If we were to turn these pictures above in to an equation, or a ritualistic equation, we would first take the slogan on the wall - '5004LIFE' which presumably means 500 for life, then we would take the bridge number, 48 SBF.
It is unlikely that the slogan dauber realised that some of what he was writing was already there in the bridge number. Maybe he was influenced in some way.
The significant numbers are 4 and 5, with the letter F, which occurs in the word Life and the bridge number SBF. The slogan writer has also written 4 which if it was a word would be four or for which begins with the letter F.
So your 'magical' keyword would be 45F. 4 + 5 = 9 and 45 divided by 9 = 5
F is the sixth letter of the alphabet so 4 + 5 + 6 = 15
15/5 = 3 which is the same as the three components listed above which we have reduced to numbers.
Our area under the bridge then, has the magical number 456 so we can refer to it as 456. Incidentally, if we wanted to break this down even further 114 X 4 = 456 and 57 X 8 = 456, so our 8 will appear later in our working.
We would say that earth was the first component along with air, water was a secondary component, as in the beck and fire was in this case a tertiary component as fire may be represented in the ignition firing of the trains that run above and also of course in the sun (and if there was no sun nothing like this would exist anyway) but in this particular thing it is not as quite as obvious as earth or water as in the stone bridge or the slime beneath it.
456 is more important than you would think. A humble railway bridge, holding up the track, letting the trains pass, communicating from one area to another, so we could use the numbers 456 for communication, really a very important railway bridge, so we could use 456 as our communication slogan.
Of course you may bring a bit of smut along with it as in the underside of the railway bridge, but this is balanced equally by the top of the bridge and the communicating trains it carries, so 456 becomes a symbol of enterprise and balance. To refine it even more, we could use the figure 8, because 8 is an equal number and an equal sized symbol, the same above as below, reaching both earth and sky, grounding and balancing.
Therefore we can refer to the area covered by the photos above as 456-8 (- being a dash and not a minus sign) and this encapsulates the essences that the area stands for.