(A) Road classification. The developer or subdivider shall use the table below to determine the design requirements and road classification type for existing or proposed streets. The Planning Director or designee shall determine the classification of streets where there is a discrepancy or the classification cannot be determined from the table. In addition, the standards established by this table may be amended by the Commission if it determines that it is necessary for reasons of safety, efficiency, maintenance, anticipated problems or future growth.
(1) Arterial system. Arterials are categorized by their linkages to cities or larger towns and they generally provide interstate or intercounty service. They are capable of attracting travel over long distances.
(2) Collector system. The collector system generally serves intracity travel as opposed to state and county wide movements. The trips associated with a collector are predominantly shorter than those associated with arterial routes. Consequently, lesser design speeds are used and the design standards are generally less than that of arterial routes. Collector routes provide service and connections to the arterial system. They are categorized as serving the more important intracity routes.
(3) Local roadways. The local roadway system primarily provides access to adjacent land and to the wider network. It serves principally shorter trips and constitutes all roadways not classified as arterials or collector roads. To further designate this category and the design parameters required a set of subcategories are defined based on the roadway traffic volumes. In some cases, as that of a subdivision for example, right-of-way is limited and numerous driveway cuts are needed. In these instances, a curb and gutter section may be required.
Street Classification and Requirements
Type of Street - Category | Average Daily Traffic (ADT) | Min. Pavement Width | Min. Shoulder Width* | Rights- of-Way Width** | Max. Street Grade | Design Speed (mph) |
Type of Street - Category | Average Daily Traffic (ADT) | Min. Pavement Width | Min. Shoulder Width* | Rights- of-Way Width** | Max. Street Grade | Design Speed (mph) |
Local - I | ADT < 400 | 20 feet | 4 feet | 50-60 feet | 12% | 30 |
Local - II | 400 < ADT <3,000 | 22 feet | 4 feet | 50-60 feet | 11% | 40 |
Local - III | ADT > 3,000 | 24 feet | 4 feet | 50-60 feet | 10% | 45 |
Collecto r - I | ADT < 1,000 | 24 feet | 4 feet | 60-70 feet | 10% | 40 |
Collecto r - II | 1,000 < ADT < 3,000 | 24 feet | 8 feet | 60-70 feet | 9% | 45 |
Collecto r - III | ADT > 3,000 | 24 feet | 10 feet | 60-70 feet | 8% | 45 |
Arterial - I | ADT < 5,000 | 24 feet | 10 feet | 80 feet | 6% | 45 |
Arterial - II | ADT > 5,000 | 24 feet | 12 feet | 80 feet | 5.5% | 45 |
Notes: * Minimum shoulder widths will vary depending on the need and size of pavement section(s). ** Right-of-way widths will vary depending on the need and size of sidewalks, on-street parking areas, turning lanes, and the presence of utility lines. The standards established by this table can be amended by the Plan Commission if determined necessary for safety, efficiency, maintenance, anticipated problems or future growth as advised by the Planning Department and County Engineer. | ||||||
(B) Public right-of-way width. The minimum width of right-of-way for a public street shall be as listed in the table above. Additional right-of-way width shall be required whenever, due to topography or turn lanes, additional width is necessary to provide adequate earth slopes, accommodate additional pavement width and afford maintenance. Easements may be provided in lieu of additional right-of-way dedication for maintenance or construction in locations where additional right-of-way dedication would be problematic to lot development.
(C) Additional right-of-way. Subdivisions that adjoin existing public street rights-of-way shall dedicate additional right-of-way according to the table above if the minimum right-of-way does not exist along the property road frontage. The entire right-of-way shall be provided where any part of the subdivision is on both sides of the existing street; and one half of the right-of-way shall be provided, as measured from the centerline, for subdivisions that are located only on one side of the existing street.
(D) Pavement width. No public street shall be constructed except in conformance with the minimum pavement widths as listed above in the table above. (See § 151.01 for Type of Street.)
(E) Street grades. Grades of both public and private streets in proposed subdivisions or developments shall not be greater than as listed in the table above. The maximum grade may be waived however, upon request of the applicant to the County Engineer, if, due to topographic conditions, access is prohibited or requires excessive grading. The County Engineer shall determine whether a waiver will be granted. To determine the waiver the County Engineer shall review the slope percent proposed, length of slope, lot access, vertical curve at landing and drainage to determine if the waiver request can be permitted safely. The County Engineer shall forward a letter indicating whether to approve the waiver and any conditions that are necessary for safety to the Planning Commission.
(F) Horizontal curves. Central angles of horizontal curves shall be kept to a minimum unless there is sufficient radius length to minimize the severity of the curve. At no time shall the radius of the centerline of a proposed street be less than 300 feet for collector streets, and 150 feet for local streets, except at intersections or divided roadways. The tangent distance between horizontal curves of proposed street centerlines shall not be less than 100 feet for all streets.
(G) Vertical curves. Any change in grade of proposed streets shall be transitioned by a vertical curve. The minimum length for a vertical curve shall be 15 times the absolute value of the algebraic difference of the grades (in percent) of the two tangents for collector streets. The minimum length for a vertical curve shall be ten times the absolute value of the algebraic difference of the grades (in percent) of the two tangents for sub-collector, local, cul-de-sac, and court streets.
(H) Intersections. The two centerlines of proposed streets at their intersection shall be as nearly to a right angle as possible and that angle at no time shall be less than 75 degrees. For residential subdivisions, the radius of the curve at the intersection of the two right-of-way lines shall not be less than 25 feet, and for the intersection of the two pavement edges, the radius curve shall not be less than 25 feet.
(1) For industrial and commercial subdivisions, the radius of the curve at the intersection of the two right-of-way lines shall not be less than 40 feet, and for the intersection of two pavement edges, the radius curve shall not be less than 45 feet. The Commission may, in certain situations, increase the minimum radii based upon existing road conditions and traffic patterns.
(2) There shall be no greater than four basic street legs at any proposed intersection unless the intersection is divided. Merging lanes, deceleration lanes, Y intersections, etc., are considered as being parts of one street leg or approach.
(3) Proposed new intersections along one side of an existing street shall, wherever practicable, coincide with any existing intersection on the opposite side of such street. Street jogs with centerline offsets of less than 150 feet shall not be permitted. Where a local street is proposed to intersect with an arterial street, the alignment of the streets shall be mandatory. Proposed street intersections with arterials shall be at least 800 feet apart and at least 800 feet from any existing street intersection(s) along the arterial. Proposed intersections with existing streets shall not be closer than 175 feet to an intersection of two existing streets as measured from edge of pavement.
(4) Intersections shall be designed with a flat grade wherever practical. In hilly or rolling areas, at the approach to an intersection a leveling area shall be provided having not greater than a 2% grade at a distance of 60 feet for collector or arterial streets and 3% for local streets as measured from the nearest right-of-way line of the intersecting street.
(5) Where any street intersection will involve earth banks or existing vegetation inside any lot corner that would create a traffic hazard by limiting visibility, the developer shall cut such ground and/or vegetation (including trimming trees) in connection with the grading of the public right-of-way to the extent deemed necessary by the County Engineer to provide an adequate sight distance.
(I) Dead-end streets. A DEAD-END STREET is a street, or a portion of a street, or a system of streets that is connected to other public streets from only one point of access. The regulations set forth in this division shall apply to dead-end streets, portions of streets, or street systems.
(1) Dead-end streets or street systems shall not serve more than 30 dwelling units for residential subdivisions unless an acceptable alternative access is approved by the Plan Commission. An acceptable access alternative may include, but is not necessarily limited to: connectivity to an existing or planned open street or street system, wider streets, navigable sidewalks or medians, stub streets or an emergency access, as set forth later in this section.
(2) A dead-end street or street system shall not be more than 1,200 feet in length. The length of a dead-end street or street system shall be the cumulative distance measured from the intersection of the centerlines of the dead-end street and the intersecting public street to the center of the radial turnaround(s) provided at the terminus of the street or street system. This 1,200-foot length requirement may be waived by the Plan Commission.
(3) All turnarounds for dead-end streets must be approved through the Technical Review Committee and shall generally conform to the standards set forth in Appendix C. The radius of all turnarounds shall consist of 50 feet of right-of-way and 40 feet of pavement for residential uses and 60 feet of right-of-way and 50 feet of pavement for commercial and industrial uses.
('74 Code, § 14-14) (Ord. passed 11-25-67; Am. Ord. 2019-009, passed 5-13-19) Penalty, see § 10.99