Feature request: option to keep summary information about origins and destinations associated with each link

Use case: you want to know the main areas that will benefit from investment in a particular bridge. Illustration for Waterloo Bridge:


This suggests that many of the users are coming from the south of the river to access destinations just north of the river.

I recall conversations at FOSS4G last year in Florence about ways to do this on-the-fly, that was impressive. In this case it's just returning all the routes that intersect with the view area after zooming in and clicking 'Free lines'. Not the most intuitive interface or efficient implementation, but works to illustrate the concept.

Source: https://www.pct.bike/m/?r=london