> Given the number of cctv cameras that operate in the UK, and their continued growth,
CCTV cameras are mostly in private ownership, those in public ownership are owned by a mass of radically different bodies who will not share access without a minimum of police involvement. Oh and of course - we rarely point the cameras at the bridges (we have so many bridges).
> Where I live it is not uncommon for rail to have detection for people walking on the rail, and bridges to have extra protection against jumpers. I wouldn't be that surprised if the same system can be used to verify damage.
This bridge just carries trains. There is no path for walking on it. Additionally jumping would be very unusual on this kind of bridge; the big suspension bridges attract that behaviour.
You mentioned twice that you are surprised by things which are quite common in the UK. I don't know where you're from, but it's worth noting that the UK has long been used as a bogeyman by American media, and this has intensified recently. You should come and visit, the pound is not so strong at the moment so you'll get a great deal to see our country.
The saying/claims in the last 20 years or so is that London has the highest ratio of cameras to people in the world, through looking at what seems more correct statistics it is only the 12th most dense camera city in the world. how well that translate to the rest of the country is much less talked about.
Here in Sweden, people walking on the rails without permission is a fairly common problem, which cause almost 4k hours of accumulated delays per year. For people who often travel by train, the announcement of reduced speed because of the system has detected people on the tracks are one of the more common ones, only second to the catch-all announcement of "signal error", which simply mean the computer says stop for a reason that the driver don't know or don't want to say.
When it comes to suicide prevention on bridges, it is not just the big bridges. Suicide by train is a fairly talked methods in the news as a work hazard for train drivers, and the protection here is for small bridges that goes above the track. Similar issues exist with bridges over roads and highways. Those methods are to my read of the statistics more common than the movie version of a person jumping from a suspension bridge.