The paper deals with nonlinear multicommodity flow problems with conve
x costs. A decomposition method is proposed to solve them. The approac
h applies a potential reduction algorithm to solve the master problem
approximately and a column generation technique to define a sequence o
f primal linear programming problems. Each subproblem consists of find
ing a minimum cost flow between an origin and a destination node in an
uncapacited network, It is thus formulated as a shortest path problem
and solved with Dijkstra's d-heap algorithm. An implementation is des
cribed that takes full advantage of the supersparsity of the network i
n the linear algebra operations. Computational results show the effici
ency of this approach on well-known nondifferentiable problems and als
o large scale randomly generated problems (up to 1000 arcs and 5000 co
mmodities).