§ 23. Highway exempted. No railroad shall be constructed, maintained or operated and no railroad tracks shall be laid upon the state road known as the Buffalo and White's Corners plank-road in the county of Erie, where none now exists, excepting such as may be necessarily laid for the purpose only of crossing said highway. The provisions of this section shall not affect any consents granted prior to the eighteenth day of April, nineteen hundred and five, or any rights acquired for the construction of any such railroad.