I was recently watching an old TV show whose opening included a shot of the predecessor of this BGS (https://www.google.com/maps/place/Hollywood+Hills,+Los+Angeles,+CA/@34.1234635,-118.342289,3a,75y,128.51h,80.61t/data=!3m4!1e1!3m2!1sWMMztth65DSCYAP927ZUKQ!2e0!4m2!3m1!1s0x80c2befcd4adeec7:0xf125a5a70e9860c2) on the southbound Hollywood Freeway from the early 1980's. Across the top of the mainline pull-through there was a row of black text on yellow background that read "NIGHT WORK AHEAD WHEN FLASHING". Above it had been installed two yellow flashers.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FeIA0vN5.jpg&hash=71818846c2399102dcb01f0ff4dc74d3eeeff3bd)
Does anyone remember this sign and know what the night work was on the freeway that prompted a semi-permanent sign installation on an existing BGS?