https://www.thedrive.com/news/how-an-artist-helped-millions-...

> And then…nothing. Caltrans didn’t notice. Passing motorists were thrilled but figured the improvement had taken place at the direction of Caltrans. It wasn’t until Ankrom leaked his actions to the press that the true story was known.

> The original sign with Ankrom’s artwork remained until 2009 when the whole thing was replaced by Caltrans. The paint had faded, but the message remained with a lasting impact. The replacement sign erected by the Department of Transportation proudly sports the 5 North placard exactly where Ankrom had put it nearly a decade prior, and it remains there to this day to help motorists that would otherwise be just as confused as he was.

And an update from 2023:

> In 2001, artist Richard Ankrom posted a "5 North" sign on the 110 N. in DTLA to alert drivers to get in the left lane for the 5 turnoff. His work was so impeccable (and helpful), Caltrans at first didn't notice, then allowed it to stay. "5 North" is now part of permanent signage.

The short film he and his friends made about the process is definitely worth a watch: https://youtu.be/Clgl63CWOkM