  Traffic flow of athletes in classic-style cross-country ski marathons, with
the Swedish Vasaloppet as prominent example, represents a non-vehicular system
of driven particles with many properties of vehicular traffic flow such as
unidirectional movement, the existence of lanes, and, moreover, severe traffic
jams. We propose a microscopic acceleration and track-changing model taking
into account different fitness levels, gradients, and interactions between the
athletes in all traffic situations. The model is calibrated on microscopic data
of the $\textit{Vasaloppet 2012}$ Using the multi-model open-source simulator
MovSim.org, we simulate all 15 000 participants of the Vasaloppet during the
first ten kilometers.
