Looks like a temporary fence to separate part of the airfield from airside. There has been the odd digger working parallel to Delta for months now just digging random ditches and then nothing for weeks. Maybe this is indeed the start but when Bravo was extended all of the work was kept airside.
Work was meant to have started July as per the tender and includes de-icing pads / pavement
https://www.theconstructionindex.co....tice-codenuts-