This paper shows that the FPTAS for the min-max disjoint paths problem on directed acyclic graphs by Yu et al. (2010)  can be improved by a rounding and searching technique. © 2010 Elsevier Inc.
Wu, B. Y. (2011). A note on approximating the min-max vertex disjoint paths on directed acyclic graphs. Journal of Computer and System Sciences, 77(6), 1054–1057. https://doi.org/10.1016/j.jcss.2010.08.012