306.9  Diagonal roads — restoring and improving existing roads.
  It is the policy of the state of Iowa that relocation of primary highways through cultivated land shall be avoided to the maximum extent possible. When the volume of traffic for which the road is designed or other conditions, including designation as part of the network of commercial and industrial highways, require relocation, diagonal routes shall be avoided if feasible and prudent alternatives consistent with efficient movement of traffic exist.
  The improvement of two-lane roads shall utilize the existing right-of-way unless alignment or other conditions, including designation as part of the network of commercial and industrial highways, make changes imperative, and when a two-lane road is expanded to a four-lane road, the normal procedure shall be that the additional right-of-way be contiguous to the existing right-of-way unless relocated for compelling reasons, including the need to provide efficient movement of traffic on the network of commercial and industrial highways. This policy does not apply to a highway project for which the corridor has been approved by the state department of transportation and the corridor has been finalized by September 1, 1977.
  It is the policy of the state of Iowa that in constructing primary highways designed with four-lane divided roadways, access controls shall be limited to the minimum level necessary, as determined by the department, to ensure the safe and efficient movement of traffic or to comply with federal aid requirements.
  Unless otherwise required by the federal law or regulation, it is also the policy of this state that road use tax fund moneys shall be used to rehabilitate or reconstruct existing roads, streets, and bridges using substantially existing right-of-way. This paragraph does not apply where additional right-of-way is needed for the construction or completion of designated interstate or city routes and highway bypasses or highways designated as part of the network of commercial and industrial highways.
[C79, 81, §306.9; 81 Acts 2d Ex, ch 2, §1]
83 Acts, ch 198, §14; 89 Acts, ch 134, §2; 98 Acts, ch 1075, §6