 The speed limit on the newly completed stretch is the highest in the United States at .State Highway 45 is part of an eventual partial loop that runs east from U.S. Highway 183 in Cedar Park to State Highway 130 at Pflugerville (east of Round Rock) where it merges with the SH 130 toll road, and then intersects with the southern portion of SH 45 near Buda, south of Austin.SH 45 is one of the very few East/West connectors in Austin, but it also connects to a tolled extension of Loop 1 (also known locally as the "Mopac Expressway") and allows direct access from to I-35 to Loop 1 by use of flyover connections rather than ground level intersections.