Page 321 - Software and Systems Requirements Engineering in Practice

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C C h a p t e r 1 1 : H a z a r d A n a l y s i s a n d T h r e a t M o d e l i n g 283
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Symbol or
Relationship Description Comment
Hazard This is a placeholder When activated, would either
for a hazard analysis. hyperlink to a hazard analysis or
open the hazard analysis if the
model and analysis are in the
same tool.
Mitigating Identifies a The requirement could be entirely
requirement requirement is needed in the model or could be a
to mitigate the risk of placeholder for a hyperlink to the
a potential hazard. requirement in a requirements
database.
Mitigates A mitigation This relationship can take the
relationship place of manually entered and
between a hazard maintained traces.
and a mitigating
requirement.
Impacts An impact relationship Indicates that the mitigating
between a mitigating requirement may constrain
requirement and or otherwise impact another
another requirement. requirement.
TABLE 11.3 MDRE Extensions for Hazard Analysis
A Cautionary Tale
On July 12, 2006, the ceiling of a portion of a tunnel (the “Big Dig”)
in Boston fell on a woman’s car, killing her. An investigation revealed
2
that the wrong glue had been used to fasten the ceiling panels. Each
of the organizations and staff that were involved in the construction
of the tunnel blamed other parties. Finally, the company that supplied
the glue was charged with involuntary manslaughter. As there were
3
no traces from requirements through construction, it was not possible
for project management to trace from the installation back to the
correct type of glue needed (the correct glue needed was known and
recorded at the start of the project). We can learn from this tragedy:
• People can be held criminally liable for failure to follow best
practices.
• Hazard analysis coupled with effective trace mechanisms can
potentially save lives.
2 July 12, 2006, edition of the Christian Science Monitor.
3 August 9, 2007, edition of the Boston Globe.