A. Connectivity Of Streets, Sidewalks, And Trails: Subdivisions shall provide for continuation and extension of arterial, collector and local streets, sidewalks and trails in accordance with the following standards:
1. Arterial streets must be located and extended in general accordance with the metropolitan planning organization of Johnson County arterial street plan and Iowa City comprehensive plan.
2. All streets, sidewalks, and trails should connect to other streets, sidewalks, and trails within the development, and to the property line to provide for their extension to adjacent properties. Each subdivision must contribute to the larger interconnected street pattern of the city to ensure street connectivity between neighborhoods, multiple travel routes resulting in the diffusion and distribution of traffic, efficient routes for public and emergency services, and to provide direct and continuous vehicular and pedestrian travel routes to neighborhood destinations.
3. The road system shall be designed to permit the safe, efficient, and orderly movement of vehicular and pedestrian traffic; to meet the needs of the present and future population served; to have a simple and logical pattern and allow that pattern to continue through adjacent properties; and to respect natural features and topography.
4. Use of cul-de-sacs and other roadways with a single point of access should be avoided. Cul-de-sacs will be considered where it can be clearly demonstrated that environmental constraints, existing development, access limitations along arterial streets, or other unusual features prevent the extension of the street to the property line or to interconnect with other streets within or abutting the subdivision.
5. Where the area is subject to Article 14-2H (Zones And Standards), thoroughfares are to create walkable neighborhoods with redundant routes for vehicular, bicycle and pedestrian circulation. The arrangement of thoroughfares shall provide for the alignment and continuation of existing or proposed thoroughfares into adjoining lands where the adjoining lands are undeveloped and intended for future development, or where the adjoining lands are undeveloped and include opportunities for such connections.
a. Thoroughfare rights-of-way shall be extended to or along adjoining property boundaries to provide a roadway connection or thoroughfare stub for development, in compliance with 15-3-4 (Layout Of Blocks And Lots), for each direction (north, south, east, and west) in which development abuts vacant land.
b. All stubs for thoroughfares are to connect with future thoroughfares on adjoining property and be designed to transition appropriately.
B. Minimum Access Standards: Adequate street access to an area or neighborhood is required as part of subdivision approval or prior to the approval of additional subdivision lots. The standards in this subsection are intended as minimum standards in areas where connectivity is limited by topography, previous development patterns, or other unusual features and shall not be used as a means of circumventing the street connectivity standards set forth in subsection A of this section. The following guidelines will be used by the city in determining whether additional street access is a prerequisite to additional lots or developable parcels being approved by the city.
1. Additional access may be required if a proposed development will result in any portion of a street that provides a single means of access to an area being overburdened with traffic. "Overburdened" shall be defined as a projected volume which exceeds the midpoint design volume as follows:
a. Local street: Five hundred (500) vehicles per day.
b. Collector street: Two thousand five hundred (2,500) vehicles per day.
2. Projected traffic volumes shall be determined by using the most recent average daily traffic count when available, and adding it to projected traffic generation as determined by the city. In the absence of a recent traffic count, projected traffic volumes shall be calculated by using projected traffic generation for both existing and proposed development.
3. Additional means of access may also be required if any of the following conditions exist or will exist if additional lots or developable parcels are approved:
a. There are physical features that may increase the probability of blockages along the single means of access to the development. These physical features include, but are not limited to: slopes eight percent (8%) or greater; floodplains as designated by the federal emergency management agency; a bridged or culverted roadway; trees adjacent to the roadway with trunk diameter greater than four inches (4"); a grade separated highway; or a railroad.
b. The existing access is insufficient to provide efficient, safe, and/or cost effective routes for the provision of public and emergency services for the proposed development.
c. The street, which provides a single means of access to the area, is a local or collector street along which there are existing or proposed facilities that may increase the probability of pedestrian-motor vehicle conflicts. These facilities include, but are not limited to, schools, daycare centers and parks.
d. There are land uses located along the subject street that serve special populations, which may increase the volume of emergency vehicle trips. These uses include, but are not limited to, adult daycares, facilities serving elderly persons, or persons with disabilities.
4. For a situation requiring additional means of access based on the above criteria, a single means of access may be permitted as a temporary condition. A temporary condition is one in which there is secured, written assurance from the private subdivider that the road, which will provide the necessary access, will be constructed within three (3) years of development or, alternatively, said access is scheduled for construction no later than the third year of the then current capital improvements program of the city.
C. Street Types:
1. Table 15-1, "Standards For Street Rights Of Way", of this section provides a summary of various street types. The information in this table is intended to provide guidance for the design of the street network within a subdivision, except for those subdivisions regulated by Article 14-2H (Form- Based Zones And Standards). When designing a subdivision, street types should be chosen based on the intended function of the street and anticipated level of traffic. The city will review the proposed streets and determine the appropriate street type based on the factors set forth in this section.
2. Where a subdivision is regulated by Article 14-2H (Form-Based Zones And Standards), streets shall meet the following thoroughfare standards.
a. Thoroughfares shall conform with allowed thoroughfare types and shall comply with 14-2H-9 (Thoroughfare Type Standards).
b. Thoroughfares that pass from one Form-Based Zone to another may transition in their streetscape along the thoroughfare's edges. For example, a thoroughfare in a more urban zone (e.g.,T4 Main Street) with commercial uses may have wide sidewalks with trees that transitions to narrower sidewalks with a planting strip in a less urban zone (e.g., T4 Neighborhood Medium) with residential uses.
c. Thoroughfares shall substantially comply with the Form-Based Code Future Land Use Map in the Comprehensive Plan. Variations from the Future Land Use Map may be approved for thoroughfares where sensitive areas are present, or where the following standards are met:
(1) Thoroughfare types may be substituted with other thoroughfare types allowed by the zone, except for the following streets: South Gilbert Street, Sand Road SE, McCollister Boulevard, Sycamore Street, Sycamore Street SE, and Lehman Avenue.
(2) The alignment of thoroughfares may change where connections to existing street stubs are retained, the new alignment complies with 15-3-4 (Layout Of Blocks And Lots), and single-loaded streets continue to abut civic or open space.
(3) A Passage (14-2H-9L) may replace another thoroughfare type shown on the Form-Based Code Future Land Use Map where all affected design sites retain direct street or alley access. A passage may be removed or replaced by another thoroughfare type where all abutting design site(s) retain direct street access.
(4) An alley (14-2H-9K) may be added in compliance with 15-3-4 (Layout Of Blocks And Lots). An alley may be removed from locations identified on the Form-Based Code Future Land Use Map where the alley is not in a T4MS zone and all design sites abutting the alley have direct street access to a street other than the following: McCollister Boulevard and South Gilbert Street.
D. Dedication Of Right Of Way: Land shall be dedicated to the city for all public street rights of way within the development and for any public street right of way that is needed for streets that abut or will abut the development.
Minimum Right Of Way Width | Pavement Width | Number Travel Lanes | Parking | Maximum Grade | Sidewalk Width |
Minimum Right Of Way Width | Pavement Width | Number Travel Lanes | Parking | Maximum Grade | Sidewalk Width | |
Residential alley/rear lane | 20 feet | 16 feet | 2 | No | 12 percent | n/a |
Commercial alley/rear lane | 20 feet minimum/varies | 20 feet/varies | 2 | No | 10 percent | n/a |
Loop street1 | 100 feet minimum/varies | 22 feet | 1 shared | Yes, on 1 side | 10 percent | 4 feet residential side of street only |
Low volume cul-de-sac2 | 50 feet | 22 feet | 1 shared | Yes, on 1 side | 10 percent | 4 feet both sides |
Cul-de-sac | 60 feet | 26 or 28 feet | 2 | Yes3 | 10 percent | 5 feet both sides |
Local residential street | 60 feet | 26 or 28 feet | 2 | Yes3 | 12 percent | 5 feet both sides |
Local commercial/industrial street | 60 feet | 28 feet | 2 | Yes | 8 percent | 5 feet both sides |
Collector street (all land uses) | 66 feet | 31 feet | 2 | Yes | 10 percent for residential; 8 percent for commercial or industrial | 5 feet both sides |
Collector street with bike lanes | 66 feet | 34 feet | 2 | No | 8 percent | 5 feet both sides |
2 lane arterial street | 100 feet minimum | 31 feet | 2 | No | 8 percent | 8 feet one side/5 feet one side |
Arterial street with bike lanes | 100 feet minimum | 34 feet | 2 | No | 8 percent | 8 feet one side/5 feet one side |
4 lane arterial street | 100 feet minimum | 54 feet/varies depending if median is included | 4 | No | 8 percent | 8 feet one side/5 feet one side |
Arterial street with parking | 100 feet minimum; more may be required depending on parking configuration | Varies, based on number of lanes and whether parking is parallel or angled | 2 | Yes | 8 percent | 8 feet one side/5 feet one side |
3 lane arterial street | 100 feet minimum | 46 feet/varies depending if median is included | 3 | No | 8 percent | 8 feet one side/5 feet one side |
Notes:
1. Loop streets provide access for 12 or fewer dwellings.
2. Low volume cul-de-sacs provide access to 10 or fewer single-family dwellings.
3. For residential streets with less than 28 feet of pavement width, parking is restricted to one side.
E. Measurements And Construction Standards:
1. All right of way improvements must be designed and constructed according to the design and construction standards established by the city. Said standards are on file in the office of the city engineer.
2. All street widths shall be measured back of curb to back of curb.
3. The minimum outside radius of the pavement of cul-de-sac bulbs and loop streets is thirty nine feet (39'). A center median is required at the center of the cul-de-sac bulb with a minimum radius of eleven feet (11'). For loop streets a median is also required with a minimum width of thirty feet (30'). In residential areas, center medians for cul-de-sacs and loop streets are required to be landscaped to at least the S1 standard as described in title 14, chapter 5, article F, "Screening And Buffering Standards", of this code. The subdivider's agreement shall designate and set forth procedures for property owners or a homeowners' association to maintain the landscaped area within the center median of loop streets and cul-de-sacs. Said instrument shall provide that if said services are not provided as required therein, the city shall have the right to perform said services, and the cost thereof shall be a lien and charge against all of the subject lots.
F. Street Intersections:
1. A maximum of four (4) legs are allowed at any one intersection.
2. The distance between street intersections must be at least one hundred twenty five feet (125') centerline to centerline.
3. Intersections of street centerlines shall be between eighty degrees (80°) and one hundred degrees (100°).
4. Corner lots abutting on an arterial or collector street shall have a minimum radius of fifteen feet (15') at the intersection.
5. Dead end streets and alleys are not permitted except at subdivision boundaries abutting undeveloped areas. In such cases a temporary fire apparatus accommodating turnaround may be required and, if required, must be constructed to city specifications.
G. Traffic Calming Features:
1. The street network, block length, and layout of lots should be designed in a manner that discourages speeding traffic and unsafe driving behavior.
2. In order to minimize the potential for speeding traffic and create a safer environment for pedestrians and bicycles, the city may also, in cases where it is warranted, require traffic calming features to be designed into the subdivision. These features may include, but are not limited to, discontinuous streets, curb extensions, raised crosswalks, medians, or traffic circles.
H. Street Names: The city reserves the right to deny the use of street names that are not in the public interest. Street names must be consistent with the following standards, unless an exception is approved by the city:
1. In order to ensure safe and efficient provision of public and emergency services, each proposed street name shall be distinct from other street names within the larger metropolitan area;
2. Street names that are overly lengthy, difficult to pronounce, or that may be considered inappropriate or unappealing shall be avoided;
3. For new streets, the following rules apply:
a. The term "street", should be used for a nondead end roadway aligned in a north-south direction;
b. The term "avenue" should be used for a nondead end roadway aligned in an east-west direction;
c. The term "boulevard", "road", or "drive" may be used for a roadway that is aligned neither in a north-south nor east-west direction, but which changes direction or meanders;
d. The terms "lane", "court", "circle", "place" should be used for cul-de-sacs or low volume loop streets.
4. Cul-de-sacs or low volume loop streets may use the same name as the roadway with which it intersects. For example, a cul-de-sac that intersects with Rose Avenue may be named "Rose Court". However, if more than one cul-de-sac or loop street intersects with Rose Avenue, an additional "Rose" name may not be used.
5. Similar names may not be used for streets that are in different locations within the city. For example, the name "Rose Drive" may not be used in one neighborhood if there is already a "Rose Avenue" in a different neighborhood.
I. Private Streets:
1. Private streets in single-family residential areas are not allowed.
2. Requests for private streets in multi-family, commercial, and industrial areas will be considered, provided that connectivity to adjacent properties is not needed and the responsibilities for maintenance, snow removal, garbage service, and street sweeping is clearly established according to the provisions of subsection I3 of this section.
3. If private streets are approved, the subdivider must submit a legally binding instrument setting forth the procedures to be followed for maintaining private streets and providing garbage service, snow removal, street sweeping, and for financing these services. Such costs shall be shared by all owners of property located within the subdivision, or designated portion thereof, through the use of an owners' association or other entity satisfactory to the city. Said instrument shall provide that if said services are not provided as required therein, the city shall have the right to perform said services, and the cost thereof shall be a lien and charge against all of the owners of lots so designated in the subdivision.
J. Cost Sharing For Pavement Overwidth: In the event arterial or collector streets are required in a subdivision, the city shall pay for the excess pavement required over that required for a twenty eight foot (28') wide local street. The city engineer shall calculate the excess cost. Such cost sharing shall be according to the procedure set forth by the city manager. Any payment for pavement overwidth by the city shall be pursuant to state law.
K. Cost Sharing For Street Upgrades:
1. At the discretion of the city, subdivisions may be approved that access existing public streets that do not meet city standards, provided the subdivider contributes toward the future reconstruction cost of bringing the segment of the subject street that abuts the subject property to city standards. When determining whether such an approval will be granted, the city will evaluate the street based on factors such as roadway surface, sight distance, anticipated traffic levels, and pedestrian/bicycle facilities. If the city permits a development to access a street that does not meet city standards, the subdivider shall contribute to the cost as follows:
a. Local Streets: Local streets are streets that serve as access to property and carry insignificant amounts of through traffic. Therefore, the subdivider shall pay one hundred percent (100%) of the cost of upgrading a local street to city standards for that segment of the street that abuts the subject property. If the subdivider controls land on only one side of a local street, they will be required to contribute fifty percent (50%) of the cost of upgrading the subject street segment to city standards. The city will expect the subdivider of property on the other side of the street to contribute the other fifty percent (50%) of the costs at such time as that land is subdivided/developed. Costs to reconstruct the street will be determined by the city engineer.
b. Collector Streets: Collector streets are streets that collect traffic from a subdivision or neighborhood, and direct it to and from the arterial street. The function of a collector street is fifty percent (50%) access to property, and fifty percent (50%) through traffic. Therefore, the subdivider will be required to contribute fifty percent (50%) of the cost to upgrade a collector street to city standards for that segment of the street that abuts the subject property, with the city contributing the other fifty percent (50%). If a subdivider controls land on only one side of the collector street, they will be required to contribute twenty five percent (25%) of the total cost for the subject street segment. The city will expect the subdivider on the other side of the collector street to contribute the other twenty five percent (25%) of the cost at such time as that land is subdivided/developed. Costs to reconstruct the street to city standards will be determined by the city engineer.
c. Arterial Streets: Arterial streets have the primary function of carrying traffic through and between neighborhoods. The function of an arterial street is twenty five percent (25%) access to property, and seventy five percent (75%) through traffic. Therefore, the subdivider will be required to contribute twenty five percent (25%) of the cost to upgrade an arterial street to city standards for that segment of the street that abuts the subject property, with the city contributing the other seventy five percent (75%). If a subdivider controls land on only one side of the arterial street, they will be required to contribute 12.5 percent of the total cost of the subject street segment. The city will expect the subdivider on the other side of the arterial street to contribute the other 12.5 percent of the cost at such time as that land is subdivided/developed. Costs to reconstruct the street to city standards will be determined by the city engineer. (Ord. 08-4313, 8-26-2008; amd. Ord. 21-4866, 11-16-2021)