Abstract:
The average daily traffic (ADT) is utilized as an important basic data in transportation and
road sector to predict the future service level of the road based on the planned traffic volume and to
determine the geometry of new roads. As the installation of traffic counters to obtain long duration
volumes like ADT is expensive, carrying out a short duration survey and extrapolate the volumes to
ADT would be more economical. Use of “Expansion Factor Method” to extrapolate short duration
volumes to ADT will be discussed in this research. The analysis was carried out using 148 count
stations located at national AA roads, dividing them into three categories based on their flow
variations. The expansion factors for 1h, 2h, 3h, 4h, 5h and 6h durations and the best time interval to
carry out the survey for each time duration were found. Using 37 locations the results obtained from
the analysis were validated and the comparison between the actual ADT and the calculated ADT
shows the results from the research are satisfactory.
