Just as with training heli pilots to do the more advanced tasks of mountain flying and SAR, you can do the same with Harriers. The RAF rarely use the GR 3 - 7 in the VTOL tactical role to save money. Once the guys are rated on their basic courses, they only do it operationally to ensure combat currency. That means that we could schedule closure of the M 50 for use of bridges for shelter ((!!))) and the Waterford road for use of tunnel / bridges for revetments. Also Cork tunnels and any other useful underground spaces for hidey-holes. You do this once a year. Otherwise, act like a normal jet. However, as quoted by a harrier pilot 'It's not a case of IF, but WHEN the engine fails', which is sobering. I cannot remember a RAF harrier engine failure resulting in a colateral damage incident.