Abstract
A study to speed flow relationships has been established on nine lengths of 4-lane roads in Melbourne. Speeds were most effectively measured by a sample number plate survey technique. More than 88% of the variability in measured peak period travel speeds has been explained in terms of the significant traffic on physical factors. A number of potentially important factors was consciously eliminated in the pilot study: including road cross section type, horizontal and vertical alignment, speed restrictions, weather and driver characteristics.