Splash and spray conditions created by tractor-trailer
combinations operating on the Federal highway system have been
studied and tested for many years with mixed results. Past events
are reviewed briefly in this paper. In additional testing during
1983, using new state-of- the-art splash/spray suppressant devices,
some encouragement was provided that these devices could work.
The 1984 Motor Vehicle Manufacturers Association (MVMA) test
program was designed to develop practicable and reliable test
procedures to measure effectiveness of splash and spray reduction
methods applied to tractor-trailer combination vehicles.
Over 40 different combinations of splash/spray suppression
devices on five different tractors and three van trailer types were
tested. The spray-cloud densities for some 400 test runs were
measured by laser transmissometers and also recorded by still
photography, motion pictures, and videotape. On-site observers made
subjective ratings of spray density. In general, this research
demonstrated that improved visibility can be achieved; however,
performance varied by vehicle configuration and could not be
quantitatively predicted.
This paper explores the complex relationship that exists between
the amount of spray generated and various vehicle aerodynamic
characteristics. Ambient conditions such as wind direction and
velocity and their effect on repeatability are discussed in
detail.