It appears that there may not be a state code covering this, but local ordinances DO seem to be common AND they pass Constitutional muster.
See this appeal where there is ample discussion of these ordinances:
http://www.courts.state.pa.us/OpPost.../A06018_05.pdf
Even without signs or notices, the section can be upheld. If the ordinance does mirror some state law in this area, then you are doubly damned as you are presumed to know your state's traffic code when you accept the responsibility to drive ... yeah, I know there is no way to know EVERY rule, but the expectation is there all the same.
- Carl

