I installed three of the new pine railway sleeper raised bed kits on a sloping site in my garden. This involved some digging out to get them level which has given them an attractive terraced appearance. I needed a heavy duty 1000 W drill to drive the timber lock screws straight in. This worked fine for the 8 inch screws but a 6mm pilot hole needed to be drilled for the 12inch ones.
Many thanks for the excellent photos and commentary of your raised bed project in construction. It's really useful to hear of your experience with the timberlok screws, and which ones needed a pilot hole to drill through the railway sleepers, and which didn't. As you say, the terraced appearance is really attractive and is a lovely addition to your garden.