netconvert --matsim myMATsimNetwork.xml -o mySUMOnetwork.net.xml
MATsim does not work with the lane numbers of streets, instead, the streets' capacities are used. This means that under circumstances the information about the edges' lane numbers are missing. The importer tries to determine the lane number from the given edges' capacities using:
LANE_NUMBER = MAXIMUM_FLOW / CAPACITY_NORM
The value of CAPACITY_NORM is controlled via the option --capacity-norm <FLOAT> (default: 1800).