I recently launched a campaign against sexist roadside construction signs in Los Angeles, including ways to take action (there were a lot of mixed reviews on this topic).
I have to say, the bureaucratic process worked wonders this time around; I was contacted by the Women's Advocate of the City of Los Angeles Human Services Department, who looked into my concern.
The findings? The federal government went gender-neutral with signs in 1988 and the State of California in 1996. In short, "Men Working Ahead" signs are illegal and can be reported.
If you live in Los Angeles and see these signs on city construction sites, please report them to Seffy Wiles of the LA Bureau of Public Works at (213) 487-2408.