Seasonal variation in traffic flows is defined as the ratio of the average daily flow for each month to the annual average flow. Its variation by day of week is examined using analysis of variance techniques on data from the 50-point census. Five sets of ratios for each site are calculated, representing the seasonal variation for Mondays, Tuesdays to Thursdays, Fridays, Saturdays and Sundays. The sites of the 50-point census were grouped (seven groups for weekdays and six groups for weekends) using these sets of ratios by Beale's cluster analysis. This grouping did not have any obvious physical interpretation so a more subjective method of grouping the sites was devised. This produced four groups of more practical use corresponding to different types of traffic: urban/commuter, low-flow rural, rural long-distance, and recreational. Seasonal variation patterns are tabulated for these four groups for Monday to Friday, Saturday and Sunday. These patterns can be used to estimate annual average daily traffic flows more accurately than previously when factors for only a single road type were available. (Author/publisher)
Abstract