Hello!
To provide some background, I am using ORS with QGIS for a thesis in the context of assessing access in rural Africa and it’s been super helpful so far! 
After calculating walking time catchments (30, 60, 120min) to certain services, I was interested in conducting a sensitivity analysis of sorts by varying speed assumptions by +/- 20% to see how assumed travel times would vary in this case as a result.
Based on some digging on this forum however this seems more challenging than I first imagine - is this the case or am I missing something? As a newbie to the world of GIS and ORS, I haven’t gone too deep into the clockwork that’s behind the user interface so that would be uncharted territory for me.
Any tips or feedback here would be appreciated!
Hey,
out of the blue, you could just calculate new walking times for all your segments or the whole route, using a factor of 0.8-1.2 and see a change, although that would not change the routes themselves.
I assume you want to change walking speeds and see if and how the routes change.
I don’t think that will happen, if your routes are not going over paths with an sac-scale > T1. You would change all segment’s lengths by the same factor, so nothing should change since shortest paths before are shortest paths after either way. This might change if you have additional constraints, though.
If you still want to try, I think the easiest thing to do would be to set up ors for yourself and then change the hardcoded speed values for the walking profile. The backend documentation should contain all info on how to do that.
Best regards