The upright looks like it has a couple line of site antennas and a power/network box probably. Looks like it is running/networking the device pointed downwards. That device likely has a series of sensors for detecting vehicle traffic. This setup helps track traffic for traffic control.
Context would help. General location (state, country, etc)? What kind of road? Were you near any other car infrastructure? Are the directionals pointing at anything informative?
I suspect the box facing down is some kind of short range antenna. Like for reading toll passes kind of thing, though I doubt this is that. The directionals first reminded me of like IR sensors for like emergency vehicle signalling, but you'd normally see that on a traffic light.
Can't find an exact one, but here's an interesting example of a traffic detector:
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And in the road there would be a buried paired receiver. And it would detect if a vehicle blocked the signal between the two.
it was on a street light after an intersection, in California. from the comments it would make sense to be for traffic control. My original thought was a gunshot detector since I remember hearing they installed them in the city but doesnt seem that this is it