Here's my problem: I have a network of trails between locations scattered across the eastern US (think hiking trails, on foot, not vehicular travel).

I would like to calculate on-foot travel time (time unit doesn't matter-- seconds, minutes, hours, etc.) between individual locations using exclusively trails within that network.

  • I have a friction surface calculated from a base DEM (using Tobler's hiking function).

  • I may include waterways (I have this data from the NHD).

  • I know how to build a basic least-cost / cost-distance model, and how to set friction values for "desired" routes lower than the surrounding terrain.

What I don't know at this point is: How can I extract travel times from these data? Is that even possible within this type of calculation or from the products of such a model?

Note: I know that there is at least one "canned" solution that does something a little like this (the NPS has its "travel time cost surface model" toolbox).

The problem with the TTCSM is that it looks outward from a central point in all directions, based on a given time, and terminates the calculation once that "time" is reached in all directions.

I'm also not a fan of black box solutions, which the TTCSM definitely is. It works, but for what I'm doing, I need to know what's happening under the hood.

  • 2
    you're gonna have to give us some code that you're working with. Do you have vector data (eg shapefiles) of your trail network? It seems to me that if you've already got a friction surface then you could join those values to vector lines and sum over the lines in some fashion. – 0mn1 Jun 1 at 16:08

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