By Julie Cooper

Each month in “Slice of History” we feature a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

Freeway Tunnel Simulator — Photograph Number P-20673A

In October 1978, this photo was taken of a freeway tunnel simulator, which was used to study the air quality in freeways that were partly covered by buildings, streets or parks in an urban area. The Highway Intermittent Tunnel Simulator (HITS) project was carried out at NASA’s Jet Propulsion Laboratory under a contract with the Federal Highway Administration, Department of Transportation. A series of reports from this project were written to assist highway planning and design.

The simulator used electric motors to power two adjustable speed belts traveling in opposite directions, with 75 scale model automobiles attached. They could travel at about 40 “mph” (to scale) along a 110-foot straightaway. A gas was introduced into the tunnels to simulate exhaust fumes. Concentration and dispersion of the gas were measured as the automobiles moved through the tunnels. Test parameters such as distance between openings, type of traffic dividers and traffic speed were varied to see how they affected the air flow patterns.

At left is Bain Dayman, the HITS project manager. At right are Howard Jongedyk, FHA contract manager; Curtis Tucker, facility design engineer; and Robert Baxter, a contractor with AeroVironment, Inc., Pasadena. Most of the people working on this project were part of the Civil Systems Engineering Section at JPL.

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.