5203.1       Design Criteria: This section governs the general design requirements for the following street classifications (see notes on following page):

Notes:

(1)   At end of cul-de-sac, minimum design speed = 10 mph; with corresponding minimum horizontal radius = 25 ft.; minimum stopping sight distance = 75 ft.; minimum K Crest = 3; and minimum K Sag = 5 (2 with lighting).

(2)   All street design is subject to local governing agency approval.

(3)   K values for crest and sag vertical curves may be determined using the chart on figure 1 or 2, or in accordance with AASHTO - A Policy on Geometric Design of Highways and Streets. Figure III-41 and III-43. The upper range K value shown on page 52-3 [the above table] shall be used unless otherwise approved by the local governing agency.

(4)   See figure 4 for typical residential street layout.

(5)   Consideration should be given to providing a 15 ft. minimum wide utility easement along each side of the right-of-way for residential access streets and 10 ft. wide utility easements for all other streets.

(6)   Absolute maximum grade = 10% for residential collectors, 13% for residential local streets, and 15% for residential access streets.

(7)   Absolute minimum grade = 0.8% and should only be used for relatively short distances.

(8)   The 10.5 ft. lane width for residential access streets shall only be used in a planned development where a minimum of four off-street parking spaces are provided for each dwelling unit.

(9)   30 mph design speed with corresponding horizontal and vertical curve design criteria may be used for industrial commercial collector streets under special conditions when approved by the City Engineer.

(10) The minimum radii shown is based on the AASHTO design for low-speed urban streets with no super elevation except for major arterials. The minimum radii for major arterials is based on 2% super elevation.

5203.2       Maximum and Minimum Gradient: The maximum and minimum gradient for streets as noted in Section 5203.1 may be exceeded only upon written approval of the City.

5203.3       Shoulder Gradients: The finished grade within the limits of the right-of-way shall slope from 2% one-quarter (¼) inch vertical to one foot horizontal minimum, to 4% one-half (½) inch vertical to one foot horizontal maximum measured above the back of the curb. The grading gradients may be varied only upon written approval of the City. Back slopes beyond the R/W line shall be 3:1 maximum, 4:1 desirable.

5203.4       Tangent Length: No tangent length shall be required between reverse curves for residential access and local streets. The minimum tangent length between reverse curves shall be 100 feet for collector/industrial streets. Major and minor arterial streets shall comply with current AASHTO guidelines.

5203.5       Off-Center Street Intersections: Off-center street intersections shall be separated as shown on Figure 3(M).

5203.6       Intersection Angle: It is desirable for all intersections to meet at approximately a 90 degree angle. Skewed intersections should be avoided and in no case should the angle be less than 75 degrees.

5203.7       Intersecting Minor/Major Arterial Streets: Where any minor or major arterial streets intersect each other, the crowns of both streets shall be uniformly transitioned into a plane at the intersection unless otherwise approved. Changes from one cross slope to another should be gradual.

5203.8       Curb Radii: When 2 streets of different classification intersect, the higher classification street shall govern the curb radii dimension listed in 5203.1. Equivalent three-center compound curves may be used in lieu of a single radius curve. Curb ends facing the flow of traffic shall have a 5-foot taper from full height to zero.

5203.9       Sight Distance at Intersecting Streets: Sight distance triangles at intersecting side streets shall be in accordance with the current edition of A Policy on Geometric Design of Highways and Streets, AASHTO. Every effort shall be made to select intersection locations so that the maximum sight distance is possible.

5203.10     Considerations for Connection to Existing and Future Streets: Consideration shall be given to the horizontal and vertical alignment of roadways where they connect to existing streets or where roadways may be extended in the future. Where a new street is to connect to an existing street, all deteriorated or cracked asphalt within 5 feet of the connection point shall be removed to a point where sound material is found. Existing pavement is to be saw cut for the entire width of the street to a minimum depth of 6 inches. If full-depth pavement removal is required, the subgrade shall be re- compacted to 95% of standard density.

5203.11     Pavement Section: Pavement shall be constructed upon compacted subgrade and of materials and the minimum thickness as shown on the standard drawings for the applicable street classification.

5203.12     Pavement Transition: Reduction in pavement width in the direction of traffic flow shall be accomplished by a taper. The minimum desirable length for merging taper shall be determined by the formula L = WS2/60 where posted speeds are 45 mph or less. The formula L = W x S should be used for roadways having a posted speed limit greater than 45 mph. Under either formula, L = taper length in feet, W = width of the closed lane in feet, and S = design speed in mph.

5203.13     Culs-de-Sac: At locations where streets are to be terminated and a vehicular connection between adjacent streets is not required, the termination shall be a cul-de-sac. Such cul-de-sac shall be constructed with a minimum radius of 39 feet to the back of the curb if there are no islands located in the cul-de-sac.

5203.14     Temporary Turn-Arounds: At locations where streets will be temporarily terminated and which will be extended at a later date, and said street extends beyond the intersection of an adjacent street more than 150 feet, a temporary cul-de-sac shall be constructed with a minimum radius of 35 feet. The temporary cul-de-sac shall be constructed of asphaltic concrete with a minimum depth of 8 inches. Curb and gutter will not be required. The cul-de-sac shall be constructed within the limits of temporary easement.

Temporary turn-arounds shall be located so that they do not interfere with permanent development. They should normally be located on property adjacent to the property to be served. For new subdivision plats, they should be located on property beyond the limits of the plat.

5203.15     Driveway Grades: Driveway grades shall conform to the typical section of the street within the right-of-way. Any deviations shall be approved by the local government official with the following limitations: Driveways shall attain a minimum elevation of 6 inches above the gutter elevation within the right-of-way with a maximum grade of 8%. The algebraic difference in grades at the right-of-way on crest drives shall be 8% maximum and on sag drives shall be 12% maximum. The maximum driveway grade outside the right-of-way shall be 15%.

5203.16     Access for the Disabled: Ramps shall be required at all planned sidewalk-curb intersections in accordance with standard practice and approved by the City. Non-standard driveways and alleys will also be designed to accommodate the handicapped.

5203.17     Street Lighting: All street lighting shall be designed in accordance with Section 5800 of the APWA design criteria unless otherwise directed or approved by the City.

5203.18     Storm Drainage: All storm drainage shall be designed in accordance with Section 5600 of the APWA design criteria unless otherwise directed or approved by the City.

5203.19     Underdrains: In areas that have known subsurface moisture problems, underdrains or drainage blankets shall be designed.

5203.20     Erosion Control within R/W Limits: As a minimum, all grass areas in the R/W shall be seeded and mulched to control erosion on to the roadway. All construction projects that have exposed grading require temporary erosion control measures. Temporary erosion control must be approved by the City Engineer.

5203.21     Survey Monument Boxes: Monument boxes conforming to Figure 5 shall be installed at all quarter section corners involved in the street construction. The monument boxes shall be set by a Registered Land Surveyor licensed in the state the monumentation work is performed.

5203.22     Traffic Impact Studies: Required where developments have adverse impact on existing traffic conditions.

5203.23     Obstructions: Rigid structures such as poles and hydrants shall be placed a minimum horizontal distance of 1.5 feet from the face of curb to edge of obstruction. When required, guardrail and barricades shall be installed in accordance with the AASHTO Roadside Design Guide or local policies. Vertical clearance of a minimum 14.5 feet shall be provided. Along sidewalks, a minimum vertical clearance of 7 feet shall be provided.

5203.24     Other Design Criteria: Design criteria not covered by this document shall be in accordance with the most current edition of A Policy on Geometric Design of Highways and Streets by the American Association of State Highway and Transportation Officials (AASHTO) or other applicable AASHTO design guides.