 At the I @-@ 380 interchange , I @-@ 80 becomes a six @-@ lane freeway . The Coral Ridge Avenue exit provides access to US 6 , which passes beneath the interstate just before the interchange , and the eponymous shopping center located to the southeast . The First Avenue exit in Coralville and Dubuque Street exit in Iowa City direct University of Iowa traffic to different parts of the university campus . The Iowa River flows between the two interchanges and also marks the boundary between Coralville and Iowa City . On Iowa City 's east side are the Iowa 1 and Herbert Hoover Highway exits . Between them , the highway drops back to four lanes and the speed limit increases to 70 mph ( 110 km / h ) . 
