This is a nice easy and cost effective way of building some raised beds, in this case for vegetables. The oak sleepers measure in at 2.4m long, and 200mm x 100mm, and therefore are extremely heavy. They are just about manageable on your own if you’ve got thick enough arms, and have had a big enough breakfast. But I would always make sure there are 2 people available when moving them about for this exact reason. The beds are built with 6 sleepers each. They are 400mm high so are constructed 2 sleepers high, effectively built with 2 rectangular wooden rings. Each ring is 1 sleeper long, and half a sleeper wide. They are all connected using 4” posts in each corner, and with an additional one in the middle of the long lengths. 150mm screws are used to attach the sleepers to the posts, and will require a moderately powerful drill or impact driver to drive them in.
When overlapping the sleepers in the corners, always bond them together as if you they were bricks on the corner of a house wall. As the sleepers being used are 2.4m and 1.2m, this will always give you an outer dimension of 2.5m by 1.3m. If you build the bottom ring incorrectly with the small sleeper inside the long ones on both ends, or vice versa, you will not be able to replicate the dimensions on the 2nd ring whilst bonding the corners together correctly. So always take a few minutes to think this through before you fix them permanently.
All this was done in a long-ish morning with just the 2 of us, and will last for a very long time. Note that we did use the pro plas posts, as these will not rot. Next comes the job of filling them with soil, which will take a fair bit of effort at a later date. Hope this was informative, and thank you for your interest. As always, if you have any questions feel free to ask.