It's rush-hour-only service. He's using the notation from the official map [1], but I think he forgot to put it in the key.
[1] https://upload.wikimedia.org/wikipedia/commons/3/3a/Official...
[1] https://upload.wikimedia.org/wikipedia/commons/3/3a/Official...
And by the way, for his legal case, if there was anything to point to the argument of derivative work, this would be it. It's clearly copying (because it's so confusing) the broken line segments style in the map you just linked.
For example, here it is on a philly trolley map: https://www.septa.org/maps/trolley/city.html
And you can also see the same sort of thing on this BART map: https://www.bart.gov/system-map