Routing breaks near severances without separately mapped footways

https://www.openstreetmap.org/way/997182611 and nearby -- can't cross at all, so score layer is empty there.

The problem is that we're not walking _along_ Church road, which has sidewalk=both. Methodology really depends on separate footway tagging. We could handle walking along a tagged sidewalk, but we'd need to start tracking side of the road. Alternatively, we could try to automatically generate footways along the main road.