Are there any reference sources for the typical installation costs of runway overruns, and variables which would affect their efficacy?
The ones at JFK do seem to have been very effective, but multiplying by 12 for a six runway airport, or applying these on less heavily used or loco "friendly" airfields cannot be cheap.
Is MAN the only place in the UK to have them, or are they elsewhere? The beancounters would presumably have done a CoBA on these, which must surely be more likely to be positive at heavily utilised single runway airfields like LGW?
As for the reference that this event "could have been another Kegworth", iirc there were no ground fatalities due to this incident, weather conditions and runway usage notwithstanding.