  We study the hydrodynamics of the hard rod model proposed by Boldrighini,
Dobrushin and Soukhov by describing the displacement of each quasiparticle with
respect to the corresponding ideal gas particle as a height difference in a
related field. Starting with a family of nonhomogeneous Poisson processes
contained in the position-velocity-length space $\mathbb{R}^3$, we show laws of
large numbers for the quasiparticle positions and the length fields, and the
joint convergence of the quasiparticle fluctuations to a Levy Chentsov field.
We allow variable rod lengths, including negative lengths.
