I am certain that talking about decibels will only lead to problems.
Mr. Jeanes mentioned that noise from a railway often has peaks. It can go from 0 to 100 decibels and then right back to 0 decibels. It is intermittent. Moreover, the noise coming from the Queensway here in Ottawa is at a constant 100 decibels from a distance of just one or two houses away. It is a constant background noise.
Thus, if we were to indicate an unvarnished decibel limit, this would cause serious problems. However, if we said that, in cases of complaints and so on, the board must investigate and, based on the facts, do as you suggest and adopt an approach by which it “must” set guidelines, and not just that it “can” set guidelines, then the answer is yes.