These climate-based arguments for why we should maintain cities primarily designed around the car are just... dumb. Don't fall victim to them. There is only one effective way to reduce congestion long-term and that is reducing the need for cars. Creating streets that are safe and pleasant for people outside of cars promotes alternatives to driving. And in doing all of this, you'll have a huge impact on the climate instead of a worthless marginal one.
Road user cost is an EXTREMELY well-studied field with hundreds of complete manuals and textbooks written on the subject. Most states have their own full guidelines. You can very, very directly quantify what the impact of things like work zones is in terms of dollar figures based on theoretical impacts to travelers. So yeah, in those terms, the DOT does put a dollar value on congestion, absolutely. Just as the EPA creates a metric for putting a dollar value on a human life when analyzing impacts of pollution.
The actual traffic study for this would be comparing an intersection with ROR AB tested to without ROR, modeling the increased delay for drivers, and translating that into a figure. A minute or two delay... actually doesn't amount to very much, and that's what a typical case would be of forcing a driver to wait an additional cycle. Not to mention that, in a world without ROR, there is no a very good reason to force engineers to do their fucking jobs and design the intersection to work better without that dangerous crutch.
The Philadelphia paper is the seminal work on all way stops being safer than signals in urban contexts. It is pretty definitive and similar studies have confirmed the results, cementing them into most complete streets design guides.
Studies on roundabouts being safer are... even more conclusive and abundant. I really can't cite just one because damn, there's so damn many.