Shrink the directional way markers slightly

[bhousel]

I would suggest these be much subtler. In particular, guard rails are placed along the roads, which means they will run parallel to the road and the arrows will point at the road. In practice, this means they overlap (some here are in the wrong direction):

Here's a more zoomed-in example, which would be a typical "editing zoom":

I would say the arrows should be no more than half the current size and without a gap between the line.

Originally posted by @RudyTheDev in #5529 (comment)

[huonw]

The reason for the gap is that I couldn't get the version without a gap to look good at all, due to the dashed line. For it to look good, I think the triangles would at least need to be synchronised to the dashes e.g. always attached to the middle of the long section. (It'd be awesome if someone more skilled in the ways of SVG/CSS/D3 could work out how to do this reliably, I couldn't!)

Making them smaller should be simple enough, though. (I don't think I'll personally have time to do anything towards it until at least next week.)

(See also #1475 (comment) for another request for things to be subtler, at least for barrier=kerb.)

[jguthrie100]

@huonw i've never worked with SVG before, but it should be as simple as working out the length of the repeating pattern of the dashed line and just scaling the arrow SVG so it repeats at the same frequency!

[huonw]

I tried that but I rejected it because I think the initial offset was different for different lines, meaning the arrows ended up in different spots on different ways, including overlapping the gaps sometimes. (That iteration was a few months ago so I may be misremembering.)

[bhousel]

I made them half the height that they were before, and it seems a little better: