16 Pa. Stat. § 5727
Where county bridges have been or shall hereafter be destroyed or rendered impassable by fire, storm, flood or other casualty, the county commissioners may provide, at the expense of the county, ferries or other temporary ways as a substitute for such destroyed or impassable bridges, until such county bridges shall be rebuilt or rendered fit for public travel. Where a county bridge spans a stream which is the boundary between two counties of this Commonwealth and the bridge across such stream has been built and maintained at the joint expense of said adjoining counties, the establishment and maintenance of such ferry or temporary way shall be by the joint discretionary action of the boards of commissioners of said counties and the expense thereof shall be borne by said counties in equal share.
16 P.S. § 5727