AP-G84/04 Best practice in road use data collection, analysis ... - WIM

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Accessed by AR - ARRB TRANSPORT RESEARCH on 04 Feb 2005 Austroads 2004 — 26 — Best Practices in Road Use Data Collection, Analysis and Reporting The factoring process defines a set of roads as a ‘group’. All roads within that group are assumed to behave similarly. Then a sample of locations on roads from within that group is taken and data are collected. The mean condition for that sample is computed and that mean value is used as the ‘best’ measure of how all roads in the group behave. If the sample of data collection sites is randomly selected and moderately large, the distribution of that measure about the mean is a good measure of how well that mean applies to road sections in the group (FHWA 2001). The definition of a homogeneous road section is complicated by differences between rural and urban sections across a State and region. Homogeneity can be derived from functional classes as well as from stratification by volume. Various homogeneous groupings include those in Table 12 by functional classes and Table 13 by AADT strata. US FHWA (2001): • interstate rural • other rural • interstate urban • other urban • recreational Table 12 - Groups by functional classes: Canada (Martin and Chiang 2002) • regional commuter • average rural • partially recreational • recreational New Zealand (Transfund NZ 2001) • urban arterial – major, minor • urban – commercial, industrial, other • rural urban fringe • rural strategic • rural recreational – winter, summer VicRoads is implementing a classification system for its declared road types based on uniform road geometry and performance specifications to invoke consistent user expectations. The road network then becomes a set of clearly stratified sub-networks each of reasonably similar AADT. Table 13 provides the current Austroads guide on deriving homogeneous sections based on AADT volume data, categorised by urban and rural roads. In the study on traffic counts for RTA, Botterill and Luk (1998) found that the rural AADT strata of (0, 100) and 7,000-plus could be expanded to give better estimation.
Accessed by AR - ARRB TRANSPORT RESEARCH on 04 Feb 2005 Table 13 - Suggested volume stratification of road segments Stratum Suggested range for urban roads (AADT) 1 2 3 4 5 6 7 8 9 10 0-300 301-1,100 1,101-2,000 2,001-4,000 4,001-7,000 7,001-16,000 16,001-20,000 20,001-35,000 35,001-50,000 50,000 plus Austroads 2004 — 27 — Best Practices in Road Use Data Collection, Analysis and Reporting Suggested range for rural roads (AADT) 0-100 101-300 301-700 701-1,100 1,101-2,000 2,001-4,000 4,001-7,000 7,000 plus Homogeneous or uniform traffic sections should be determined in a consistent way based on a predefined set of rules. Road authorities would have their own individual procedures in defining and processing homogeneous sections. An example of rules for defining homogeneous traffic section, sourced from Main Roads WA and Transit NZ and reported below. those rules can be used as a starting point to generate traffic sections that can be reviewed by stakeholders with local knowledge for consistency and accuracy. Each homogeneous section to be selected up to its maximum length, including ramps; Homogeneous sections to be delimited by intersections with arterial and sub-arterial roads; A homogeneous section should not extend over two roads; A homogeneous section should not contain a single and dual carriage way or a ‘one-way’ road; A homogeneous section cannot span across different speed zones The start and end points of homogeneous sections should not coincide with start and end points of strategic links (cannot have a homogeneous section overlapping the lengths of two consecutive strategic links); and A difference in AADT volumes between two consecutive count sites of 15 - 100% generates a new traffic section, as shown in Table 14. Similar rules can be applied in regard to traffic composition.
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AP-G84/04 Best practice in road use data collection, analysis ... - WIM

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