On Friday, 26 March 2021 at 07:20:51 UTC, Mike Halmarack wrote:

Rush hour's a torment when you've got one of these seveal feet away.
I tried several things: pouring sand between the frame and the lid,
which worked for a while, expanding foam with similar effect.
In the end it had to be a replacement.

I've noticed that all the manhole covers on our 'new' (2007) estate are made up of two triangles, presumably as each piece is unable to rock regardless how ill fitting they might be/become. That or some health and safety requirement to minimise weight for lifting them out.