I'm looking for implementations of approximation algorithms (or algorithms that would be meaningful to implement for use in practice) for the minimum-cost multicommodity flow problem as defined in e.g. Section 2.1 of
Andrew V. Goldberg, Jeffrey D. Oldham, Serge Plotkin & Cliff Stein An Implementation of a Combinatorial Approximation Algorithm for Minimum-Cost Multicommodity Flow, https://rd.springer.com/chapter/10.1007/3-540-69346-7_26
They give a description of an $(1+\epsilon)$-approximation algorithm in that paper and have implemented it as well, but the implementation does not appear to be readily available.
And is there any newer research/implementation that supersedes the 1998 work? There's certainly a good deal of work on various related problems such as maximum concurrent multicommodity flow, but that's not really what I'm after.