Does anybody know the weight of a trench block? Surely they are over the legal hand-lifting limit?

Answer 1

In the UK there are no legal limits for objects based on weight. Check the H + S it a fallacy that people state 25Kg or 20Kg. These are the advisable weights and %age reduction tables for full swing lifting (check your anthropometric drawings) for a 90%tile and you get the advisable weights and at which 'zone' relative to the body i.e lifting from the hip or from the floor.

The bottom line is comfort and repeatability which varies person to person.

Answer 2

Trench Block: A obstacle made to be placed in a trench to hinder the movement of enemy raiding parties. Trench blocks were commonly found in communications trenches. They were usually kept out of the way of movement until a trench was in danger of being overrun. If the trench was overrun, the retreating defenders would put the block in place and move to a support position.

Definition is found in first link ... sketch is shown in second link.

From the sketch, I'd estimate the "cross" to be made of something like 4x4 beams, approximately 4 feet long. Add the stake (a 3 inch peg maybe 2 feet long), and perhaps 20 feet of barb wire.

Wood densities range from spruce (at 450 kg/m3 = 28.09 lbs/ft3) to elm (at 600 kg/m3 = 37.46 lbs/ft3).

At the low end (spruce), we'd have:
(2 beams at 0.444 ft3) + (1 stake at 0.393 ft3) + 20 ft barb wire
= (2 * 0.444 * 28.09) + (0.393 * 28.09) + (20 * 12 * 0.25 * 0.281)
= 52.86 lbs

At the high end (elm), we'd have:
(2 * 0.444 * 37.46) + (0.393 * 37.46) + (20 * 12 * 0.25 * 0.281)
= 64.88 lbs

Are these above the legal lifting limit? Depends on where you are. But my guess would be that these were manhandled into position by teams of two, rather than by individuals.

Answer 3

I don't know what sort of Block a Trench Block is,sorry!!!

Answer 4

they weigh aroud 21kg dry (3% moisture) and a couple of kilos more if around 10%.

Legal limit is around 30kg.