Estimation of uncertainty and variability of urban traffic volume measurements in Kielce

The results of traffic volume measurements from the permanent monitoring station located in Krakowska Street, Kielce, Poland are discussed in this paper. The traffic volume was measured over the period between January and December 2013 for twenty-four hours a day and with a sampling time of 1 minute. The results were subjected to statistical analysis. Type A uncertainty was evaluated. A new parameter, COV, positional variation and quartile coefficient of dispersion were proposed for the assessment of traffic volume variability. The studies of changes in traffic volume calculated for a 24-hour period during a year confirm that in the majority of the cases analysed, the results are not normally distributed. This may lead to imprecise determination of measurement uncertainty if ISO recommendations are followed. The calculated uncertainty ranges from 277 to 704 vehicles/24 hours. Traffic variability was assessed on the basis of the calculated values of the COV, V_q, and V_qlq3 parameters. The differences were recorded in the values and nature of changes, depending on the day of the week, between parameters COV and V_q. The proposed mathematical model of the variation assessed with the V_q parameter is consistent with the experimental data for evenings and nights. Some discrepancies on working days, especially between the values of COV coefficients for the day sub-interval were observed.