A railroad yard boss makes friends with a young hobo and then puts his relationship with the woman he loves in jeopardy.
Starring Louis Wolheim, Jean Arthur, and Robert Armstrong.
Directed by George B. Seitz.
Story by James Ashmore Creelman.
Originally, Danger Lights was registered with a copyright date of December 5, 1930, by RKO Productions, Inc. However, according to US copyright records, there was no formal copyright renewal in 1958 per the law at the time. Therefore, I believe that Danger Lights has become public domain.
Archive.org also lists this movie as public domain with creative commons attributes.