Long, Leader
The long radical and the long kanji are the same! This kanji also means leader, because the longer a person is, the better a leader they'll be. Or maybe it was... the longer they've been somewhere? Whatever, longness = leaderness, you know?
As long as you know the radical long, you know the kanji long as well.
ちょう
なが
は
You see a very long person. It's Mrs. Chou (ちょう), who has made herself long, like her street. "I made myself long so I can watch more of the street, my domain. I'm the leader of these streets. Watch yourself not-long person," says Mrs. Chou.
Long isn't an idea that's easy to imagine in any specific sense, but you can try some other things too, as long as it gets associated with Mrs. Chou. For the most part, when you see a kanji with the radical 長 the reading will be ちょう.