It is the intent of Johnson County to minimize the number of driveway entrances. All new driveway entrances must maintain a minimum of 500 feet separation, unless the County Engineer agrees to something less than 500 feet. Existing driveway entrances are exempt, provided they comply with #3. One entrance per residence or field. Entrances shall meet I.D.O.T minimum design speeds for sight distance. All rated @ 3.5 feet in height.
- 30 MPH - 200 feet
- 35 MPH - 250 feet
- 40 MPH - 305 feet
- 45 MPH - 360 feet
- 50 MPH - 425 feet
- 55 MPH - 495 feet
Culvert size is determined by drainage area. Metal culverts are being maintained by Secondary Roads at this time, landowners are responsible for all plastic and concrete pipe maintenance. The entrance, including drainage structure, grading and surface shall be constructed at the applicant’s expense. Extensions of entrance pipes must be of similar materials. No headwalls are allowed. Six (6) inches of fall must be maintained from the edge of road way to the centerline of the ditch. Maximum top width shall not exceed 40 feet measured over pipe. Paved entrances shall not have any curbs in the right-of-way. All entrances with a traffic count of 400-999 vehicles per day shall have side slopes of 6 feet horizontal to 1 foot vertical, with aprons. All entrances with a traffic count of 1000+ vehicles per day shall have side slopes of 8 feet horizontal to 1 foot vertical, with aprons. Entrances that do not require a culvert with 400+ vehicles per day shall be 8 feet horizontal to 1 foot vertical. Permits are good for one year from application date.