num
How many vehicles were stopped mid-route for want of charge when the replication ended.
Written for every replication, zero included, so the across-replication average is the mean number stranded per run rather than a mean over the runs that went wrong. A figure that is not zero says the fleet's charging policy does not work at this demand, and every other statistic in the run was measured on a layout that was quietly missing some of its aisles.