What school on what road? Almost all olentangy schools in delaware county are located along 45 mph roads.
Some, as you mentioned, just say "20 MPH during restricted hours". and do not include a time zone. Others do.
According to ODOTs website, theyre adding turn lanes on 315 at powell road in both directions. Supposed to be completed by the end of fall, but i highly doubt that, as construction hasnt even begun.