shows the quantitative relationship between sources and sinks, i.e. the number of transport or mass units moved per time unit. The total quantities in the output or input are calculated by summing the columns and rows.
If there are predominantly individual, fixed source-sink relationships, this is also referred to as unidirectional transportation; if, on the other hand, many sources are connected to many sinks, this is referred to as multidirectional transportation. This can be an important feature – in conjunction with the transportation distance matrix – for the selection of a transportation system.

Source: logipedia / Fraunhofer IML