“Toll tunnel” means the tunnel from U.S. Highway 50 in the vicinity of Twin Bridges to U.S. Highway 50 in the vicinity of Meyers which the authority is authorized to finance, construct, operate, and maintain as a toll facility pursuant to this chapter, and includes all appurtenances and additions, alterations or improvements thereto or replacements thereof, and the approaches to each end thereof, including any necessary connections with U.S. Highway 50, all lands and interest therein used therefor, and buildings and improvements thereon.