CBTC+Fall-back

[soylemezv]

Thanks for reply. By assuming that system achieves a sufficient level of safety, based on the CBTC concept, ıs there any quantitive method to evaluate "availability" ?Point of view each component failure and impact of failure on the train operation ,as a consequence loss of revenue, comparing inital and operational costs of fall back system...How method should be used to decide fallback requirement?