Railway bridge

I wandered off down Kingston Lane, a road near me which I hadn't been down for many years. As far as I could recall there used to be a simple bridge that went straight across the railway lines. Now it was replaced with some monster structure which zigzagged up high above. At the top is a tunnel which as you can see from the photo is enclosed by a kind of grid, obviously to prevent people of jumping off and committing suicide.

The structure is surrounded by scaffolding suggesting it's an unfinished work in progress (see below).