When preparing geodata for smaller scales, you need generalisation algorithms. Douglas-Peucker and Visvalingam-Whyatt algorithms are usually used for lines (polygons). Unfortunately those are mathematical/geometrical algorithms which do not take into account cartographic requirements.

Wang–Müller algorithm tries to do exactly that - generalise lines (of natural objects) according to cartographic requirements, such as saving or even exaggerating characteristic features.

Original Wang–Müller article has a quite concise description of the algorithm and as there is no open source implementation of this algorithm (to my knowledge) it is impossible to use this algorithm in wider scale and there are a number of unanswered questions on how some particular aspects should work.

A student of Vilnius University, Motiejus Jakštys, has done a perfect job - he has not only implemented the main part of Wang–Müller algorithm using open technologies, but also described the algorithm in his paper, which you can find here:

https://github.com/motiejus/wm/blob/main/mj-msc-full.pdf

Besides describing the algorithm itself (in more detail that original paper), this paper also includes recommendations on values of parameters to use on different scales, a lot of pictures as well as propositions for future work on finishing and refining the open implementation.

In coming days the work of Motiejus will be forked into Lithuanian Openmap repository where work on this algorithm will be continued and we hope to have a final implementation some time this year.