Preliminary Hazard Analysis (PHA).
Failure Mode and Effect Analysis (FMEA).
Failure Mode Effect and Criticality Analysis (FMECA).
Hazard and Operability Studies (HAZOP).
Risk Screening (HAZID sessions).
In addition to these, scenarios may also be identified on the basis of past experiences as
reported in so-called incident data banks containing a systematic documentation of events
leading to or almost leading to (near misses) system failure events.
Even though none of these methods were developed specifically for risk analysis in the civil
engineering sector numerous applications have proven their value in this application area also.
In the following a short description of classical techniques (PHA, FMEA, FMECA and
HAZOP) will be given based on Stewart and Melchers (1997) and thereafter the risk
screening methodology which contains aspects of all classical techniques will be described.
Finally a discussion is given in regard to the issue of hazard identification in the area of civil
engineering applications.
Preliminary Hazard Analysis - PHA
Preliminary hazard analysis are usually conducted on a qualitatively basis during the
conceptual stages of projects for the purpose of identifying the major hazards for the
considered engineering system and/or activity together with their causes and the severity of
their consequences. However, PHA may also be used as basis for the reassessment of risk and
reliability of engineering systems, which are already in use.
The results of a PHA is often summarised in tabulated format containing lists of:
Hazardous elements.
Event, which might initiate the hazardous situation.
Specifications of the hazardous situations.
Events scenarios leading to failures as a consequence of the hazardous situation.
Specification of the failures.
Specification of the consequences of failures.
Measures of risk treatment.
Due to the qualitative nature of a PHA the sub-systems and components will usually not be
ranked in regard to criticality but the results of the PHA provide the basis for doing so using
other methods such as FMEA, FMECA and HAZOP.
Failure Modes and Effect Analysis - FMEA
FMEA was developed originally in the aeronautical industry and forms by now together with
FMECA as described later the main framework for hazard identification in a variety of