In memory

I'm seeing more and more of these roadside memorials. Some come and go within days of a tragic accident but there many that persist for far longer. This one near where I live has been maintained for months. There are places in the UK where they have caused problems but their increasing frequency suggests they are becoming more tolerated. The policies of some local authorities suggests they are getting more tolerant too.
This site lists more than 500 of them in Ireland. There is a register for UK roadside memorials here but it's not very well maintained.

Most of the ones I'm seeing, and I'll try to photograph them when I can, are for traffic accidents. But they have a long history. In Ireland they commemorate where people died during the war of independence and the civil war. I know I've seen them in France and Italy too.

There's research being done into these spontaneous shrines. I didn't know it but there are also "ghost bikes" - bikes painted white that are attached to a spot where a cyclist was knocked down or killed.

I suppose I'm slightly puzzled as to why they mourners set them up and maintain them. I can understand it in a graveyard as that's where the remains are laid to rest. But at the place a person died? Is it because they died there, at that spot? I'd guess that relatives would pass by the spot regularly too. Do they genuflect? Is it so they don't forget, that they have to remember, when there is a danger that they would forget?