Does anyone know the name for graphs like "Station Fullness Over Time of Day" is? I don't remember having seen one before (I don't look at many graphs) but fin

Does anyone know the name for graphs like "Station Fullness Over Time of Day" is? I don't remember having seen one before (I don't look at many graphs) but find it incredibly readable, even being color deficient. Also, can't say I dug further than the homepage, but it was striking enough for me to ask.