Land can approximately be converted to a recurring cost via rents.
Here’s one in Australia near Perth:
https://youtu.be/h8lhX9Q6Z5g?si=eloUWLcH8q3eJiZH
And I’m certain I’ve driven through other roundabouts with traffic lights in other states.
They work well when the peak-hour traffic tends to block some of the entrances. You can use the lights to allow the blocked entrances to flow, then turn the lights off out of peak-hour.