Tram workers

I had 10 minutes to kill whilst I waited for my prescription. As my Chemist sits on the old west approach road from Haymarket to Princes Street, it's a perfect place to watch the tram work happening: which appears to be a lot of guys making sense of layers of cabling and pipework from different eras. (They uncovered a mass grave on Leith walk last year - now, whilst I'm not in agreement with the works in general, and get a bit frustrated with their unfastidious approach to managaing time and money - digging up a mass grave must bugger up your deadlines a bit). Everyone wears fluorescent jackets on site. Gaffers have clean ones with a blue border which reminds me of the tiling on stairwells in Glasgow closes. There are three colours of helmet which I am also curious about.