As water distribution infrastructure ages, utility managers
must weigh the benefits and costs of pipe repairs against
those of replacement. Although models have been proposed
to help managers make these decisions, they have not been able
to incorporate the environmental and geographic factors that
influence infrastructure condition. This article introduces a diagnostic
tool that uses system data and pipe break records to help
managers identify regions across the network that contain aggressive
environments and that may be most prone to failure.
The aggressivity index (AI) is an indicator based on historical
network performance. Spatial disaggregation is used to assess
variability within the network; observed break data are used to infer
variable aggressivity across the domain. The AI enables current and
potential influences of aggressive environments to be factored in
without the need to explicitly identify and measure physical properties
that may influence degradation of cast-iron pipe networks.
Development of an effective pipe replacement schedule is
impossible without insight into the current and future state of
deterioration. For systems with a low rate of pipe failure, network
monitoring or quantification of influential factors may be almost
as expensive as pipe replacement. The AI provides an alternative
to costly monitoring-based approaches to main replacement and
enables utility managers to compile an efficient replacement
schedule that targets pipes in specific areas. Includes 26 references, table, figures.