(a) Whenever authorized signs are erected indicating that any street or part thereof is a play street, no person shall drive a vehicle upon any such street or portion thereof except drivers of vehicles having business or whose residences are within such closed area and then such drivers shall exercise the greatest care in driving upon any such street or portion thereof.
(b) Whoever violates any provision of this section is guilty of a minor misdemeanor on a first offense; on a second offense within one year after the first offense, the person is guilty of a misdemeanor of the fourth degree; on each subsequent offense within one year after the first offense, the person is guilty of a misdemeanor of the third degree.