1. Tracy Johnson and Ian Savage (2006). Departure delays, the pricing of congestion, and expansion proposals at Chicago O'Hare Airport. Journal of Air Transportation Management 12(4):182-190.
[Journal Website]  [Manuscript Version]

Chicago's O'Hare airport is extremely congested, especially in the late afternoon and early evening. The paper uses a publicly available database to estimate the relationship between the number of flights wishing to depart and the delays they experience. This relationship is used to calculate congestion fees that provide airlines with incentives to move some flights out of the peak period and to slightly alter the scheduled departure time of other flights to avoid the rush of departures that occur on the hour. The very high fees at certain times of day point to the benefits that can be obtained from current plans to expand and reconfigure the airport to reduce delays in both good and bad weather.

2. Katherine Ashley and Ian Savage (2010). Pricing congestion for arriving flights at Chicago O'Hare Airport. Journal of Air Transport Management 16(1):36-41.
[Journal Website]  [Manuscript Version]

This paper estimates congestion fees for arriving flights at Chicago O'Hare Airport. The analysis finds that the level of congestion is only about a fifth of the magnitude of the congestion associated with departing flights. Congestion is much worse in poor weather conditions, and mitigating these weather delays is a primary objective of the current program to reconfigure the airfield. The analysis finds that the nonlinearities inherent in models of congestion mean that even a very modest change in flight patterns reduces delays and congestion fees quite considerably.