A few years back, they did some major work on a highway near me up here in Canada. What I did was note which company was doing the work. It was written on their trucks. I looked the company up in the Canadian TAFL database and found they had several analog VHF frequencies licensed to them.
By scanning these, I found the truck frequencies and I also managed to locate the flagmen who were directing traffic where one lane was serving traffic going in two directions.
If there is a similar FCC lookup showing frequencies by company, you might try there..