Article 9 Parking, Mobility, and Access

The provisions of this article are intended to balance the City's goals of:

Promoting walking, bicycling, and transit use.

Providing reasonable amounts of off-street parking for shoppers, visitors, and residents.

Reducing on-street parking demands on nearby residential streets.

The parking requirements of this article are designed to respond to the general day-to-day needs of businesses, shoppers, employees, residents, and visitors while also avoiding the negative impacts that can result from requiring excessive quantities of off-street parking.

The provisions of this article are also intended to help protect the public health, safety and general welfare by:

Promoting economically productive use of land; and

Providing flexible methods of responding to the transportation and access demands of various land uses in different areas of the City.

Applicability.

General. Off-street parking and loading must be provided and maintained in accordance with the provisions of this article. Unless otherwise expressly stated, the regulations apply to all zones and uses.

New uses and development. The parking regulations of this article apply to all new buildings constructed and all new uses established in all zones.

Change of use. If a newly established use on a lot requires more off-street parking than the use that most recently existed on that lot, additional off-street parking is required in an amount equal to the difference between the parking required for the new use and the parking that would have been required for the previous use if the parking requirements of this article had been applicable to the previous use. There is no requirement to address parking deficits associated with existing, lawfully established uses.

Enlargements and expansions.

The parking regulations of this article apply whenever an existing building or use is enlarged or expanded to include additional dwelling units, floor area, or other units of measurement used in establishing off-street parking requirements.

In the case of enlargements or expansions that trigger requirements for additional parking, additional spaces are required only to serve the enlarged or expanded area, not the entire building or use. There is no requirement to address parking deficits associated with existing, lawfully established buildings or uses.

(5)

Damage or destruction.

When a building or use that has been damaged or destroyed is re-established, off-street parking or loading facilities must also be re-established or continued in operation in an amount equal to the number maintained at the time of such damage or destruction. It is not necessary, however, to restore or maintain parking facilities in excess of those required by this chapter.

If a building or use that has been damaged or destroyed is not re-established in accordance with § 660-127F, the use's nonconforming parking rights are lost and such use may be re-established only in compliance with the off-street parking regulations of this article.

(6)

Nonconforming parking. Existing uses that were lawfully established before this chapter's effective date specified in § 660-1C and that do not comply with the minimum parking requirements of this article are deemed to have nonconforming parking rights. Additional parking spaces are required to be provided for uses with nonconforming parking rights only if such use triggers a requirement to provide additional parking pursuant to Subsection B(2) through (5) of this section.

(7)

Maintenance. Required off-street parking spaces must be maintained for the life of the principal use.

Use of off-street parking areas.

Required off-street parking spaces are intended to serve the off-street parking needs of residents, tenants, patrons, employees, and guests of the principal use.

Required off-street parking spaces may not be used for the storage, display or sale of goods equipment or materials, except that the Zoning Officer is authorized to approve temporary use of off-street parking areas for display and sales of holiday and seasonal items (e.g., Spring gardening supplies and Christmas trees).

No junk vehicle storage or motor vehicle repair work of any kind is permitted in a required parking space. This provision is not intended to prohibit residents of the subject property from servicing vehicles they own. The Zoning Officer is authorized to require proof of vehicle ownership.

Required parking spaces may be used for electric vehicle charging.

§ 660-84 Motor vehicle parking ratios.

Off-street motor vehicle parking spaces must be provided in accordance with the minimum and maximum ratios established in Table 660-10 unless otherwise expressly stated. See § 660-86 for provisions governing off-street parking exemptions, reductions, and credits.

Table 660-10. Parking Ratios
	Minimum Number of Motor Vehicle Parking Spaces Required
Use	MX-D and GX-D Zones	All Other Zones	Notes
Residential
Household Living, 1 unit	No minimum	N1 and N2 Zones: 1 per dwelling unit All other zones: 2 per dwelling unit
Household Living, 2 - 4 units	No minimum	N1 and N2 Zones: 1 per dwelling unit All other zones: 1.5 per dwelling unit
Household Living, 5+ units	0.75 per dwelling unit	1 per dwelling unit
Student Residence	N/A	2 per dwelling unit
Group Home	See § 660-36C(4)(g)	See § 660-36C(4)(g)
Congregate Living	1 per 4 beds	1 per 4 beds	Plus 1 per 2 employees
Commercial
Adult Use	No minimum; maximum number may not exceed 125% of the minimum requirement that applies in all other zones	1 per 100 sf
Animal Service		Outdoor general: 1 per 15 animals All other: 1 per 400 sf
Child Care Center		1 per 12 enrollees
Child Care, Group		1 per nonresident employee
Consumer Service, Indoor		1 per 400 sf
Day Care Center, Adult		1 per 12 enrollees
Eating and Drinking Places		1 per 5 seats	1 per 400 sf if no fixed seating or when located in multi-tenant center
Entertainment, Spectator/Participant		1 per 5 seats	1 per 400 sf if no fixed seating
Funeral and Mortuary Service		1 per 50 sf
Lodging		1 per 2 guest rooms	Plus spaces required for other on-site uses
Office		1 per 400 sf
Retail Sales		1 per 400 sf
Self-Service Storage, Indoor		Established per § 660-85H
Vehicle Sales and Service		1 per 400 sf sales area	Plus 2 per service bay and 1 per 2 employees
Manufacturing and Industry
50,000 square feet or less	No minimum	1 per 4 employees
More than 50,000 square feet	No minimum	1 per 2 employees
Civic and Institutional
Cemetery	No minimum	No minimum
College or University		1 per 3 off-campus, full-time students	Plus 1 per 2 employees; plus spaces required for dormitory or other residential use
Community Assembly		1 per 4 seats	1 per 400 sf if no fixed seating
Detention or Correctional Facility		1 per 2 employees
Hospital		1 per 4 beds	Plus 1 per 2 employees
Library or Cultural Exhibit		1 per 400 sf
Parks and Open Space	No minimum	Established per § 660-85H
Governmental Use		1 per 2 employees
School		1 per 6 students in 11th — 12th grades	Plus 1 per 2 employees
Infrastructure and Utilities, Minor		No minimum
Infrastructure and Utilities, Major		1 per 2 employees	1 space minimum

sf = square feet of floor area (see § 660-85C)

§ 660-85 Calculations.

Multiple uses. Lots containing more than one use or tenant must provide parking in an amount equal to the total aggregate number of spaces required for each use or tenant on the lot except when a shared parking arrangement is approved in accordance with § 660-87.

Rounding. When calculating off-street parking requirements, any fractional result of less than one-half is rounded down to the next lower whole number and any fractional result of one-half or more is rounded up to the next higher whole number.

Floor area (square feet). For purposes of calculating off-street parking requirements based on floor area (sf), the sum of the gross horizontal areas of the several floors of the building or portion of building devoted to such use, measured to the centers of all partitions, are counted. However, the following are not counted:

Areas devoted primarily to dead storage, building maintenance, or utilities;

Restrooms and dressing rooms;

Window showcases;

§ 660-86 Parking exemptions, reductions, and credits.

Employee meal areas and conference rooms;

(5)

Area devoted to off-street parking or loading facilities, including aisles, ramps, and maneuvering space; and

(6)

Basement floor area other than area devoted to retailing activities, to the production or processing of goods, or to business or professional offices.

Bench seating. In stadiums, sport arena, religious institutions, and other places of assembly in which patrons or spectators occupy benches, pews, or other similar seating facilities, each 30 inches of such seating are counted as one seat.

Employees or students. For the purpose of computing parking requirements based on employees or students, calculations must be based on the average number of persons working on the largest shift or the average enrollment, whichever is applicable.

Outdoor seating. Unenclosed outdoor seating areas containing 20 or fewer seats are not counted when calculating off-street parking requirements for restaurants. All unenclosed outdoor seating areas with capacity for more than 20 seats are counted.

Unlisted uses. Upon receiving a permit or development application, the Zoning Officer is authorized to apply the off-street parking ratio specified for the listed use that is deemed most similar to the proposed use or establish an off-street parking requirement for the proposed use in accordance with § 660-85H.

Establishment of parking ratios. The Zoning Hearing Board is authorized to establish required minimum parking ratios for unlisted uses and in those instances where authority to establish a requirement is expressly granted. Such ratios must be established on the basis of (1) a similar use determination, as described in § 660-35D; (2) parking data provided by the applicant; or (3) other information available to the Zoning Hearing Board. Parking data and studies must include estimates of parking demand based on reliable data collected from comparable local uses or on external data from credible research organizations, such as the Urban Land Institute (ULI) and the Institute of Transportation Engineers (ITE). Comparability will be determined by density, scale, bulk, area, type of activity and location. Parking studies must document the source of all data used to develop recommended requirements.

Reductions and credits. The methodology for calculating allowed parking reductions and credits is established in § 660-86C.

Applicability. The off-street parking exemptions, reductions, and credits allowed in this section may not be used to reduce off-street parking requirements for accessory dwelling units, as established in § 660-44B.

Parking exemptions.

Small nonresidential uses.

Off-street parking is not required for nonresidential uses on lots with an area of 2,000 square feet or less.

Off-street parking is not required for nonresidential uses occupying floor area of 2,000 square feet or less if the lot occupied by such use is in an MX-C Zone abutting North 7th Street.

Lane rowhouses. Off-street parking is not required for lane rowhouses.

Urban and town rowhouses. Off-street parking is not required for principal dwelling units in urban rowhouse and town rowhouse buildings when all of the following criteria are met:

Applicable zoning regulations prohibit front or street yard parking on the subject lot;

Driveway access restrictions or other constraints prohibit access to off-street parking spaces in allowed locations; and

The constraints or other circumstances affecting the provision of otherwise required off-street parking spaces are not the result of the actions of the property owner (i.e., not self-created).

Parking reductions and credits.

General.

The parking reductions and parking credits allowed by this section may be applied singularly or in combination, provided that the total reduction in required parking does not exceed 50% of the minimum requirements stated in Table 660-10.

When applying parking reductions and parking credits, parking reductions must be applied before parking credits.

When applying multiple parking reductions and credits, such reductions and credits must be applied in descending order of reduction, with the greatest percentage reduction applied first (e.g., 25%, 15%, etc.). If reductions or credits are of equal value, the reductions are applied sequentially (e.g., 25%, 25%). In all cases, the first reduction or reduction is applied to the minimum parking requirement stated in Table 660-10, with each additional reduction or credit applied to the newly calculated amount of required parking. Mathematical rounding allowed by § 660-85B is applied to the final parking amount calculated after factoring in authorized parking reductions and credits.

For example, Table 660-10 requires that a 100-unit apartment building in an MX-D Zone provide a minimum of 75 parking spaces (0.75 spots per dwelling unit). If such building was eligible to take parking reductions for providing affordable housing (25% reduction) and for its location in a high-capacity transit-served location (25% reduction), required parking would be calculated as follows:

First, calculate the initial 25% reduction: [75 spaces minus (75 x 0.25)] = 56.25 spaces;

Second, calculate and apply the second 25% reduction [56.25 minus (56.25 x 0.25)] = 42.19 spaces, which is rounded to 42 spaces or a reduction of 44%.

[3]

Third, apply any available parking credits until the not-to-exceed reduction threshold of 50% is met, in this example, up to four additional parking spaces may be removed before reaching the maximum 50% parking reduction.

Parking reductions.

Affordable housing. Off-street parking requirements are reduced by 25% for all dwelling units in a building occupied by affordable housing units meeting the eligibility criteria of § 660-36A(3)(d).

High-capacity transit-served locations (high-capacity transit). Off-street parking requirements are reduced by 25% for uses located on lots within 800 feet of a high-capacity transit bus stop.

Parking credits.

Public parking. Nonresidential uses are credited for parking spaces within a nearby public parking lot or public parking garage, as follows:

Minimum parking requirements for the subject use are reduced by one parking space for every four parking spaces within the public parking lot or garage;

The nearest pedestrian entrance to the public parking lot or garage must be located within 800 feet of the lot on which the subject use is located; and

[3]

The parking facility must be open to the general public from at least 6:00 a.m. to 10:00 p.m.

Car-share and bike-share service. Car-share and bike-share parking credits apply to nonresidential uses that are required to provide 15 or more motor vehicle parking spaces and to residential projects that are required to provide 25 or more motor vehicle parking spaces, as follows:

The number of required motor vehicle parking spaces is reduced by four spaces for each parking space that is leased by a City-approved car-share program for use by a car-share vehicle.

The number of required motor vehicle parking spaces is reduced by two spaces for uses that provide space for a City-approved bike-share program facility with a minimum of eight bicycle parking docks.

Electric vehicle charging. In parking lots containing more than 15 parking spaces, each parking space equipped with Level 2 or Level 3 (DC) electric vehicle charging equipment is credited as two motor vehicle parking spaces for purposes of satisfying the minimum off-street parking ratios of Table 660-10. To receive credit, each electric vehicle charging station-equipped parking space must be publicly accessible and be identified by signs.

Motorcycle and scooter parking. In parking lots containing more than 15 parking spaces, the provision of motorcycle or scooter parking spaces may be credited toward satisfying the minimum off-street parking ratios of Table 660-10 at the rate of one motor vehicle parking space for each two motorcycle or scooter parking spaces. To receive credit, each motorcycle and scooter space must have a concrete surface and minimum dimensions of four feet by eight feet. Areas restricted to motorcycle and scooter parking must be identified by signs.

§ 660-87 Shared parking.

General. Shared parking refers to the practice of two or more users who need parking at different times making use of the same motor vehicle parking spaces. Shared parking is encouraged as a means of conserving scarce land resources, reducing stormwater runoff, reducing the heat island effect caused by large paved areas, and improving community appearance.

Eligibility. The Zoning Hearing Board is authorized to approve shared parking arrangements for nonresidential uses that have different periods of parking demand in accordance with the special exception procedures of § 660-115. Required residential parking spaces and accessible parking spaces (for people with disabilities) may not be shared.

Submittal requirements and methodology. Applicants proposing to use shared parking as a means of reducing overall motor vehicle parking requirements must submit the following with the special exception application:

The names and addresses of the uses and of the owners or tenants that are sharing the parking;

The location and number of parking spaces that are being shared;

A shared parking study conducted in accordance with accepted methodology approved by the City, prepared by an independent traffic engineering professional under the supervision of the City and paid for by the applicant, demonstrating that the hours, size, and mode of operation of the respective uses does not create a substantial conflict in the peak parking demands of the uses for which shared parking facilities is proposed, and there is adequate parking to meet the parking needs for each use; and

A properly drawn legal instrument, which must be filed as a deed restriction on all impacted properties, guaranteeing access to the parking for the shared parking users. The agreement is subject to approval by the City and must be recorded with the county recorder of deeds.

§ 660-88 Alternative compliance.

The minimum motor vehicle and bicycle parking requirements of this article are not intended to be a barrier to development or redevelopment or to make development and redevelopment economically impractical or negatively impact the viability of businesses. In order to allow for flexibility in addressing the actual expected parking demand of specific uses, modifications of the minimum and maximum off-street parking requirements of this article may be approved through the special exception procedures of § 660-115 only if:

The applicant submits a parking study demonstrating that the parking ratios of Table 660-10 or Table 660-11 do not accurately reflect the actual day-to-day parking demand that can reasonably be anticipated for the proposed use based on field surveys of observed parking demand for similar use within the City or on external data from credible research organizations, such as the Urban Land Institute (ULI) or the Institute of Transportation Engineers (ITE);

The Zoning Hearing Board determines that the other exemption, reduction, and credit provisions of this article are infeasible or do not apply; and

The Zoning Hearing Board determines that the proposed alternative parking ratios are consistent with the general purposes of § 660-83A and are not likely to cause material adverse impacts on traffic circulation and safety or on the general welfare of property owners and residents in the surrounding area.

§ 660-89 Bicycle parking.

Purposes.

Short-term bicycle parking. Short-term bicycle parking is generally intended to serve the needs of cyclists who park their bicycles for fewer than three-hour time periods, including customers, clients, messengers, and other short-term visitors.

Long-term bicycle parking. Long-term bicycle parking is generally intended to serve the needs of cyclists who park their bicycles for more than three-hour periods, including employees, residents, students, and commuters.

Spaces required. Short-term and long-term bicycle parking spaces must be provided in accordance with the minimum bicycle parking ratios of Table 660-11.

Table 660-11. Bicycle Parking
Use/Building Type	Bicycle Parking Spaces (Min)
Residential Uses
0 — 4 Dwelling Units	None
5+ Dwelling Units	1 per 5 dwelling units^[1]
Commercial Uses
All Commercial Uses	1 per 5,000 sf^[2]
Manufacturing and Industry
All Manufacturing and Industry Uses (based on employees)	0 — 5: None 6 — 20: 2 spaces^[2] Over 20: 1 per 10 employees^[2]
Civic and Institutional
College or School	1 per classroom
Community Assembly	1 per 5,000 sf^[2]
Library or Cultural Exhibit	1 per 5,000 sf

Table Notes:
sf = Square feet of floor area (see also § 660-85C).
[1]	At least 50% must be long-term bicycle parking spaces.
[2]	At least 25% must be long-term bicycle parking spaces.

Location and design.

General. All required bicycle parking spaces must:

Consist of bike racks or lockers that are anchored so that they cannot be easily removed;

Be of solid construction, resistant to rust, corrosion, hammers, and saws;

Allow both the bicycle frame and at least one wheel to be locked with the bicycle in an upright position using a standard U-lock;

Be designed and installed so as not to cause damage to the frame, wheels, or components;

(e)

Be accessible without interference from or moving adjacent bicycles and not result in a parked bicycle obstructing a required walkway; and

(f)

Have minimum dimensions of two feet in width by six feet in length, with a minimum overhead vertical clearance of seven feet.

Short-term bicycle parking spaces. Short-term bicycle parking spaces must be at least as conveniently located as the most convenient non-disabled motor vehicle parking provided for the subject use. If no motor vehicle parking is provided, short-term bicycle parking spaces must be located within 50 feet of a building entrance. Short-term bicycle parking must be located on the subject lot, unless the City approves a proposal to allow private bicycle parking facilities to be located in the right-of-way. Public bicycle parking spaces may be credited toward meeting short-term bicycle parking requirements if such bicycle parking spaces comply with the location requirements of this paragraph.

Long-term bicycle parking and storage spaces. Long-term bicycle parking spaces must:

Be located with direct access by the bicycle rider, with no more than 50% of the required spaces requiring the use of stairs or elevators;

May not be located in dwelling units or on dwelling unit balconies;

Must protect the entire bicycle, its components and accessories against theft and inclement weather, including wind-driven rain and snow;

Must be designed to allow bicycles to be securely locked to a bicycle rack in:

A bike storage room that is accessible only to authorized users and has at least two electrical outlets;

§ 660-90 Location of off-street parking.

A bicycle locker with a separate access door for each bike; or

[3]

An attended bike storage room.

General. Except as otherwise expressly stated in this article, required off-street parking areas must be located on the same lot as the building or use they are required to serve or on an abutting lot under the same ownership. For purposes of this provision, lots separated only by a C street or alley are considered abutting lots.

Off-site parking.

When allowed. All or a portion of required off-street parking for residential uses in MX-D and GX-D Zones and for nonresidential uses in all zones may be provided off-site, in accordance with the regulations of this section. Required accessible parking spaces and required parking for residential uses outside of MX-D and GX-D Zones may not be located off-site.

Location. Allowed off-site parking areas must be located within 800 feet of the use served by such parking, measured between the nearest pubic entrance door of the use to be served and the outer perimeter of the furthest parking space within the off-site parking lot. Off-site parking lots are allowed only in zones that permit off-street parking as a principal use or that allow the use to be served by the off-site parking (see Table 660-4).

Design. Off-site parking areas must comply with all applicable parking area design regulations of § 660-91.

Control of off-site parking area. The property to be occupied by the off-site parking facilities must be under the same ownership as the lot containing the use to be served by the parking. The off-site parking area may be under separate ownership only if a legal instrument is provided guaranteeing the long-term availability of the off-site parking. The long-term lease or agreement is subject to approval by the City and must be recorded with the county recorder's office. Any proposed changes to the agreement must also be submitted to the City for review and approval.

Truck parking in N Zones. Tractor-trailer trucks, trailers of a tractor-trailer combination, truck with a Class 5 license or above, or trucks with an aggregate gross vehicle weight of more than 11,000 pounds may not be parked for more than two hours per day on a lot in an N Zone, except for:

Routine parking allowed as part of a lawful nonconforming nonresidential use; and

§ 660-91 Parking areas layout and design.

Temporary parking for on-site construction or repair activities.

Applicability. The parking layout and design regulations of this section apply to all off-street parking lots for motor vehicles, whether containing required or non-required parking spaces.

Ingress and egress. All parking areas and driveways must be designed to allow vehicles to enter and exit a street and cross public sidewalks in a forward motion, except that this requirement does not apply to lots occupied by house building types when motor vehicle access is to a "local street," as that term is defined in Chapter 350, Land Development and Subdivision.

Driveways.

All driveways must be a minimum of 10 feet in width except as otherwise expressly stated in this chapter.

Residential driveways may not exceed 20 feet in width, except as required to accommodate necessary turning radii, as determined by the City Engineer. All other driveways are limited to a maximum width of 22 feet, except as required to accommodate necessary turning radii, as determined by the City Engineer.

Ribbon driveways may be used to provide individual access to single-household detached houses provided that:

The ribbons are located only on the driveway;

The driveway apron is paved across its entire width;

The ribbons are at least two feet in width and no more than three feet in width; and

The ribbons are at least three feet apart measured from their nearest edges.

Driveways must be designed to provide a stopping space not exceeding a 6% grade 20 feet behind the right-of-way line.

Parking stall size.

Standard spaces. Except as expressly allowed for compact spaces or as expressly required for accessible parking spaces, parking spaces must be at least 8.5 feet in width and at least 18 feet in length. Up to two feet of the front of a standard parking space, as measured from a line parallel to the direction of the bumper of a vehicle using the space, may be pervious landscape area instead of paved. Such areas count toward any applicable interior parking lot landscape requirements.

Compact spaces. Up to 20% of required parking spaces may be designated, designed, and marked as compact parking spaces in multi-level parking structures, employee parking lots containing more than 50 spaces and parking areas served by an on-site attendant. Such compact spaces must be at least eight feet in width and at least 16 feet in length.

Aisle widths.

Drive-aisle within off-street parking areas must be designed in accordance with Table 660-12, which shows minimum required aisle widths for various parking layouts (angles).

Table 660-12. Aisle Widths
Stall Angle	Minimum Aisle Width (Feet)
0° (parallel) to 25°	12.0 (20 feet for two-way traffic)
25°-47°	13.0 (one-way)
48°-52°	14.0 (one-way)
53°-58°	15.0 (one-way)
59°-62°	16.0 (one-way)
53°-68°	17.0 (one-way)
69°-72°	18.0 (one-way)
73° or more	20.0 (one-way) 24.0 (two-way)

Note: Minimum aisle widths for parking stall angles of 45 degrees or greater may be reduced by two feet if minimum parking stall width is at least 9.5 feet.

Vertical clearance. All required parking spaces must have overhead vertical clearance of at least seven feet.

Surfacing. All off-street parking areas and access drives must have dustless, durable, all-weather surface. Pervious pavement or a pervious pavement system designed to manage stormwater, only as part of a plan designed by a registered professional and approved by the City Engineer, are allowable. Examples of pervious pavement or a pervious pavement system include pervious asphalt, pervious concrete, modular pavers designed to funnel water between blocks, lattice or honeycomb shaped concrete grids with turf grass or gravel filled voids to funnel water, plastic geocells with turf grass or gravel, reinforced turf grass or gravel with overlaid or embedded meshes, resin bound pervious pavement systems, and similar structured and durable systems approved by the City Engineer. Gravel, turf, or other materials that are not part of a structured system designed to manage stormwater are not allowed as surfacing material.

Maximum surface area. All off-street parking areas and access drives must be designed using the smallest surface areas required for vehicular use. Areas outside of required drive aisles, parking spaces, sidewalks, and loading areas must be landscaped per § 660-74.

Marking. In off-street parking areas for more than four vehicles, the location of each parking space must be identified by surface markings at least four inches in width and be maintained so as to be readily visible at all times.

Drainage. Adequate provision must be made for the management of stormwater from parking areas in conformance with applicable stormwater management regulations.

Setbacks. All off-street parking areas must be designed and constructed so that parked vehicles are set back in accordance with the building type regulations of Article 4. Off-street parking areas on sites with no permanent principal building must be set back at least one foot from lot lines.

Sight triangles. Off-street parking is prohibited within the intersection and driveway visibility triangles established in § 660-70.

Lighting.

Parking areas and related passageways and driveways must be illuminated during hours of operation for:

All nonresidential uses; and

Residential uses served by 20 or more parking spaces.

Outdoor lighting used to illuminate off-street parking areas is subject to the light and glare performance standards of § 660-82J.

Tandem and stacked parking.

Tandem parking spaces that involve the placement of one parking space behind another may be used to satisfy parking requirements for residential uses when the parking spaces are assigned to the same dwelling unit.