Information Technology Reference
In-Depth Information
2
Application of BP-Risk for Hot Box Detection
2.1
BP-Risk
BP-Risk is a semi-quantitative approach for railway risk assessments, which
has been published [2] and validated [1].
Semi-quantitative methods are a combination of qualitative and quanti-
tative approaches. In [9], they are defined as “qualitative, model-based” risk
assessment methods. This means, that for semi-quantitative risk assessment
methods, numerical (quantitative) values are assigned to qualitative scales.
Examples for semi-quantitative risk methods can be found in the auto-
mobile industry and in the IEC 62061 [8] standard “Safety of machinery”.
For BP-Risk semi-quantitative implies, that on the outside, the risk ana-
lyst uses the front-end tables, provided by BP-Risk to assess the risk param-
eters. On the inside, there exists a risk model, which is implemented in the
tables and actually uses numerical input values. Therefore BP-Risk uses the
following risk model:
R
=
f
·
g
·
s
(1)
where
f
is the hazard frequency - expressed as a Tolerable Hazard Rate
(THR),
g
is the probability, that the considered hazard leads to an accident,
and
s
represents the potential damage.
The two risk parameters
g
and
s
are divided into sub parameters to ease
their assessment.
The general approach for risk assessments with the help of BP-Risk in-
cludes the common aspects (as required by standards and regulations):
- System definition
- Hazard identification
- Consequence analysis with BP-Risk tables
- THR derivation with BP-Risk table
These steps are described in the following for the application of BP-Risk
for the safety requirements of hot box detection systems. It has to be noted,
that this is not a complete risk assessment, but that this paper tries to high-
light the most important aspects and tries to bring out some first reasonable
results.
2.2
System definition
Hot box detectors can be interpreted as monitoring devices to ensure the
track guiding by measuring temperature as an indicator for failures at boxes
or brakes. Thus the hot box detectors have to recognize if the temperature
is exceeding a specified threshold. The considered function could be called:
“hot box detection”.
For this paper, the following assumptions were made:
