1 Erratum to: 4OR-Q J Oper Res (2014) 12:359–372 DOI 10.1007/s10288-014-0260-9

In Bostel et al. (2014), we developed simple and easy-to-use approximation formulae for the length of a Chinese Postman Problem (CPP) optimal tour on directed or undirected strongly connected planar graphs as a function of the number of nodes and the number of arcs of graphs whose nodes are randomly distributed on a square area.

These approximations have been obtained from a multi-linear regression analysis, by randomly generating a large number of graphs on a square area of \(100 \times 100\) and determining the optimal tour lengths, and not on a unit square area as indicated erroneously in the article. As a consequence, for the general case of graphs extended over a square region of surface area A, the approximate lengths of optimal tours provided by our formulae have to be multiplied by \(\frac{\sqrt{\hbox {A}}}{100}\), and not by \(\sqrt{A}\) as indicated in the article.