Default file name and path
The travel time matrix (skim matrix) does not have a default name, but has to be defined by the property: auto.peak.skim.YYYY where YYYY is a year. In general, at lease a matrix for the base year is required (Exceptions are settings using MATSim as transport model and re-constructing travel times from a MATSim simulation by reading a MATSim event files).
Description
The travel time matrix is a matrix where each cell shows the travel time from a certain origin (row) to a certain destination (column).
The travel time matrix is stroed in an OMX file. OMX files store a set of matrices of same dimensions into a single file. Documentation and APIs for different languages are found in https://github.com/osPlanning. Each matrix stored within an OMX has a name. The travel times by car are stored in a matrix called, by default, "travelTimeAuto". This can be canged by the property auto.peak.sov.skim.matrix.name.
Additionally, OMX files have a lookup vector, which, for each zone id (called externalId), gives the index of the matrix (called internalId). This is important if zones are not numbered as 1,2,3,...N but use ids that start at a higher number (e.g. 1001, 1002, 1003,...) or skip certain values in the range (i.e. 1,2,4,7,10,... N). If the matrix has dimensions nxn, the lookup value is a vector of n elements where the values are the IDs of the zones.
Data Source
The travel time by car matrix of Munich was obtained using MATSim. Travel time is queried from one (or more) point(s) of each origin to each destination and stored accordingly.
Example
You can download an example of Munich matrix from: https://github.com/msmobility/silo/blob/master/useCases/munich/test/muc/skims/skimsAllIntrazonal.omx