When passing a stationary special vehicle showing a blue beacon (without an audible signal), the driver must drive:
Explanation
A lit blue beacon without a siren warns you of a hazard ahead. As you approach such a vehicle, slow down and be ready to stop at any moment if the situation demands it.
KET reference: KET 187: When passing a stationary special vehicle showing a beacon, the driver must drive slowly enough to stop at once if needed, without endangering other road users.