Something that Ive noticed is the amount rail archs with pigeon nets - in SE1, almost all do, SE16, none. Even the bridge the borders the postcodes (abbey street), doesnt have them. These rodents make a huge and disgusting unhealth mess and yet then council dont seem to want to take any proactive action? Why?
Apparently it is not the council's responsibility to carry out the fitting of the pigeon nets you are referring to, it is the responsibility of Rail Track or whatever they are called now.
The good news is that under the new legislation of the London Local Authorities Act 2004, if Rail Track do not carry out their responsibility of keeping the bridges clean and pigeon free, then the Council can carry out the work themselves and give Rail Track the bill.
Hopefully this will persuade Rail Track to fulfil their responsibilities. We will have to wait and see.
I suspect if there is any disparity in the state of railway arches and bridges in SE1 compared to other areas it is because many grotty bridges in this area have been cleaned up by regeneration bodies such as the Cross River Partnership, Better Bankside and so on.