What the hell is this?

[pderocco]

https://maps.app.goo.gl/fm6FuSYmbaLmY6cF8

This is where US-30-BYP joins US-30/I-84 east of Portland OR. In the latest GSV imagery, but not in any earlier imagery, is this strange sign that says route 43 on it, which is miles away. It has three other metal blanks on it, which you can see are blank on the other side if you turn right onto the on-ramp and look back. It also seems odd that it's screwed to the sidewalk, rather than being driven into the earth. Looks like an ODOT sign, though.

[Bickendan]

It's a detour assembly for I-84 eastbound that's not needed at that specific moment, so it's turned to face away from 238th Dr. Once the eastbound onramp needs to close, the assembly will be rotated.
That OR 43 shield has the I-84 (non-cutout) shield on the reverse. ODOT's simply using both sides of the 2 digit shield blank, and I suspect it's one of the reasons ODOT no longer uses cutouts for the Route or US shields (while generally only using non-cutout Interstate shields in instances like this).

[xonhulu]

Bickendan's right.  If you navigate down the on-ramp in your image, turn around and zoom in, you can see the back side of your sign:

https://maps.app.goo.gl/J7bnnBZ37qxjyPeP9

This is a pretty common practice for detour signage in Oregon, when the road closures are ongoing & intermittent because work is only done nights/weekends/other selected times.

[pderocco]

I see. So they show up with a little wrench, remove the nuts, turn the sign 90 degrees, put the nuts back, and then go to work? Sounds reasonable. Thanks for the quick answer.

[74/171FAN]

I have seen this in Akron, OH, before since that place is under constant construction since at least my clinch of the western I-76 in February 2019.

[epzik8]

Maryland makes heavy use of this practice as well, especially during the summer roadwork season.