system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does America mostly use traffic lights at intersections when Europe uses a lot of traffic circles? What are the benefits to either?

My university recently removed a traffic circle in favor of traffic lights. It probably cost a bunch of money because they had to rebuild to whole intersection so it was a traffic light instead of a circle.

What are the benefits to either? Why would they change something that seemingly worked in favor of something that takes twice as long to get through.
gpt
A roundabout (or traffic circle) can usually handle a greater volume of traffic. It's relatively rare, at least outside of the rush hour, for traffic to come to a complete standstill, which is the case with traffic lights. However, roundabouts do force traffic to slow down: at traffic lights, drivers may be tempted to speed through a green light, but at a roundabout you have to slow down. So you have this twin benefit of traffic that slows down (which is safer) but flows more smoothly (which is quicker). Also, while at a standard intersection you have to watch for traffic coming from several different directions, at a roundabout you only need to worry about traffic coming from one direction (from the left in countries that drive on the right, and vice versa).

But there are downsides. First of all, if you have an intersection where lots of pedestrians are likely to be milling around, traffic lights can be programmed to allow pedestrians to cross safely. This isn't possible with roundabouts, where foot bridges or foot tunnels become necessary unless you want to put in crossings on every road just before the roundabout, completely negating most of the advantages. Also, roundabouts can actually become choked at times, and while traffic lights can be programmed to take account of this, roundabouts can't be regulated in this way. Roundabouts also need more space, especially where large trucks and other vehicles have to use them.