Signage can be a pretty significant cost, do your research to find out what you need legally and but quality.
Here in Ontario we are dictated by the provincial government as to what signs are reguired, what size and colour they are and where to place them on a job site.
Not uncommon to spend 2-4K on signage to avoid issues and legalities.
We had a situation a few years ago doing some roadside work along a busy 4 lane road that involved shutting down one lane. I had actually taken pictures earlies that day of the job that showed most of our signage. Later on a guy driving by was rubbernecking the operation and piled his Mustang into the back of another vehicle that had stopped to make a left hand turn. He claimed later that our signage was not appropriate to the job and that he had not been sufficiently warned of the lane closure.
If not for my photo and our job site tailboard that listed the signage used we could have been facing a legal battle.
Sent copies to his lawyer, end of issue.