How can I get into an operations research career in the construction industry?

This is a great way to ask this question. Operations research is another term for supply chain management. Michigan State and Penn State universities are the top SCM schools in the U.S. and can be reasonably manageable to get into, especially for an engineer like you! I am a fan of both schools for various reasons, and I am an alumna of PSU's program. If I were looking to focus in construction, I would target MSU. I do not know of universities that focus directly in construction science, but Google does. I don't see a problem to solve, in your question. I see you already well prepared and doing all the things that one can do in these situations. Internships are the easiest ways to pipeline oneself into one's career of choice as a young person who has access to formal education. We integrate our interests with our disciplines by wanting to, not by there being a path. Just because we old people haven't started something already that combines the exact ways you will combine disciplines, has nothing to do with you not being able to do so. Most of my awards are in areas that I was not even hired to serve in - but my project won them because I will ALWAYS create one solution correctly the first time, no matter how siloed anyone else's thinking is.

Something I've often harped on in giving advice is that all fields of knowledge overlap in some way. And I've also frequently mentioned that the way to get into some field is to simply do it. That is, get in touch with companies and organizations in the construction industry and offer to help them with whatever they need. Get into an internship or co-op program. You may not start out with exactly what you're interested in, but in general, if you want to get "into" something, you go to where that "something" is happening. And if you contribute to a project somehow, you'll gain leverage and connections. As time goes on, you'll be able to tailor your assignments to exactly what you want to do.

Your statements about STEM are right on. In general, anything you choose to do will benefit from that sort of training. Many corporations have connections with universities both to access talent in their needed positions as well as to cultivate prospective employees for the future. You can take advantage of this and actively contact counselors and teachers who can help you along the way. The basic idea is just like going where the "something" you want to get into is, if you want to do anything, find people who do it. They can point you to opportunities. A side benefit is that once involved with people who are active in what you want to do is that you can refine your goals to see if it's real match. Or to get into more details on what to expect and what to plan for success.

The key here is perseverance. You may find dozens of people who simply don't need your help. But it only takes one who does. And that person might have friends and other contacts. The cool part is that you'll be making progress finding out exactly what you want to do and having fun along the way.