Is is possible to grow a buffer around a feature, except where another feature stops the expansion using QGIS?
There is an existing similar question for ArcGIS Desktop: Buffering with physical barrier using ArcGIS Desktop?
My concrete task is finding cycleways suitable for children, where one criterium is "not dangerously close to major road". I can do this with a buffer around major roads, and removing cycleways within this buffer. However, if some suitable barrier exists, I would like the buffer/"danger zone" to stop there.
Simply making another buffer around the barrier and subtracting from the "danger zone" buffer around the road won't do, as that could also erroneously remove cycleways on the "dangerous" size of the barrier from the "danger zone". I was thinking of somehow finding which is the "safe side" of a barrier, and make a "safe zone" feature from that to cut from the "danger zone" buffer.