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Models and algorithms for transient queueing congestion at airports

Article Abstract:

A new, non-traditional queueing model is developed that could be used to study the phenomenon of congestion in a transient environment. It employs a recursive algorithm to estimate moments of queue length. The model is applied to the problem of aircraft landings at hub airports, which are often characterized by extremely high levels of variation rate over the day. Changes in the weather, the major source of uncertainty in service times, are treated both as a Markov and a semi-Markov process to explain the relationships between capacity levels at successive time intervals. The model is tested using real data from Dallas-Fort Worth International Airport. The results indicate that the model generates reasonable estimates. Its potential usefulness is demonstrated by examining the policy issues of schedule interference between two principal carriers, and the possible impact of demand soothing policies on queueing delays.

Traffic controls, Traffic congestion, Air traffic control, Queuing theory

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Two models for assessing a federal environmental health policy: the case of radon in U.S. homes

Article Abstract:

The U.S. Environmental Protection Agency (EPA) has been trying to minimize the public health risk of radon exposure by investing heavily in a public information campaign designed to convince homeowners to test and mitigate. Two models of the demographics of radon exposure in the US are developed for determining the public's response to this campaign. The first model examines the effects of important policy variables such as testing and mitigation rates on projected mortality over the next 100 years. The second model explores the perceived costs and benefits of mitigation for individual home-dwellers. Findings indicate that realistic policy scenarios result in moderate mortality changes and that the calculation of individual costs and benefits is not likely to bolster public response in any significant manner.

Health aspects, Analysis, United States. Environmental Protection Agency, Public service advertising, Public relations, Medical policy, Health policy, Radon, Health risk communication

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A "parallel approach" path to estimating collision risk during simultaneous landings

Article Abstract:

A study was conducted to analyze collision risk during simultaneous landings occurring on parallel runways that are only about half a mile apart. The simultaneous landings are designed to increase an airport's capacity by 50%. An estimation method was developed to determine the change that an airplane on final approach during instrument flight conditions will commit a mistake that would imperil nearby planes. The method combines the sampling of tapes about aircraft arrival path with controller dat on blunders. Results indicated that a sampling of 20% of simultaneous independent landings during instrument flight conditions for five years can prevent 75% of the avoidable error in determining the blunder rate.

Aircraft, Aircraft Manufacturing, TRANSPORTATION BY AIR, Air Transportation, Management, Air transportation industry, Civil aviation, Airplanes, Aircraft collision avoidance systems

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