When does Mighty Express return?

The series takes place in Tracksville, a town located in a reality where human adults (with the exception of Santa Claus) have never existed and where kids run the stations and other locations and work together with the Mighty Express trains. The series follows the adventures of eight trains each with a different purpose and skill. Unlike the previous six seasons, which all had ten-minute-long episodes, the seventh has a double-length episode and two compilation episodes featuring the shorts.