Passenger capacity and constraints

Runways

Capacity constraints on airports, however, can and do show up on taxiways, aprons, and jetways. Runway capacity, for example, depends heavily on how quickly an aircraft can leave or enter the runway. Many African airports deploy a low-cost design as shown in figure 2.3. Instead of the aircraft leaving the runway via a turnoff after landing, the aircraft must taxi to the turning bay, turn around, and taxi toward the access to the apron usually found in the center of the runway. This is perfectly acceptable in an airport where there is enough time between departing and arriving aircraft to do so, but high-volume airports require parallel taxiways with multiple turnoff ramps from the runway. In addition, if parking space on the apron is limited, an airport can quickly come to a standstill.

Figure 2.3 Abstract of a typical airport design commonly found in Africa. The runway will feature turning bays, with a central apron for the terminal and parking. Many airports of this design exist, with different variants.

Source: Author

One common, and sensible, solution for airports with the turning bay configuration is to construct a parallel taxiway. In fact, constructing a new parallel runway and using the old runway as a parallel taxiway is a common solution, particularly in North Africa, and now also being adapted elsewhere. Figure 2.4 shows the new configuration. During construction, the runway continues service without interruption. Once the new runway is in service, the old runway serves as a parallel taxiway. If maintenance is to be performed on the new runway, the old runway can resume its duty as a nonparallel taxiway runway.

Source: Author

Terminals

In some cases, remedies to the capacity issues are already being implemented. For example, Nairobi’s passenger terminal is going through an extensive upgrade allowing over 9 million passengers. In other cases, further examination of the actual circumstances of the airport must be made. Beyond new terminals, rescheduling of flights in a manner that does not have too many flights arrive at the same time may be in order. At other airports, capacity issues should be looked at carefully. Malawi’s airport in Lilongwe, for example, though clearly in need of some upgrades, is not a limiting factor in passenger capacity.

The overall assessment needs to be made on a case-by-case basis. One industry general assumption in airport planning is a terminal surface of 20 square meters per international traveler, or applying a ratio of 0.007 to 0.01 to the overall annual passenger number. Formulaic statements such as this would lead one to assume that by applying these constants to known sizes of terminals and passenger numbers one could conclude the overall terminal capacity. However, this assumption cannot be made since there are too many variances and different forms of bottlenecks in terminal design. If complaints about terminal constraints are raised on an individual basis, though, an easily quantifiable measurement would be the balancing of the terminal usage over time. In looking at the distribution of arriving and departing flights for November of 2007 at the primary airport of each of the 53 countries examined, it becomes clear that generally, the lower the maximum flights per hour, they less well distributed the scheduling becomes. For example, a higher density airport such as in Addis Ababa will show a better (more even) balancing of flights than, for example, Cotonou, Benin, where the highest number of flights per hour was observed at four, eight times the average over the week. Appendix 8 shows a list of the main airports per country, with a general grading on the balance of scheduling after examining flights and seats with regards to peak hour usage for one week in November 2007. In at least 26 of the 53 airports examined, the schedule of arriving and departing flights could be re-examined in order balance the usage of the airport. At 12 airports traffic never exceeded two flights per hour, generally making the distribution analysis a moot issue. However, it must be cautioned that arrivals and departures are treated equally in this analysis, though different operational areas of the airports would be involved. This implies that, for example, two flights per hour may represent one departing and one arriving flight, only one flight being handled at the same time in the respective terminal area.

One unknown factor in Africa is if there will indeed be a contraction, rather than growth, in the air transport industry as fuel prices perhaps rise again or the world economy contracts. Many projections in recent months have been becoming gloomier as fuel costs were soaring, and though this crisis has eased, the impact of the economic slowdown will still have a significant impact..¹⁴ However, evidence for 2008 still has shown continued growth for the year.