“ It was the clear pronouncement of the Pennsylvania courts that the state statute provides a complete procedure to guar an d protect the plaintiffs' constitutional rights 'at all times.' In the light of this pronouncement it is difficult to perceive the basis for the District Court's conclusion that the plaintiffs would be irreparably harmed unless the state officers were enjoined from proceeding under the statute. There is no question here of the State's right to create or designate a limited access highway. The only question is the plaintiffs' right to compensation. ”

“ Reflected among the concerns which have traditionally counseled a federal court to stay its hand are the desirability of avoiding unseemly conflict between two sovereignties, the unnecessary impairment of state functions, and the premature determination of constitutional questions. ”

“ There is no reason to suppose that the Commonwealth of Pennsylvania will not accord full constitutional scope to the statutory phrase 'actual taking of property.' [5] If, after all is said and done in the Pennsylvania courts, any of the plaintiffs believe that the Commonwealth has deprived them of their property without due process of law, this Court will be here. ”