a train track with weights, or weighted train track or measured train track, consists of a train track with a non-negative real number, called a "weight", assigned to each branch. the weights can be used to model which of the curves in a parallel family of curves from a lamination are split to which sides of the switch. weights must satisfy the following switch condition: the weight assigned to the ingoing branch at a switch should equal the sum of the weights assigned to the branches outgoing from that switch.