  Rail-guided vehicles (RGVs) are widely employed in automated freight handling
system (AFHS) to transport surging air cargo. Energy-efficient routing of such
vehicles is of great interest for both financial and environmental
sustainability. Given a multi-capacity RGV working on a linear track in AFHS,
we consider its optimal routing under two-sided loading/unloading (TSLU)
operations, in which energy consumption is minimized under conflict-avoidance
and time window constraints. The energy consumption takes account of
routing-dependent gross weight and dynamics of the RGV, and the
conflict-avoidance constraints ensure conflict-free transport service under
TSLU operations. The problem is formulated as a mixed-integer linear program,
and solved by incorporating valid inequalities that exploit structural
properties of the problem. The static problem model and solution approach are
then integrated with a rolling-horizon approach to solve the dynamic routing
problem where air cargo enters and departs from the system dynamically in time.
Simulation results suggest that the proposed strategy is able to route an RGV
to transport air cargo with an energy cost that is considerably lower than one
of the most commonly used heuristic methods implemented in current practice.
