January 28th – Birmingham New Street Station is undergoing huge alterations at the moment, and is overrun buy people involved in the reconstruction. Sometimes, they almost seem to match in number the passengers; they emerge from hatches and previously unnoticed doorways, often surveying, taking measurements or gazing at ceilings. There’s clearly a lot of thought going on.
I keep noticing these tiny target symbols in odd locations about the station. About 20mm square, they have a precision cross-hair on them and a unique number , and they’re printed on reflective material. They’re vital to operations here, but I suspect few ever notice them.
They’re measurement datums. A theodolite – either placed in position by an engineer, or permanently sited in an out of the way spot – will focus on this target, and accurate geometrical measurements can be made, indicating if the target, or the wall it’s attached to, has moved, or to precisely locate some other measurement. Automatic systems will do this across multiple visible datums repeatedly, unattended, and alert engineers if there’s any change.
I suspect this is part of an automatic monitoring system as it’s above normal working, and therefore, crowd height, just to the left of the telephone kiosk roof.
Civil engineering is getting more and more sophisticated.
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