5.3 Uncertainties in railway design parameters
5.3.1 Allowance for uncertainties
The uncertainties described in the following clauses may be allowed for by adopting limiting values of
parameters or by incorporating a safety factor into the design process. This safety factor, designated S, shall
then be applied when comparing the calculated stresses to the permissible stress as indicated in 5.4.
NOTE In the design process the following should be considered with respect to criticality of the component failure:
consequence of failure, redundancy, accessibility for inspection, detection of component failure, maintenance interval, etc.
The value of S shall be chosen to include the cumulative effect of all uncertainties not otherwise taken into
account.
5.3.2 Loads
All loads used as the basis for vehicle body design shall incorporate any necessary allowance for
uncertainties in their values. The loads specified in Clause 6 include this allowance. If the design loads are
derived from on-track tests or other sources of information an allowance for uncertainty shall be used.