The mezzanine has load cells under its legs because it is rated for a weight and the weight moves around. They read the floor as an empty floor at night. Except at the far end, by the edge, where they read seventy kilos, standing, from midnight until about five, and the far end has had a fence on it since the year the cells went in.
I am the site safety manager at a warehouse with a mezzanine, which is a steel floor on legs halfway up the building, and the load cells are my idea.
Why.
A mezzanine has a rated load and people put pallets on it that add up to more than the rating without anybody doing a sum. The cells under the legs weigh the floor and where the weight is, and if a corner goes over, an alarm sounds and the forklift lift to it locks out. It was put in after a near miss, and it has stopped two overloads since, and I am proud of it.
At night it reads a person at the far end.
The reading.
Midnight to about five. Seventy kilos, give or take, resolved to the last three metres of the floor at the west end, the end that overhangs the goods in area, the end where the edge is. Standing still. The cells are sensitive enough to see a person shift their weight from foot to foot and, over the five hours, the reading shifts, a little, the way a person does who is standing for a long time.
Then, at about five, it goes. It does not walk off. Seventy kilos on the edge and then nothing, all at once, and the cells under the whole floor ring, the way they ring when a weight is taken off suddenly, the way they would if a person stepped off.
The fence.
The west end has a fence now, a proper barrier, chest high. It was put up when the cells went in, because the first month's data showed the seventy kilos at the edge every night, and I took it to the board as evidence that people were going up there after hours and standing at the edge, and I got a fence.
The fence went up. The reading stayed. It is on the wrong side of the fence, on the last half metre, on the lip, where there is not room to stand.
What has been checked.
The cells, calibrated. The floor at night, by me, with a torch, and the far end is empty and the fence is there and the reading on my phone is seventy kilos in front of me on the lip of the floor.
The camera. Shows the fence and the edge. Shows nothing.
The goods in floor below the edge, at five, by me. Nothing lands. The cells ring, on my phone, the weight is gone, and the concrete below is bare, and there is a smell, briefly, of the coffee they sell from the van in the yard, which does not come until seven.
Who.
The mezzanine was built in 2003. The fence at the west end was not, because the west end had no edge then. It was a walkway across to the offices, and in 2007 the walkway was taken down and the offices moved and the end was left open, and a man on the morning shift who had walked across to the offices every day for four years with his coffee walked across on the first morning the walkway was gone.
He was found at five past five, at the bottom, with the coffee.
What is done about it.
The night reading is logged as a sensor drift and the cell at the west end is on a replacement schedule, and the fence is inspected weekly, and the fence is fine, and he is on the other side of it.
What I do.
I run safety.
I have had a section of the walkway put back, a platform three metres out from the edge, railed, on legs, going nowhere, because the offices are not there. The board asked what it was for and I said it was a viewing platform for site tours, which it now is.
He stands on it. The cells are under the platform's legs too and the seventy kilos is on the platform now, at its far end, at its rail, from midnight to five. And at five, instead of the drop, the reading moves. Back. Along the platform, across the mezzanine, to the stairs, and down the stairs, and the cells under the stairs read a person coming down, and then nothing, at the bottom, where the door to the yard is.
He goes home. I have given a dead man a platform to nowhere and he walks to the end of it every night and looks at where his office was and then he goes home, and the coffee van man, when he comes at seven, has started leaving a cup on the platform rail, because he saw me do it, and neither of us has said why.