(A) The arrangements, character, extent, width, grade, and location of all streets shall conform to this chapter, and any standard specifications and drawings adopted by the Commission, and shall be constructed in relation to existing and planned streets, to topographical conditions, to public convenience and safety, and in their relation to the proposed uses of the land to be served by such streets.
(B) All roads to be accepted and maintained by the county shall be designed in compliance with the standards outlined below. (See § 152.076 for private roads).
(C) Roads shall be considered in two categories:
(1) Local roads: 0 – 250 average daily traffic (ADT); and
(2) Collector roads: 250 – 00 ADT.
(D) The Design Engineer shall specify the ADT and the traffic speed that is to be expected when the subdivision is fully developed.
(E) Local or minor residential streets shall be designed as to discourage their use by through traffic. Streets shall be considered local if the average daily traffic is 250 or less.
(F) Where a subdivision abuts or contains an existing or proposed arterial street, railroad, or limited access highway, the county may require frontage streets, reverse frontage streets, or such other treatment for the appropriate use of the tract.
(G) There shall be provided rights-of-way of such width and as provided for in this chapter, and standard specifications and drawings adopted by the Commission; provided, however, that the width of said right-of-way shall in no case be less than the following.
Type of Street | Right-of-Way Widths |
Arterial | 80 feet |
Collector | 60 feet |
Local | 60 feet |
(H) Cul-de-sac streets shall terminate in a circular turnaround with a right-of-way radius of at least 50 feet with a surfaced turn around of a 45-foot radius. The Commission may approve an equally convenient form of turning space where extreme conditions justify. The maximum length shall be 1,000 feet from the entrance to the center of a turnaround.
(I) The right-of-way width, slope easements, cut and fill slopes, ditches, gravel depth requirements, and the like shall comply with Figure 1. Note: asphalt surface only required on subdivisions with lots less than one acre. See § 152.075(E).
(J) Special soil conditions may warrant additional ballast or other treatment so as to assure a stable road bed. The Design Engineer shall prepare a report certifying the adequacy of design, particularly in areas of concern based on U.S. Soil Conservation Service soil studies.
(K) Dead-end streets will not be approved except in locations designated by the Commission as necessary to provide for future extensions in development of adjacent lands. In any case, a dead-end street serving more than four lots shall provide by easement a temporary turning circle with a 50-foot radius or other acceptable design to accomplish adequate access.
(L) Streets shall be planned to intersect at 90 degree right angles.
(M) Where any street deflects at an angle of ten degrees or more, a connecting curve shall be required having a minimum centerline radius of 300 feet for arterial and collector streets and 125 feet for local streets.
(N) Streets shall have centerline offsets of at least 125 feet.
(O) A tangent at least 100 feet long shall be provided between reverse curves.
(P) At street intersections, where curb and gutter and/or sidewalks will be constructed, property lines shall be rounded by a circular arc, said arc having a minimum tangent length of 20 feet.
(Q) Street intersections with more than four legs and Y-type intersections where legs meet at acute angles shall not be permitted.
(R) Maximum grades for all streets shall be 8%.
(S) Required gradations for subbase and base aggregate shall be as follows.
Sieve Size | Subbase | Base |
Sieve Size | Subbase | Base |
6" | 100% | |
3" | 60 – 100% | |
1" | 40 – 80% | 100% |
3/4" | 85 – 100% | |
No. 4 | 40 – 70% | |
No. 8 | 30 – 55% | |
No. 40 | 5 – 60% | |
No. 200 | 0 – 15% | 4 – 12% |
(T) Intersections of local roads with major arterials or highways shall be kept at a minimum of 600 feet between centerlines.
(U) Road intersection grades shall be in compliance with Figure 2. Stopping and sight distances will be maintained at all intersections and on all curves within the development.
(V) All changes in grade shall be connected by vertical curves of sufficient radius to provide a smooth transition and proper sight and stopping distance. Refer to American Association of State Highway and Transportation Officials’ (AASHTO) Policy on Geometric Design of Highways and Streets, 1984.
(W) Driveway approaches onto roads shall not exceed 12% grade as calculated from the nearest shoulder elevation. Approaches shall be a minimum of 20 feet wide between the road right-of-way and the shoulder line of the road. A driveway approach shall not extend beyond the shoulder line of the road. All building lots shall be capable of accommodating at least one approach complying with the requirements of this division (W).
(X) Culverts shall be sized to provide hydraulic capacity necessary for storm water runoff. The volume of storm water runoff shall be figured on the basis of a 25-year, 24-hour storm. Minimum culvert sizes shall be 18 inches underneath any county road and 12 inches under any driveway approach. Culverts may be either corrugated metal pipe, reinforced concrete pipe, or other acceptable material. For roads that are between 6% and 8% grade, a culvert shall be installed an average of every 400 feet beneath the road to eliminate water build-up in the ditch.
(Y) Placement of all utilities underneath the roadway shall be completed prior to the placement of any subbase gravel.
(Z) County road right-of-way shall be identified with property pins and steel fence posts at the time of acceptance by the county.
(AA) The standards set out herein shall be considered minimum standards. Additional standards may be required where special conditions warrant.
(BB) Where these design standards may be in conflict with other local ordinance provisions, these standards shall prevail.
(Ord. 95-3, passed 9-25-1995; Ord. 1995-3, passed 9-25-1995)