No abstract

The article presents different methods of estimating DHV, including traditional Factor Approach, developed Regression Models and Artificial Neural Networks models. As explanatory variables: quantitative variables (AADT and the share of heavy vehicles) as well as qualitative variables (the cross-section, roads class, nature of the area, the profile of seasonal variations, region of Poland and the nature of traffic patterns) were used. In addition, the results of preliminary analyses of the DHV estimates based on the maximum hourly volume derived from a few hours traffic measurement on weekdays where there is the greatest share of hours with the highest traffic volume in the year were presented. On the basis of comparisons of the presented methods, Multiple Regression Model was identified as the most useful.

The characteristics of seasonal variations in traffic volumes are used for a variety of purposes, for example to determine the basic parameters describing annual average daily traffic – AADT, and design hourly volume – DHV, analyses of road network reliability, and traffic management. Via these analyses proper classification of road sections into appropriate seasonal factor groups (SFGs) has a decisive influence on results. This article, on the basis of computational experiments (models of artificial neural networks, discriminatory analysis), aims to identify which factors have the greatest impact on the allocation of a section of road to the corresponding SFG, based on short-term measurements. These factors are presented as qualitative data: the Polish region, spatial relationships, functions of road, cross-sections, technical class; and quantitative data: rush hour traffic volume.

The paper presents division of the road networks into homogeneous heavy traffic sections by the use of the qualitative and quantitative methods. At first, the cluster analysis is used to determine the initial factors groups. Next, these groups are modified on the basis of professional knowledge (geographic/functional assignment) in order to determine the factors, using which they can be easily identified. This division is the basis for the determination of conversion factors to convert short-term measurement into AADT.

1Missing traffic data is an important issue for road administration. Although numerous ways can be found to impute them in foreign literature (inter alia, the most effective method, that is Box-Jenkins models), in Poland, still only proven and simplified methods are applied. The article presents the analyses including an assessment of the completeness of the existing traffic data and works related to the construction of SARIMA model. The study was conducted on the basis of hourly traffic volumes, derived from the continuous traffic counts stations located in the national road network in Poland (Golden River stations) from the years 2005 -2010. As a result, the proposed model was used to impute the missing data in the form of SARIMA (1.1,1)(0,1,1) 168 . The newly developed model can be used effectively to fill in the missing required days of measurement for estimating AADT by AASHTO method. In other cases, due to its accuracy and laboriousness of the process, it is not recommended.