With regarded to fences, they are in response to everyone that has been saying 'something must be done'. Therefore the TOCs and NR have done 'something'. Whether they are effective or not, well I'm told the Samaritans say they are, but I guess we don't know how many decide not to take their life on seeing these fences.
There has been much study done into this subject recently. The evidence suggests that many suicides are 'opportunistic' if you will pardon the choice of phrase, ie someone going through a difficult time takes a split second decision to, in this case, jump in front of a train. Clearly this isn't the case for all, or even most suicide attempts on the railway.
It does follow, though, that if you put the fences up, it makes it more difficult for the 'opportunistic' to take their lives. It is also easier for staff to spot someone on the wrong side of the fence, and do something about it.
In this respect saving one life is a good result, primarily for the individual concerned, but also those who would have been affected.
Evidence from the first fences @ Purley / Purley Oaks has shown a notable reduction in suicides at these places. It is subject to the law of small numbers, but the signs are good.