 Most interchanges were to be located near population centers; an option to build a seventeenth near Grinnell, if necessary, was included.Eight service areas, similar in quality to those found on the Pennsylvania and New Jersey turnpikes, were planned as well.On April 29, 1955, an enabling act, which created the Iowa Toll Road Authority, came into effect giving the Authority the power to further study the feasibility of building a turnpike across the state.