 Similarly, the driver can quickly act upon an unexpected downgrade, which may be the result of the signalman having returned the signal ahead to red in an emergency.Since CAWS is dependent on track circuits for its operation, it cannot be applied where axle counters are used for train detection (i.e., "mini-CTC" areas) without the additional cost.CAWS does not act in the event of a signal being passed at danger if the Red aspect has been acknowledged.