An infinite Bernoulli-Euler beam (representing the “combined rail” consisting
of the rail and longitudinal sleeper) mounted on periodic flexible point supports
(representing the railpads) has already proven to be a suitable mathematical
model for the floating ladder track (FLT), to define its natural vibrations and its
forced response due to a moving load. Adopting deliberately conservative parameters
for the existing FLT design, we present further results for the response to a
steadily (uniformly) moving load when the periodic supports are assumed to be
elastic, and then introduce the mass and viscous damping of the periodic supports.
Typical support damping significantly moderates the resulting steady deflexion at
any load speed, and in particular substantially reduces the magnitude of the resonant
response at the critical speed. The linear mathematical analysis is then extended
to include the inertia of the load that otherwise moves uniformly along the
beam, generating overstability at supercritical speeds — i.e. at load speeds notably
above the critical speed predicted for the resonant response when the load inertia
is neglected. Neither the resonance nor the overstability should prevent the safe
implementation of the FLT design in modern high speed rail systems.