We had a similar experience a number of years ago travelling to Narita by train in Japan. The electric overhead wires were brought down some where between us and the airport. We allowed more than four hours spare (nominally 6hrs) in our schedule to make the flight, thinking that qualified for a delay.
By luck our train eventually limped into Nagoya, where we abandoned our Super Express, and paid two fares from the local airport direct. We made the connection with minutes to spare. The fine print as per @PhilT then denied us any claim for the extra flight costs, and if we had missed the flight any other compensation.
When offering us travel insurance for this trip and others prior no travel agent ever explained how this scenario was not covered. The TA pushed the line re the coverage for delays etc, without explaining the very broad range of exclusions that make it next to useless.
I also now understand why on overseas trips the TA always seemed to find an excuse to have us stay the last night next to the airport. Usually also the most boring place imaginable!
I recollect that Choice has some great advice on this in the travel section.
We now book 90% of all travel direct and purchase travel insurance based on Choice reviews. It is possible to mitigate connection risks with overnight stays or occasionally flying on a premium fare for critical connections. Possibly a better use of points too.
