steel structure, has improved not only its strength but also the safety factors. As toughened glasses are now a day used for the sides, it gives a beautiful aesthetic look apart from the corrosion resistant property. There is no end to human thinking and who knows there might be something better in store for our future.