Optimal Runway Exit Deisgn and Capacity Enhancement (1993)

Author: Dr. Byung Jong Kim

Relieving congestion of the air transportation networks requires several strategies to enhance the runway capacity. Among these strategies is reducing the runway occupancy time, a critical factor in affecting runway capacity.

In addressing the reduction of the runway occupancy time (ROT), complete information on the distribution of aircraft landing distance is required. A simulation model was built at Center for Transportation Research at Virginia Tech based on point mass kinematics in the flying phase over runway and the ground roll phase on runway to predict the landing roll distance and time to a specified exit speed. Many parameters were incorporated into the model, and then were calibrated using field data obtained from real operations.

The prediction of a nominal landing roll distance and time to decelerate to a specified exit speed is not sufficient for estimating ROT because the additional time to reach a designated exit should be taken into account. To compute the additional time, a braking adjustment scheme is selected from several alternative schemes. The combination of the selected braking adjustment scheme and the simulation model approximates very closely the observed ROT.

An optimization model is formulated to determine the exit locations so as to minimize the weighted average ROT of the defined aircraft mix. The major parameters for the model are the distribution of the landing roll distance to the specified exit speed and the information on the aircraft mix. The model is structured to address the problems of designing a new runway and of improving an existing runway.

A runway capacity model is used to convert the optimized ROT into capacity gains. Four scenarios are analyzed: one based on the present Air Traffic Control procedures, and three based on future developments. The capacity analysis reveals that the ROT does not affect the runway capacity for landing operations. However, the ROT is found as a critical factor for the runway capacity for mixed operations. Hence, the ROT should be optimized for the current system more crucially for the future developments. The capacity gains by optimizing the ROT under the current Air Traffic Control systems and standards are estimated 2 to 7 more operations per hour. These gains will increase to 20 more operations per hour in the future environment.

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