The following minimum standards apply to all public streets and design criteria shall apply unless deemed unwarranted by written recommendation of the city engineer and transportation division director. Said standards and criteria shall be supplemented by other applicable existing engineering and construction requirements and standards as specified by the city engineering and transportation divisions.
A. General:
1. Where higher standards have not been established as specified in Subsection A.1 of this section, all streets shall be platted, designed, and constructed according to the principles outlined in the transportation division's Street and Intersection Typologies Design Guide and the design and constructions for public streets adopted by the city. Exceptions to the Street and Intersection Typologies Design Guide may be granted through a planned development subject to Chapter 21A.55 or by the transportation director based on the following standards:
a. The subdivision serves 10 lots or fewer and justifies a narrower cross section than what is identified in the Street and Intersection Typologies Design Guide;
b. A different street design is warranted due to the slope, waterways, existing infrastructure, or other similar unique circumstance that doesn't generally exist on other properties within the same zoning district;
c. The adopted general plan establishes a different guide or standard for streets in the geographic area where the proposed subdivision is located; and
d. The subdivider provides an alternative cross section for a street that provides all of the required components identified in the guide but in a different arrangement that is consistent with the intent of the specific street type.
B. Street Grades: Curves and sight distances shall be subject to approval by the city engineering division, to ensure proper drainage and safety for vehicles and pedestrians. The following principles and standards shall be observed:
1. Grades of streets shall be not less than 0.5% and not greater than 7%;
2. The maximum grade applies at the street centerline; and
3. Short runs of steeper grades may be permitted if there are no objections from the fire department, transportation division, and city engineer.
C. Vertical Alignment of Nonintersecting Streets: Transition curves over crests of hills shall be designed to provide both a smooth transition from upward movement to minimize potential roller coaster effect and to provide safe stopping sight distance at all times. The stopping sight distance is the distance required to safely stop a vehicle after viewing an object calculated on a formula set forth in standards adopted by the transportation division.
D. Vertical Alignment at Street Intersections: Transition curves shall be required to provide a smooth transition from road grade to intersections. For an approach distance ("A") from each edge of the intersecting street line, the grade may not exceed 2%. The minimum length of the approaches ("A") and transition curves ("L") shall be calculated upon the formulas below:
A = The minimum approach distance required where grade may not exceed 2% from the curb line of the intersecting street. Said distance of "A" shall be not less than 35' for intersections with local streets and not less than 100' for intersections with major or arterial streets.
L = The minimum transition curve length required between points of tangency, "X", where L = 10(a), "a" being the difference between the grade of the road less the grade of "A".
E. Intersection Site Distance: Intersections shall be planned and located to provide as much sight distance as possible. In achieving a safe road design, as a minimum, there shall be sufficient corner sight distance for the driver on the approach roadway to cross the intersecting street without requiring approaching traffic to reduce speed. Such corner sight distance is a field of vision which shall be measured from a point on the approach roadway at least 15' from the edge of the intersecting roadway pavement at a height of 3.5' on the approach roadway. The minimum corner sight distance for local streets (30 miles per hour design speed) shall be 350'. For collector streets (40 miles per hour design speed) the minimum corner sight distance shall be 450'.
F. Horizontal Alignment of Streets: In addition to the specific street design standards set forth above, horizontal alignment shall be subject to the following criteria:
1. Consistent with topography, alignments shall be as straight as possible;
2. Maximum curvatures shall be avoided whenever possible;
3. Consistent patterns of alignment shall be sought. Sharp curves at the end of long tangents or at the end of long flat curves shall be avoided;
4. Short lengths of curves shall be avoided even for very small deflection angles;
5. Flat curvatures shall be provided on long fills;
6. Compound circular curves with large differences in radii shall be avoided;
7. Direct reverse curves shall be avoided; a tangent shall be used between them;
8. "Broken back curves" (two curves in the same direction on either side of a short tangent or large radius curve) shall be avoided; and
9. To effectuate the above general criteria, the minimum curve centerline radii for local streets and collector streets shall be 100' and 150', respectively. The maximum allowable degree of curvature shall be 23° for local streets and 12.5° for collector streets.
G. Street Lighting: Lighting shall comply with the policies and standards outlined in the Salt Lake City Street Lighting Master Plan.
H. Curb, Gutter, and Sidewalks: The following principles and standards shall apply to the design and installation of curbs, gutters, sidewalks, and pedestrianways. Low impact development standards may be substituted at the discretion of the engineering and transportation divisions, according to best practices as determined by the public utilities department:
1. Vertical curbs and gutters as shown on the city's standard detail drawings shall be required in all subdivisions unless otherwise approved by the city engineer and transportation director. The minimum gutter slope at a street intersection and at the crest and sag of vertical curves is 0.5%;
2. Sidewalks shall be designed to comply with ADA Guidelines. Sidewalks are required on both sides of a street except when the transportation director authorizes an exception when a subdivision includes land that is in a manufacturing zone located west of I-215, BP Business Park District located west of I-215, or EI Extractive Industries District.
3. Sidewalks shall normally be located within the street right of way and shall be required to be a minimum width as indicated in this subsection:
a. Four feet wide in any FR, R-1, R-2, or SR zoning districts when adjacent to a park strip;
b. Five feet wide in any FR, R-1, R-2, or SR zoning districts zoning districts when the sidewalk is directly adjacent to the back of curb;
c. Six feet wide in all other zoning districts unless specified otherwise in those districts;
d. Eight feet wide in the central business district; or
e. Ten feet wide along Main Street in the central business district.
The transportation director may require the subdivider to provide a pedestrian impact study to determine if additional width for a sidewalk is necessary based on the proportional impact the subdivision may have on the sidewalks within the subdivision;
I. Protection Strips: Protection Strips: Where subdivision streets create frontage for contiguous property owned by others, the subdivider may, upon approval by the city engineer create a protection strip not less than one foot in width between said street and adjacent property, to be deeded into joint ownership between the city and subdivider. Such a lot requires an agreement from the subdivider contracting to deed to the owners of the contiguous property the one foot or larger protection strip lot for a consideration named in the agreement, such consideration to be not more than the cost of street improvements properly charged to the contiguous property as determined by the city engineering division in their estimate of cost of improvements for the subdivision. Jointly owned protection strip lots shall not be permitted at the end of or within the boundaries of a public street, or proposed street, or within an area, or abutting an area, intended for future public use.
J. Traffic Report: New subdivisions have traffic impacts on existing street systems that may or may not be adverse in nature. The transportation director may require the subdivider to provide a detailed traffic report of the effects and impacts of the proposed development. This report shall detail the expected number of trips to be generated, the type of vehicles expected, and the times of day that the most severe impact can be expected. It shall also detail the effect on street capacity by the development, as well as nearby intersections that will be impacted by the development's traffic as may be designated by the transportation division director. Based on a review of the traffic impact study, the transportation division may require additional mitigations including street improvements and other multi-modal transportation enhancements. (Ord. 73-23, 2023)