I know there's a warning here for using the barrier=block tags on two line ways in lieu of node points, but I don't know of any better tagging to use in such a situation. In reality what's there is two courses of these types of interlocking concrete blocks: https://concrete-security-barriers.co.uk/lg-interlocking-concrete-barrier/

... plus a metal fence on top of it. The fence and the blocks are partially contiguous, but not entirely, which is why I mapped them as separate ways.

If someone has a better idea of what to do, feel free to change it!