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

Accessed by AR - ARRB TRANSPORT RESEARCH on 04 Feb 2005
Austroads 2004
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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.