Showing papers in "Journal of Transportation Engineering-asce in 1978"

Deformation of lime modified clay after freeze-thaw

Abstract: The addition of small quantities of lime to a subgrade soil greatly improves its resistance to deformation which has been found to be extremely useful during construction under wet conditions. Soil suction, dynamic strength, and resilient characteristics of a glacial till commonly used for highway subgrade construction were studied experimentally. Changes in material properties resulting from variations in water content, lime content, confining pressure, and deviator stress intensity before and after subjecting the material to freezing and thawing were the variables considered. The results of the study indicated that the resilient characteristics of the till were so greatly improved due to the addition of lime that under certain conditions, a lime stabilized layer within a pavement structure would likely fail in tension and that the material could eventually behave essentially as a granular material.

Tandem-queue algorithm for airport user flows

Abstract: A method is presented for relating, using simple functional notation, the cumulative arrival patterns of passengers at two successive sets of airport processing components. An algorithm is developed for the simplest case where all passengers go directly from one component to the next. In the algorithm there is provision for superimposing the arrival patterns of passengers of many different flights. The recursive equation of the algorithm is then generalized to accommodate more complex patterns of passenger flow with ancillary activities. A method is developed for estimating the total expected time spent between such processors as a function of the probability that passengers use particular ancillary activities, the associated dwell times at each, and the time spent going between activities. The overall algorithm is analytic and is intended for tying together deterministic queueing models of individual components so that the passenger flow through an entire airport can be analyzed.

Model of airport employee access traffic

Abstract: Previous research on airport access has not focused adequate attention on airport employee traffic considering that airports employ nearly one person per daily enplaned passenger. This paper provides a tool that can be used to estimate employee traffic volumes in specified time intervals as a function of employee work shift characteristics. Inputs to the model include work-shift times, the number of employees per shift, probability distributions for the times at which employees actually arrive at and leave work, and the average number of employees per vehicle. The model is designed for use in conjunction with models of air passenger and visitor traffic. In particular, it can be used to investigate the potential for mutual interference of employee traffic peak and air passenger traffic peaks. A demonstration of the model is presented using data collected at the Dallas/Fort Worth Regional Airport; model estimates are compared with actual traffic counts of employee vehicles.

Airport/community environmental planning

Abstract: An analysis of recent airport environmental planning practices shows that they have been fundamentally misdirected. Emphasis on the preparation and review of Environmental Impact Statements by governmental agencies with narrow aviation perspectives has resulted in widespread litigation and controversy. A new approach is needed, one that leads to a closer integration of airport planning and comprehensive urban planning. A systematic definition for the term environment serves as the basis for such an approach.