Thread by @thinkdefence

These are called concrete tetrapods. They are generally used for coastal erosion and wave protection, breakwaters and other coastal infrastructure, when placed on shorelines they interlock, forming a very durable and porous barrier that break up waves

Also hand (if you have the means) of creating temporary barriers on roads and tracks

Interlocking concrete 'lego' blocks are also readily available and easier to make and handle than the big tetrapods. Every village in Eastern Europe and the Baltics should have a stock of these. Instant road barriers to slow and channel enemy vehicles. Not perfect, but quick

The benefit of these over the really big concrete blocks is they can be lifted by much more common agricultural and construction plant.

Now are they perfect, of course not? But their aim is not to stop, it is to impede, make vehicle crews second guess or expend munitions to clear, or deploy scarce combat engineering units and equipment. They can also be quickly made with simple moulds

Are things like this free, no, they need resources and attention. Similar effects might be achieved by just digging up a road to create a big enough gap. But they do benefit from not requiring much maintenance and upkeep costs once in place.

Something to consider

As would IBC bulk bags filled with building materials, aggregates, stones and sand etc. Again, these are not perfect, far from it. But if they are prepositioned, not stolen in the meantime, they do provide a tick in the 'something is better than nothing' box

As I keep saying in this thread, things like this are a not a panacea, they are not free and very far from perfect. but numbers matter. Cratering charges are great, much more effective at blocking roads by making big holes in them. But they obviously require more specialists

And are you really going to proliferate these, probably not.

Hopefully, you see the point of this thread, perfect is fine, but quick, cheap and better than nothing is, well, better than nothing.

Preparedness is not just about people in green

/END

PS

Can I just make one more point, this isn't about what Ukraine should have done, it is what NATO should do. This, with much else besides