  A version of a conjecture of McMullen is as follows: Given a hyperbolizable
3-manifold M with incompressible boundary, there exists a uniform constant K
such that if N is a hyperbolic 3-manifold homeomorphic to the interior of M,
then the injectivity radius based at points in the convex core of N is bounded
above by K. This conjecture suggests that convex cores are uniformly congested.
We will give a proof in the case when M is an I-bundle over a closed surface,
taking into account the possibility of cusps.
