An experimental investigation of pollutant mass transfer from an open section in an intermittently covered depressed highway

This investigation was conducted to study sunken highways intermittently covered, with alternately open and closed sections. The objective was to investigate quantitatively the natural ventilation mechanism whereby pollutants are transferred to the atmosphere from the open sections. Such a highway is proposed for Interstate 1-40 through Overton Park in Memphis, Tennessee. This effort was conducted in support of that project for the State of Tennessee Department of Transportation. The effects of highway configuration as well as atmospheric variables upon the transfer rate were investigated.

A model of a sunken highway configuration with two opposing lanes of traffic was constructed. The model was installed in The University of Tennessee Space Institute (UTSI) water tunnel where the water flow through the test section was utilized to simulate the motion of the atmosphere. Model vehicles were attached to movable belts to simulate traffic movement.

The applicable dimensionless groups of test variables were found by an analysis utilizing the Buckingham n theorem. Correlation of the dimensionless groups was determined experimentally. A curve fit of the resulting data was best achieved utilizing a logarithmic relationship.