Then how can a speed limit reduction on a 4 lane road be legally enforced? I know on the 400 series roads they always sign on both sides during construction, I have to assume they do it there to meet some law/rule!!

Have gone through HTA and R.R.O. 1990, Reg. 615: SIGNS and cannot find the info I'm looking for. My question is this, when on a four lane divided highway (two lanes each direction with a Median) do speed limit signs need to be posted on the left (in median) also? I can be in the left lane, with a tr...