Information Technology Reference
In-Depth Information
Usually derailments of a freight train don´t lead to harm of persons but
only to damage to property. Hence, we can estimate the number of affected
people to be a no person but only damage to property, which is not considered
by BP-Risk at this stage. That corresponds to A having the value of 0.
But it has to be noted, that follow up events like collisions or even fire of
dangerous goods are not considered here, because those would be worst case
scenarios which have a very low frequency of occurrence. BP-Risk uses typical
scenarios, which lead to typical consequences. If worst case scenarios would
be assessed, there is no need for a method like BP-Risk, because one would
have to derive the highest safety requirements anyway which lead unnecessary
high costs for the components.
Tabl e 5 . Number of affected persons (Parameter A)
A
number of affected per-
sons
example
1
single person
collision with obstacle (not other
train)
2
few persons
collision at level crossing
3
several persons
derailment
4
many persons
5
very many persons
head-on or end-on collision (of
trains)
Parameter S can then be calculated by adding the three subparameters:
S = T + V + A = 0 + 3 + 0 = 3. Altogether the sum of G and S is 6 + 3
=9.
3
THR Derivation
To derive the THR for the considered function, Table 6. is used. The sum
of G and S corresponds to a certain tolerable hazard rate (THR). For our
example, this would be THR =
3
·
10
−
5
/h
. Note, that BP-Risk uses RAC-TS
as a risk acceptance criterion which was implement in Table 6.
It is important to note, that the hot box detection is not determined to a
technical component only at this stage. The function itself can be carried out
by on-site staff only or by technical components or a combination of the two
although there would be differences in reliability and availability. Moreover
networked technical components would allow trend analysis and therefore
a higher level of operational safety and performance. In case of networked
components, an in depth analysis would have to take into account that the
devices are “connected” with each other.
Also an in depth analysis would have to consider the aspect of having only
technical wayside components. For this example, we assumed as a simplifica-
