product or service. For normal users, reliability means that a service has a high
probability of being available in the quantity, quality, and at the time required.
Exposition of the economy to foreign competition imposes stricter requirements,
particularly on the reliability and quality of most activities, including infrastructure
services, compared to local demands or those prevailing in a closed economy. Developing countries need significant improvements in infrastructure quality if they wish to
participate effectively. These improvements are essential given that more than 80% of
their exports go to developed countries. Physical infrastructure, such as roads, rail, air,
and marine transport, telecommunications, power, becomes a pre-requisite for productivity growth and successful international competition. The chapter finally explains the
approaches to increase the reliability of infrastructure systems.
9.1 Quality and Reliability in Infrastructure
When civil and environmental engineering systems are evaluated, it is necessary to
assess whether the designed system can meet project requirements or satisfy users’
demands. System performance failure may arise for a number of reasons, including:
(1) natural hazards.
(2) lower performance than predicted.
(3) collapse of major structures.
(4) dam break due to a catastrophic flood that exceeds the design value.
(5) structural failure attributable to faulty design.
(6) more complex reasons e.g. Malpasset dam, France, in 1959, where the right
abutment gave way, due to geotechnical reasons. A major landslide in 1963
caused the Vajont dam, Italy, to overtop and cause a flood downstream. In both
cases, casualties were high.
Although engineers try to ensure system performance and safety of infrastructure,
the accepted adequacy levels or risk are constrained by economic and social factors.
Therefore, it is important that planning and design of engineering systems be
accompanied by accurate cost-and-benefit analyses so as to achieve a complete
evaluation of system performance and safety. Social issues also constitute a significant role in the evaluation of civil and environmental engineering systems, as they
are more directly concerned with the public, in contrast to other engineering systems.
Defining when the system becomes unable to perform adequately, such that
failure results, is quite difficult. For example, if a dam breaks, the associated failure
can occur immediately. Sometimes, repairs can be effected; in other cases, the
damage cannot be repaired. In contrast, even, if a road undergoes occasional traffic
congestion, it will operate normally again after the conditions, causing the congestion, are removed. This does not preclude a similar failure, at some other time, in the
future. In a wastewater treatment plant, failure may occur very gradually, that it is
very difficult to subjectively assess the stage at which the plant stops performing
satisfactorily. In the above cases, the decisions comprise some additional uncertainty
when defining the system performance and safety, as well as the judgment of the
decision makers, who must weigh possible benefits against costs.
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9 Quality and Reliability of Infrastructure
probability of being available in the quantity, quality, and at the time required.
Exposition of the economy to foreign competition imposes stricter requirements,
particularly on the reliability and quality of most activities, including infrastructure
services, compared to local demands or those prevailing in a closed economy. Developing countries need significant improvements in infrastructure quality if they wish to
participate effectively. These improvements are essential given that more than 80% of
their exports go to developed countries. Physical infrastructure, such as roads, rail, air,
and marine transport, telecommunications, power, becomes a pre-requisite for productivity growth and successful international competition. The chapter finally explains the
approaches to increase the reliability of infrastructure systems.
9.1 Quality and Reliability in Infrastructure
When civil and environmental engineering systems are evaluated, it is necessary to
assess whether the designed system can meet project requirements or satisfy users’
demands. System performance failure may arise for a number of reasons, including:
(1) natural hazards.
(2) lower performance than predicted.
(3) collapse of major structures.
(4) dam break due to a catastrophic flood that exceeds the design value.
(5) structural failure attributable to faulty design.
(6) more complex reasons e.g. Malpasset dam, France, in 1959, where the right
abutment gave way, due to geotechnical reasons. A major landslide in 1963
caused the Vajont dam, Italy, to overtop and cause a flood downstream. In both
cases, casualties were high.
Although engineers try to ensure system performance and safety of infrastructure,
the accepted adequacy levels or risk are constrained by economic and social factors.
Therefore, it is important that planning and design of engineering systems be
accompanied by accurate cost-and-benefit analyses so as to achieve a complete
evaluation of system performance and safety. Social issues also constitute a significant role in the evaluation of civil and environmental engineering systems, as they
are more directly concerned with the public, in contrast to other engineering systems.
Defining when the system becomes unable to perform adequately, such that
failure results, is quite difficult. For example, if a dam breaks, the associated failure
can occur immediately. Sometimes, repairs can be effected; in other cases, the
damage cannot be repaired. In contrast, even, if a road undergoes occasional traffic
congestion, it will operate normally again after the conditions, causing the congestion, are removed. This does not preclude a similar failure, at some other time, in the
future. In a wastewater treatment plant, failure may occur very gradually, that it is
very difficult to subjectively assess the stage at which the plant stops performing
satisfactorily. In the above cases, the decisions comprise some additional uncertainty
when defining the system performance and safety, as well as the judgment of the
decision makers, who must weigh possible benefits against costs.
254
9 Quality and Reliability of Infrastructure