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Map zoom/rendering oddity

16 Dec 2017
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I was contemplating routes between the Chester area & the Camping & Caravan Club site NW of Bala and encountered the following.

I found it on the A5 west of Corwen, between Maerdy & Dinmael (I've no idea if it occurs elsewhere). If I view the map so the little scale bar in the top right corner of the map says 1000ft there is a minor road shown leading NE from near Maerdy, just North of the A5, joining up with other minor roads passing N of Dinmael. If I zoom in one level (500ft on the scale bar) that minor road disappears from view, only to reappear when the map is zoomed in again (300ft). will quite happily route along the road at the "500ft" zoom even though it isn't visible so it "knows" it is there. Is it simply a rendering problem? Or a mapping problem with that particular minor road?


Sun 17 Dec 2017, 09:32

It'll be a caching issue. asks your browser to remember its map tiles for quite a long while, so that you can pan along a route to get all the map tiles in the cache, then set out on a ride and hopefully still have them in the cache without having to download them (which can be tricky in areas of poor phone reception). So in this case I guess the road has only recently been added to OpenStreetMap – unusual in the UK, but certainly not unheard of in mid-Wales – and your browser is remembering the previous version.

If you zoom to the place/zoom where it’s missing, click ‘Link to this place’ in the bottom right to anchor the URL to the current location, then shift-refresh to force everything to be pulled down from the server again, hopefully it should get the latest tiles.