  In this article, we compute the pseudo-effective cones of various projective
bundles $\mathbb{P}_X(E)$ over higher dimensional varieties $X$ under some
assumptions on $X$ as well as on the vector bundle $E$. We also compute the
volume function on fibre product $\mathbb{P}(E)\times_C\mathbb{P}(F)$ of two
projective bundles over a smooth irreducible complex projective curve $C$. In
particular, we show that the volume function on the fiber product of two ruled
surfaces is of polynomial type.
