Planning Terms Glossary

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Accessory Use: A use that is customarily incidental and subordinate to the principal use of a lot or the main building, and located on the same lot as the principal use or building.

Adequate Public Facilities Ordinance (APFO): A County ordinance requiring a determination that public facilities are adequate to accommodate growth resulting from approval of a subdivision application.

Affordable housing: Housing units built or operated under federal, state, or County government programs, including government ownership and subsidized financing; or by the private sector under a government requirement, such as the Moderately Priced Dwelling Unit (MPDU) law. Affordable housing programs are designed to serve people with varying incomes up to 70 percent of the Area Median Income (AMI), although Workforce Housing allows incomes of up to 120 percent of the AMI.

Afforestation: The establishment or forest or tree cover in accordance with Chapter 22A of the Montgomery County Code on an area from which it has always or very long been absent, or the planting of open areas which are not in forest cover. (Chapter 22A-3 Definitions)

Agricultural Reserve: Areas of Montgomery County planned and zoned primarily for agricultural uses, which include the majority of the County’s remaining working farms and certain other non-farm land uses.

Amenity: Privately provided facilities within a development that enhance public enjoyment. Amenities can include physical enhancements to public and private spaces that make those spaces more inviting to the general public.

Annual Growth Policy: A policy document adopted annually by the County Council intended to match the timing of private development with the availability of public services. It includes criteria and guidance for the administration of the Adequate Public Facilities Ordinance (APFO) and establishes development capacity staging ceilings for each policy area of the County. The overall purpose is. The AGP is prepared by the Planning Board based on data collected through administration of the Adequate Public Facilities Ordinance and through population and housing projections. It is coordinated with the Executive’s Capital Improvements Program and is transmitted to the County Executive in Final Draft Form. The County Executive submits recommendations in writing to the County Council. The Council, after public hearings, must adopt the AGP by June 30 of each fiscal year. Learn more

Arterial Mobility: Observed travel time data is compared with calculated travel times based on the speed limit (the fastest allowable speed) yielding a ratio of congested speed to free flowing speed called Arterial Mobility. Arterial Mobility is translated into Level of Service (LOS) grades (A-F, A being the best) that can be used to describe road conditions and capacity for planning purposes.

Arterial Travel Times and Speeds: Measurement of travel time between fixed start and end points that provides an understanding of congestion levels along roadway segments. When combined with intersection congestion data in the form of Critical Lane Volumes (or CLVs), arterial travel times and speeds provide an understanding of travel conditions. In this instance, the term ‘Arterial ‘refers to any of the County’s most heavily traveled north-south or east-west routes and corridors in the County, such as Georgia Avenue (MD 97).

Average Daily Traffic (ADT): A commonly used measure of traffic flow that reflects the total volume of vehicular traffic passing a given point during a typical 24-hour period.


Base density: The maximum number of dwelling units or square footage of nonresidential space per unit of gross land area (usually expressed in acres) that is allowed by zoning, exclusive of any additional density that may be permitted based on the use of the optional method of development, the application of transferable development rights (TDRs), floating zones, cluster provisions, planned development zones, or the MPDU ordinance.

Berm: A continuous linear earthen mound of varying height designed and placed to screen the view of and reduce the noise from adjacent, incompatible uses, such as highways.

Bikeway Classifications:

  • Bicycle boulevard: Shared roadways that prioritize the movement of bicycles over motor vehicles. These roadways are designed to be comfortable and attractive to cyclists with a wide range of abilities and ages. They include treatments such as traffic calming and diversion, signage and pavement markings, and intersection crossing improvements to reduce traffic speeds and volumes and discourage non-local motor vehicle traffic.
  • Bicycle lane: A portion of a roadway which has been designated by striping, signing and pavement markings for preferential or exclusive use by bicyclists.
  • Bikeway: Any path or way that is designated as being open to bicycle travel, regardless of whether such facilities are exclusive or shared.
  • Shared Use Path: A recreational trail (bikeway) physically separated from motorized vehicular traffic by an open space or barrier and either within the roadway right-of-way or within an independent right-of-way. Shared Use Paths may be used by pedestrians, skaters, wheelchair users, joggers, and other non-motorized users.
  • Signed Shared Roadway: A roadway which is designed for both bicycle and motor vehicle travel and designated as a preferred route for bicycle use. This may be an existing local street, a street with wide curb lanes, or road with paved shoulders.

Board of Appeals – A five-member board appointed by the County Council to hold hearings and rule on special exceptions and variances. The Board’s powers and responsibilities are defined in the County Zoning Ordinance.

Boulevard: See Street Character, Functional Classifications, and Road Code Designations

Brownfield: Land containing an abandoned, idled or underused industrial or commercial facility where expansion or redevelopment may be affected by environmental contamination.

Buffer: An area of land designed or managed for the purpose of separating or providing a transition between two or more land areas whose uses may conflict or be seen as incompatible.

Buildout: The end point of development for a site or area, reached when all development capacity conveyed by zoning, subdivision, or site plan has been used.

Building Lot Termination Easement: A form of an agricultural easement that runs with the land in perpetuity and extinguishes the right to construct a residential dwelling unit on land located in the Agricultural Reserve and zoned Rural Density Transfer.

Building elevation: A scale drawing of the front, rear, or side of a building or structure showing dimensions and architectural details.

Building line: A line, parallel to a lot line, creating an area into which a structure must not project. A building line may be established that is more restrictive than the minimum setback required for structures in a particular zone.

Building Lot Termination (BLT): A transferable development right (TDR) created from land that: is at least 25 acres; is capable of being served by an individual sewage treatment unit which meets the requirements of Chapter 27A (Montgomery County Code), and applicable regulations issued under that Chapter; and is located in the Rural Density Transfer (RDT) Zone, and could be transferred by a BLT easement under this Chapter (Chapter 59 – Montgomery County Zoning Ordinance). When a BLT easement is recorded in the land records, the easement extinguishes the right to build a dwelling unit in the RDT zone; this attribute distinguishes a BLT from other TDRs.

Building permit: A permit issued by the Montgomery County Department of Permitting Services after several levels of project review that allows construction to proceed.

Bus Rapid Transit (BRT): A fixed-guideway transit system on which buses operate on rights-of-way that are separated, either physically or through signing and marking, from general purpose lanes used by automobiles. BRT system elements also typically include off-board fare collection systems and advanced transit information systems.

Example of BRT – Ontario Transitway, Ontario, Canada


Capital Improvements Program (CIP): A six-year comprehensive statement of the objectives of capital programs with cost estimates and proposed construction schedules for specific projects. The proposed Montgomery County CIP is submitted by the County Executive to the County Council every two years and a general amendment is typically submitted in the off-years. Capital Improvements Programs (CIP).

The CIP is the tool through which locally funded public facilities, such as sewers, local roads, schools, libraries, and parks can be scheduled and built, in coordination with and guided by, the Annual Growth Policy and area master plans. It is used in conjunction with the Adequate Public Facilities Ordinance to program public facilities needed to service subdivisions.

Central Business District (CBD): Any one of the County’s principal business districts that has been so designated in section 59-C-6.12 of the Montgomery County Zoning Ordinance. The County’s CBDs are Friendship Heights, Bethesda, Silver Spring, and Wheaton.

Certified Site Plan: A final document that incorporates all elements of the site plan approved by the Planning Board, including a project data table, all necessary engineering drawings, specific references to all agency approvals required by the Planning Board approval resolution, and a complete copy of the approval resolution.

Change or Mistake Rule: A requirement that, before approving a zoning change to a Euclidean zone through a local map amendment, the County Council must determine if there has been a change in the character of the neighborhood significant enough to warrant a rezoning or if a mistake was made in the original zoning process.

Charrette: A brief, intense design workshop in which community teams work with staff, local elected officials, the landowner, the developer, and all interested citizens to produce a plan that addresses community needs.

Controlled Major Highway: See Street Character, Functional Classifications, and Road Code Designations

Corridor Cities Transitway (CCT): A master-planned transit line traveling north from the Shady Grove Metro Station to serve the communities of Rockville, Gaithersburg, Germantown, and Clarksburg. The Transitway will use bus rapid transit (BRT) or light rail transit (LRT). The first 14 miles are under study by the Maryland Transit Administration.

Cluster development: An optional development technique under zoning and subdivision regulations that allows residential dwellings to be placed on smaller than usual lots that have been grouped or clustered in order to leave some land undivided and available as common area or open space.

Conditional use: A use that is permitted if certain operational or site conditions are met.

Conservation easement: A restriction placed on the land and the natural features of the land usually shown on the record plat of subdivision or recorded by a metes and bounds description. Its terms and conditions are recorded in the County’s land records. Most commonly, the agreement prohibits removing vegetation, and prohibits changing the scenic and arboreal character of the land without written permission from the Planning Department.

Consolidated Transportation Program: A six-year comprehensive statement of the objectives of capital programs with cost estimates and proposed construction schedules for specific projects. The proposed Maryland State CTP is prepared by the Governor and adopted by the State legislature. The CTP is the tool through which State funded public facilities can be scheduled and built, in coordination with and guided by, the County’s Growth Policy and area master plans. It is used in conjunction with the Adequate Public Facilities Ordinance to program public facilities needed to service subdivisions.

Corridor: An uninterrupted area of developed or undeveloped land paralleling a transportation route (such as a street, highway, or rail) or the land within one-quarter mile of both sides of designated high-volume transportation facilities, such as arterial roads. If the designated transportation facility is a limited access highway, the corridor extends one-quarter mile from the interchanges.

Country Arterial: See Street Character, Functional Classifications, and Road Code Designations

Country Road: See Street Character, Functional Classifications, and Road Code Designations

Critical Lane Volume (CLV): The sum of traffic volumes that cross at a single point in an intersection. The resulting product is used to determine the level of service of an intersection in a Local Area Transportation Review (LATR).


Dedication: Donation of land to a public agency for parkland, school sites, road and transit rights-of-way, etc., in connection with the development of a subdivision or lot.

Demand Management Program: Actions designed to alleviate traffic congestion by reducing dependence on the single-occupancy vehicle through transit, carpooling, and other alternatives.

Density: The amount of development allowed on a property based on the ratio of residential units to property size, or the ratio of commercial building square footage or mixed-use floor area to lot area, expressed as Floor Area Ratio (FAR).

Density Bonus: An incentive tool offering developers the ability to exceed the maximum allowable residential housing density if they agree to construct more affordable housing units than required by law. In Montgomery County, the Zoning Ordinance allows for a density bonus of up to 22 percent above a zone’s base density in exchange for providing additional moderately priced dwelling units (MPDUs) above the 12½ percent required.

Development District: A district in which government may levy special assessments or taxes on real property to help pay for infrastructure improvements in that district.

Development Plan: A plan required to be submitted as a part of an application for the rezoning of a piece of land.

Development Pipeline: The amount of approved residential and non-residential development that has not yet been built.

Downzoning: A rezoning action that lowers the density allowed on a property.

Dwelling unit: A building or a portion thereof that provides complete living facilities including, at a minimum, facilities for cooking, sanitation, and sleeping, for not more than one family.


Easement: A contractual agreement to gain temporary or permanent use of, and/or access through, a property. Permanent easements should be shown on a subdivision record plat.

Eminent Domain: The right of federal, State, and local governments to condemn and force the sale of private property for public purposes.

End-State Development: Future land use as envisioned by the most recent master plan, assuming total buildout of the plan’s land use and zoning recommendations. In practice, development densities rarely exceed 80 percent of planned ultimate land use.

Environmental Buffer: The outermost limits of a wetland, wetland buffer, 100-year floodplain, and a perennial or intermittent stream and stream buffer. An environmental buffer may also include hydraulically connected steep slopes and erodible soils.

Environmental Impact Statement (EIS): A document, prepared by a federal agency that evaluates the environmental impact of government proposals for large projects, such as highways or facilities that could significantly affect the quality of the human environment. Environmental Impact Statements are used as decision-making tools and are required by the National Environmental Policy Act.

Euclidean zone: See Zoning


Floating zone: See Zoning

Floodplain: The area along a stream or drainage course, lake, or pond, which, after total development of the watershed, would experience inundation by stormwater runoff equivalent to that which would occur on the average of once every 100 years.

Floor Area Ratio (FAR): The ratio of the gross floor area of a building to the area of the lot on which it is located. Parking and non-leasable space of the building are generally excluded from the computation. For example, a building with a gross floor area of 43,560 square feet on a one-acre lot would have a 1.0 FAR.

Forest: A biological community dominated by trees and other woody plants (including plant communities, understory, and forest floor) covering a land area which is 10,000 square feet or greater, and at least 50 feet wide. For the purposes of implementing the Montgomery County Forest Conservation Law, this definition is interpreted to mean those areas that have at least 100 trees per acre with at least 50 percent of those trees having a two-inch or greater diameter at 4.5 feet above the ground. Forest does not include orchards.

Forest Conservation Plan: A document that outlines the specific strategies for retaining, protecting, and reforesting or afforesting areas on a site, pursuant to the 1991 Maryland Forest Conservation Act. Forest Conservation Plans are approved by the Planning Board with conditions that are binding on applicable private and public development, and certain land disturbing activity.

Forest Stand Delineation: The collection and presentation of data on existing vegetation in relation to the natural resources on a site proposed for development or land disturbing activity.

Freeway: See Street Character, Functional Classifications, and Road Code Designations

Functional Master Plan: A master plan addressing either a system, such as circulation or green infrastructure, or a policy, such as agricultural preservation or housing. A functional master plan amends the General Plan but does not make land use or zoning recommendations.

Functional Classification

  • Alley: A right-of-way intended to provide secondary service access to the rear or side of lots or buildings and not intended for transporting through traffic. An alley may be used to provide primary vehicular access if the Planning Board and the Director of Transportation concur that the dimensions and specifications proposed in a project, preliminary subdivision, or site plan would provide adequate primary vehicular access.
  • Arterial: A road meant primarily for through movement of vehicles at a moderate speed, although some access to abutting property is expected.
  • Business District Street: A road meant for circulation in commercial and mixed-use zones.
  • Controlled Major Highway: A road meant exclusively for through movement of vehicles at a lower speed than a Freeway.Access must be limited to grade-separated interchanges or at-grade intersections with public roads.
  • Country Arterial: An arterial, typically in the County’s Agricultural Reserve.
  • Country Road: A road that has the function of a Primary Residential Street, typically in theCounty’s Agricultural Reserve.
  • Freeway: A road meant exclusively for through movement of vehicles at a high speed. Access must be limited to grade-separated interchanges.
  • Industrial Street: A road meant for circulation in industrial zones.
  • Major Highway: A road meant nearly exclusively for through movement of vehicles at a moderate speed.Access must be primarily from grade-separated interchanges and at-grade intersections with public roads, although driveway access is acceptable in urban and denser suburban settings.
  • Minor Arterial: A two-lane arterial meant nearly equally for through movement of vehicles and access to abutting property.
  • Parkway: A road meant exclusively for through movement of vehicles at a moderate speed with access limited to grade-separated interchanges and at-grade intersections.
  • Primary Residential Street: A road meant primarily for circulation in residential zones, although some through traffic is expected.
  • Principal Secondary Residential Street: A Secondary Residential Street meant to carry somewhat more through traffic.
  • Rustic Road: A road that is located in an area where natural, agricultural, or historic features are predominant, and where master planned land use goals and zoning are compatible with a rural/rustic character;is narrow and intended for predominantly local use; is low volume with traffic that does not detract significantly from the road’s rustic character; and has outstanding natural features along its borders, such as native vegetation, tree stands, stream valleys.
  • Secondary Residential Street:A road meant to provide access between a residential development with fewer than 200 dwelling units and one or more higher classification roads.
  • Tertiary Residential Street: A road meant to provide direct access to a residential development with 75 or fewer dwelling units.A Tertiary Residential Street must not be built unless the Planning Board allows its use when the Board approves a preliminary subdivision plan or site plan.


Geographic Information Systems (GIS): The computerized mapping of data that can generate high quality maps based on the analysis of layers of geographic information. GIS allows all information in a database to be integrated for any location covered by the database. The Planning Department uses GIS software to create maps of the communities it serves, to profile existing conditions in those communities, and to analyze population and other relevant data.

Grade separation: Physical separation of two or more transportation facilities, such as roads, bikeways, and rail lines, at their intersection by constructing them so that one facility passes above or below the other.

Grandfathered: Describes the status accorded to certain properties, uses, and activities that may legally continue because they existed prior to the adoption date of changes to the Zoning Ordinance.

Green infrastructure:The interconnected network of natural areas (forests, 100-year floodplains, wetlands, meadows, streams and their buffers) and parks that conserves natural ecosystem values and functions.

Greenway: See Street Character, Functional Classifications, and Road Code Designations

Groundwater: Subsurface water from which wells and springs are fed and that provides the base flow of streams.

Growth Policy: A policy document adopted every other year by the County Council that is intended to facilitate and coordinate the government’s powers in limiting or encouraging growth and development within master plan and zoning limits. It includes criteria and guidance for the administration of the Adequate Public Facilities Ordinance (APFO). The primary purpose of the Growth Policy is to match the timing of private development with the availability of public services.

The Growth Policy is prepared by the Planning Board based on data collected through administration of the Adequate Public Facilities Ordinance and through population and housing projections, and is coordinated with the Executive’s Capital Improvements Program. The Planning Board Draft Growth Policy is transmitted to the County Council. The Council, after a public hearing, must adopt by resolution any changes to the Growth Policy by November 15 of every odd-numbered year.

Guidelines: A set of limits and objectives, less binding than regulations that are used to guide development or plan proposals.


Headwater: The upper reaches of a stream near its source or the region where groundwater emerges to the surface to form a surface stream.

High-Occupancy Vehicle (HOV): A passenger vehicle containing more than one person. This can include cars, vans, and buses.

Historic Preservation Commission (HPC): A nine-member board whose members are appointed by the County Executive and approved by the County Council charged with identifying historic resources in the County that warrant protection and reviewing requested changes to those historic resources.

Historic District: Two or more historic resources that are significant as a cohesive unit and reflect the County’s historic, architectural, archeological, or cultural values.

Historic Resource:A building, structure, object, or area of land that is significant in County history, architecture, archaeology, or culture.

Housing Opportunities Commission (HOC): A Montgomery County, Maryland-based nonprofit organization that provides affordable housing and supportive services.


Impact Tax: A charge collected by the Montgomery County Department of Permitting Services to help pay the costs of providing public facilities in designated areas. The tax is collected at the time of building permit.

Impervious Surface: Any surface that prevents or significantly impedes the infiltration of water into the underlying soil, including structures, buildings, patios, decks, sidewalks, compacted gravel, pavement, asphalt, concrete, stone, brick, tile, swimming pools, and artificial turf.Impervious surface also includes all areas used by or for motor vehicles or heavy commercial equipment, regardless of surface type or material, including roads, road shoulders, driveways, and parking areas.

Industrial Street: See Street Character, Functional Classifications, and Road Code Designations

Infill Development: Development that takes place on vacant or underutilized parcels within an area that is already developed and has access to existing urban services.

Infrastructure: The built facilities, generally publicly funded, that are required to serve a community’s development and operational needs. Infrastructure includes roads, water supply systems, and sewer systems.

Intercounty Connector (ICC): A highway project currently under construction that will connect the areas between the I-270 and I-95/US Route 1 corridors within central and eastern Montgomery County and northwestern Prince George’s County.

Intensity: The gross (total) floor area and/or the degree to which land uses generate traffic, noise, air pollution, and other potential impacts.


Jobs-Housing (j-h) Ratio: The balance between the number of jobs and the number of housing units. The ratio is calculated by dividing the total number of jobs by the total number of housing units in a given area. The jobs-housing ratio measures the opportunity to live near work and thus reduce commuting miles.



Landscaping Plan: A plan, drawn to scale, that shows proposed site design focusing on the location, number, size, species, and distribution of landscape elements including trees, shrubs, and lawn areas, as well as pedestrian paths and open spaces. Any area that is to be counted towards reforestation must be shown on a forest conservation plan.

Land Use: The types of buildings and activities that exist in an area or on a specific site. Zoning regulates existing and future land uses.

Land Use Plan: The land use element of an approved and adopted general, master, sector, or functional plan.

Leadership in Energy and Environmental Design (LEED) Certification: The certification program and nationally accepted benchmark for the design, construction, and operation of high performance green buildings.

Life Sciences Center: An area intended to serve as a unique reinforcing focus of life sciences research, including but not limited to biological, biophysical and bioelectronics research, development, and manufacturing activity. Health care services may also be provided. Must be designated as such on an approved and adopted master plan or amendment thereto.

Light rail transit: An electric railway system characterized by its capacity to operate single cars or short trains along exclusive rights-of-way at ground level, on aerial structures, in subways, or on streets.

Local Area Transportation Review (LATR): Part of the Adequate Public Facilities test used to determine if a proposed development will produce detrimental traffic impacts that go beyond the capacity of existing and programmed roadways and intersections in the vicinity of the site.

Local Map Amendment: A change of zoning for a property, typically sought by a property owner or other person having proprietary interest. A local map amendment can include more than one tract of land which can be combined for the purpose of rezoning.

Locational Atlas and Index of Historic Sites: A historical site inventory used as a guide to prepare amendments to the Master Plan for Historic Preservation.


Main Street: See Street Character, Functional Classifications, and Road Code Designations

Major Highway: See Street Character, Functional Classifications, and Road Code Designations

Mandatory Referral: Under the Regional District Act “no road, park, or other public way or ground, no public (including federal) buildings or structure, and no public utility whether publicly or privately owned shall be located, constructed, or authorized in the regional district until and unless the proposed location, character, grade and extent thereof has been submitted to and approved by the Maryland-National Capital Park and Planning Commission.” (Art. 28, #7-112 of the Regional District Act).

One of the purposes of this review authority is to assure that public land acquisition and development are compatible with surrounding development, both existing and planned. Because the Regional District Act allows agencies to overrule the Commission’s recommendations, a mandatory referral results in recommendations that are not binding on the public agency however, it provides an opportunity to encourage the agency to modify their proposals, where necessary, in order to improve their compatibility. For projects that require the approval of a Forest Conservation Plan or a Water Quality Plan, the mandatory referral review may be reviewed by the Planning Board immediately following those approvals.

Maryland-National Capital Park and Planning Commission (M-NCPPC): A bi-County agencycreated by the General Assembly of Maryland in 1927. The Commission’s geographic authority extends to the great majority of Montgomery and Prince George’s Counties; the Maryland-Washington Regional District (M-NCPPC planning jurisdiction) comprises 1,001 square miles, while the Metropolitan District (parks) comprises 919 square miles, in the two counties. The Commission is responsible for managing physical growth and planning communities, protecting natural, cultural and historic resources, and providing leisure and recreational experiences through the acquisition, development, operation, and maintenance of a public park system. Certain municipalities within the County (e.g. Rockville and Gaithersburg) are outside of the regional district and have their own planning and zoning powers.

Massing describes the relationship of the building’s various parts to each other. Architectural elements such as windows, doors and roofs as well as interior floor plans can affect building mass. Massing is important because it is one of several details that determine the visual interest of a building, the perception of the building’s volume and how it blends with its surroundings.

Master Plans: Comprehensive amendments to the General Plan for the Maryland-Washington Regional District (“On Wedges and Corridors”) that provide detailed and specific land use and zoning recommendations for specific areas of the County. They also address transportation, the natural environment, urban design, historic resources, public facilities, and implementation techniques.

Master Plan for Historic Preservation: A document listing properties protected by the County’s Historic Preservation Ordinance, Chapter 24A of the Montgomery County Code. Listed properties have been approved for designation by the Historic Preservation Commission, the Planning Board, the County Executive, and the County Council. Any proposals for exterior alteration, new construction, subdivision, or demolition of these properties must be reviewed by the Historic Preservation Commission.

Maximum Expansion Limits (MEL): Boundaries established by municipalities that define where future annexations of unincorporated land may occur.

Metropolitan-Washington Council of Governments (MWCOG): The regional organization of the Washington area’s major local governments and their governing officials. MWCOG works toward solutions to such regional problems as growth, transportation, housing, air pollution, water supply, water quality, economic development and noise, and serves as the regional planning organization for the Washington metropolitan area.

Minor Arterial: See Street Character, Functional Classifications, and Road Code Designations

Mixed-use development: The integration of different, usually compatible or mutually supportive, land uses on a site. Uses may share parking and access.

Mixed Use Streets: See Street Character, Functional Classifications, and Road Code Designations

Modal split: The percent of persons arriving at a destination by one of the available transportation modes. For example, the percent of persons who arrive at a destination by private automobiles is called the “auto mode split” and includes both drivers and passengers.

Mode choice: An estimate of the percentage of trips taken in each available transportation mode for each origin and destination pair used to forecast transportation demand. Mode choice analysis is the third step in the conventional four-step transportation forecastingmodel, following trip generation and trip distribution but before route assignment. Mode choice analysis allows the modeler to determine what mode of transport will be used, and the resulting modal share.

Moderately Priced Dwelling Unit (MPDU) Program: First implemented in Montgomery County, Maryland in the early 1970s, an inclusionary zoning/affordable housing programrequiring a certain percentage of housing units built in residential developments of 20 units or more be affordable, i.e. capable of being purchased or rented by those making less than the County’s median income. (Codified in Chapter 25A of the Montgomery County code).

Montgomery County Council: The County’s elected legislative body that has final authority, sitting as the (Regional) District Council, on all matters pertaining to planning and zoning. There are nine members elected to four-year terms. Five represent districts and four are elected at-large.

Multifamily Housing: A building or complex of buildings each containing three or more dwelling units or apartments. Units usually do not have the private, ground-level outdoor space that is required for townhouses.


Natural Resources Inventory (NRI): The collection and presentation of a property’s environmental information according to the guidelines in the adopted Forest Conservation Regulations (COMCOR 18-01 AM) and in the latest version of Environmental Management of Development in Montgomery County, Maryland (M-NCPPC). Environmental information includes topography, steep slopes, perennial and intermittent streams, major drainage courses, 100-year floodplains, wetlands, soils and geologic conditions, critical habitats, aerial extent of forest and tree cover, and necessary buffers. The inventory also includes any cultural features and historic sites.

Network: When referring to transportation, one or more roadways evaluated or analyzed together; in general, a set of transportation facilities. It can refer to a modal network (bicycle, pedestrian, transit, or auto networks) or the network inclusive of all modes.

Node:- A physical focal point of a community activity, often an intersection of roads or a concentration of buildings.

Nonconforming use or building: A use or building that was lawful when established and continues to be lawful, but no longer conforms to the requirements of the zone in which it is located because of the adoption or amendment of the Zoning Ordinance or the Zoning Map.


Optional Method of Development: A zoning procedure used in Central Business District (CBD), Residential mixed-use (RMX) and Transit mixed use (TOMX and TMX) zones that encourages land assembly and mixed-use development. Under the optional method, higher densities are allowed in exchange for significant public amenities and facilities to support that additional density.

Overlay Zone: A mapped zone that imposes a set of requirements or restrictions in addition to those of the underlying zoning district (base zone). Land is developed under the conditions and requirements of both the base zone and the overlay zone.


Paper Street: A dedicated public right of way for a road or street that has not been built.

Parkway: See Street Character, Functional Classifications, and Road Code Designations

Park-and-ride lots: Parking lots that allow all-day commuter parking enabling the auto driver to connect with carpools or transit.

Proposed Park Acquisition Line: A generally designated boundary line for recommended parkland acquisitions that may involve purchase agreements or dedications through the development approval process.They are normally established in master plans.The proposed park acquisition lines are recorded on the Geographic Information System (GIS) system after a master plan has been approved and adopted.

Parking Lot Districts: Areas designated (in Bethesda, Silver Spring, Wheaton, and Montgomery Hills) in which businesses have the option to pay a fee in lieu of providing the Zoning Ordinance’s required off-street parking. The funds are administered by the County Department of Transportation and used to provide public parking facilities.

Peak-hour Trips: Trips made during the busiest hour within the morning and evening peak periods using any transportation mode. For the purposes of development review in Montgomery County, the peak periods are from 6:30 a.m. to 9:30 a.m. and from 4:00 p.m. to 7:00 p.m. during weekdays.

Permeability: The ability of surface soils or materials to permit the movement of water through them when they are saturated.

Pipeline of approved development: See Development Pipeline

Planned Development Zone (PD): This zone has fewer specific requirements and restrictions than other zones, which allows for greater flexibility of design and use, subject to a binding plan proposed by the applicant and approved by the Planning Board that spells out land uses, setbacks, housing densities, land coverage, building spacing, landscaping, building heights, open space, and other elements.

Policy Area: A geographic sub-area of the County delineated by the Planning Board and adopted by the County Council in the Growth Policy for the purpose of staging analysis and the establishment of transportation staging ceiling capacities.

Policy Area Mobility Review (PAMR) – A transportation test for the Growth Policy that measures levels of service for transit and arterial travelers (LOS) to help determine an appropriate rate and level of growth.

Pre-preliminary Subdivision Plan: An optional step in the subdivision process that allows an applicant to submit a conceptual plan to determine whether a site is suitable for development. The plan can be submitted for staff review only or can go before the Planning Board for either a binding or non-binding decision.

Preliminary Plan: A plan for a proposed subdivision or resubdivision of land submitted under Chapter 50, Subdivision, of the Montgomery County Code. The plan is reviewed by staff and submitted for action (approval or disapproval) by the Montgomery County Planning Board. Board approval of the plan is necessary prior to preparation of a record plat.

Primary Residential Street: See Street Character, Functional Classifications, and Road Code Designations

Principal Secondary Street: See Street Character, Functional Classifications, and Road Code Designations

Priority Funding Area: Maryland communities and places, designated by the Smart Growth Priority Funding Areas Act of 1997, where State resources will be focused to encourage future growth.

Program Open Space (POS): A State fund that provides technical and financial support to local governments for the planning, acquisition and/or development of recreation land or open space areas, including dedicated funding for Maryland’s state and local parks and conservation areas. Recreational areas or open spaces that were acquired or developed using POS funding cannot be converted into other uses without receiving approval from the Secretary of the Maryland Department of Natural Resources, the Secretary of the Department of Planning, and the Secretary of the Department of Budget and Management and without replacing proposed converted land with land of at least equivalent area and of equal recreation or open space value.

Programmed Facility: A capital facility project of which 100 percent of the expenditures for construction or operation are budgeted within the applicable capital program. The projects are contained within the County’s approved Capital Improvements Program (CIP), the State Consolidated Transportation Program (CTP), or capital programs of Rockville or Gaithersburg.

Project Plan: Required in certain zones where an applicant is requesting increased density in exchange for additional public or open space or amenities. Project plans are required in Central Business Districts and areas where increased density warrants the provision of additional public facilities and amenities. They are expected to show conformance with applicable master plans and may be approved, approved with conditions, or denied by the Planning Board.

Public Use Space: Space devoted to uses for public enjoyment, such as gardens, plazas, or walks. This space does not include areas for parking or maneuvering vehicles. The CBD Zones require development projects to provide both increased public use space and increased public facilities and amenities to earn optional method densities.

Purple Line: A proposed 16-mile rapid transit line extending from Bethesda, Maryland (Montgomery County) to New Carrolton, Maryland (Prince George’s County). The Purple Line will connect directly to the Metrorail Red, Green, and Orange Lines.



Record Plat: A plan drawing that depicts an approved subdivision or assemblage of land and associated easements or restrictions. It is recorded in the land records of Montgomery County.

Receiving Area: An area designated on an approved and adopted general, master, sector, or functional plan as appropriate for development beyond its base density through the transfer of development rights (TDRs and BLTs).

Regional District Act: An act of the Maryland State Legislature that assigns responsibility for planning, zoning, and subdivision to the Maryland-National Capital Park and Planning Commission of Montgomery and Prince George’s Counties. Seven municipalities in Montgomery County are not covered by this act: Rockville, Laytonsville, Gaithersburg, Barnesville, Poolesville, Brookeville and Washington Grove.

Resubdivision: A change in any lot line of a recorded lot or parcel of land. Resubdivision includes the assembly of recorded lots or parts of lots. A resubdivision is a subdivision.


  • Public: A strip of land intended for travel by the public. A public right-of-way is occupied or intended to be occupied by a road, bikeway, sidewalk, path, or transit facility, as well as any ancillary facilities such as storm drains and stormwater management facilities. Public utilities such as electric transmission lines, telephone lines, cable TV lines, gas mains, water mains, and sanitary sewers may be permitted in the public right-of-way. A public right-of-way may be obtained by dedication as part of the development process or purchased in whole or in part by a public agency.
  • Private: A strip of land intended for travel and owned by a private person, group of persons, or corporation, or intended for use by a major utility. A private right-of-way may be occupied or intended to be occupied by a road, bikeway, sidewalk, path, or railroad. A private right-of-way may also be occupied or intended to be occupied by an electric transmission line, oil or gas pipeline, other utility, or for other special use. A private right-of-way must be shown on a record plat as separate and distinct from the adjoining lots or parcels and not be included within their dimensions.

Road Code: Legislation that addresses road design standards for Montgomery County’s roads (Chapter 49A of the Montgomery County Code).

Road Code Areas

  • Rural Road: A road segment located in a rural policy area as defined in the County’s Growth Policy.
  • Suburban Road: A road segment not otherwise designated as an Urban or Rural road.
  • Urban Road: A road segment in or abutting a Metro Station Policy Area, Town Center Policy Area, or other urban area expressly identified in a Council resolution.

Rustic Road: See Street Character, Functional Classifications, and Road Code Designations


Scenic Easement: A contractual agreement to permanently preserve an area’s visual character.

Secondary Residential Street: See Street Character, Functional Classifications, and Road Code Designations

Sectional Map Amendment (SMA): A comprehensive rezoning, initiated by the Planning Board or County Council, covering a section of the County and usually including several tracts of land. It normally takes place following adoption of a master plan. The County Council must hold a public hearing on a proposed sectional map amendment. Enactment of a sectional map amendment is considered a legislative action of the government and is intended as a comprehensive implementation of public policy; therefore it does not require, as does a local map amendment, a finding of a change in the character of the neighborhood or a mistake in the original zoning.

Sector Plan: A detailed plan for a portion of a master plan area that is adjacent to transit or covering a central business district or other small area characterized by intense development.

Example of a residential setbackExample of a residential setback (Source: M-NCPPC/Montgomery County Planning Department (2009). “Zoning Discovery”)

Setback: The minimum distance that a building or parking area must be set back from a lot line. Minimum setbacks are specified in some zones, while other zones allow the Planning Board to establish the setbacks, thereby allowing greater flexibility for development.

Site Plan: A detailed plan, required only in certain zones, that shows proposed development on a site in relation to immediately adjacent areas. It indicates roads, walks, parking areas, buildings, landscaping, open space, recreation facilities, lighting, etc. Site plan review is required of all floating zones and of most overlay zones. It is also required in some zones when using optional method of development provisions. Further, certain parking facilities that fall under the provision of the off-street parking section of the Zoning Ordinance are also subject to site plan review. The Planning Board approves the site plan after preliminary subdivision plan approval and before building permits can be issued.

Sketch Plan: An illustrative plan or model that shows the maximum densities for residential and non-residential development, including building massing and height, locations of public use and other spaces, and the relationship to existing and proposed buildings and properties. A Sketch Plan is required for optional methods of development and is intended to provide circulation patterns and description of the public benefits proposed and incentive densities requested, as well as the phasing of the development and public benefits. The Planning Board approves the Sketch Plan prior to Preliminary Subdivision and Site Plan review.

Smart Growth Boundary: See Priority Funding Area

Solid Waste Management Plan: A ten-year plan addressing solid waste disposal systems, solid waste facilities, and solid waste collection and disposal (Subtitle 5, Article 9 of the Environment Article, Annotated Code of Maryland). The Plan is adopted by the Montgomery County Council and approved by the Maryland Department of the Environment, and is updated every three years.

Special Exception: A use that is not allowed by right in a given zone but which may be allowed if certain conditions are met (as detailed in Article 59-G of the Montgomery County Code). Special exceptions require a request for permission and a grant of approval by the Montgomery County Board of Appeals. The use must also be found to be consistent with the applicable master plan and compatible with the existing neighborhood.

Special Protection Area (SPA): A geographic area where existing water resources and related environmental features are of high quality or unusually sensitive, and proposed land uses would threaten the quality or preservation of those resources if special water quality protection measures, closely coordinated with land use controls are required to prevent proposed land uses from threatening the quality or preservation of those resources. SPAs are designated by the County Council under Section 19-62(a) of the Montgomery County Code.

Specimen Tree: A tree that is a particularly impressive or unusual example of a species due to its size, shape, age, or any other trait that epitomizes the character of the species.

Staging Plan: A plan that guides the sequence of development based on public policies, existing or planned infrastructure, market projections, trigger events, or funding. It may address land development strategies or organizational mechanisms, such as transportation management districts, capital improvements, or other public or private investments. The staging plan need not be date specific (also called a Phasing Plan).

Standard Method of Development: A development method in which property is developed according to written standards of the Zoning Ordinance, without using the Optional Method of Development (See Optional Method of Development).

Stormwater Management: The collection, conveyance, storage, treatment and disposal of stormwater runoff to prevent accelerated channel erosion, increased flood damage, and degradation of water quality.

Stream Valley Buffer: See Environmental Buffer

Street Character, Functional Classifications, and Road Code Designations: Street character describes how roadway features should be designed to integrate the public and private realm. Functional classifications describe the roadway’s purpose—the degree to which its primary function is to provide access to adjacent land uses or mobility for longer-distance travel. Functional classification is described in Section 49-31 of the County Code.

Street Character:

  • Boulevard: A multiple lane, divided roadway that carries significant through traffic and local traffic and is often classified as a highway or arterial. Driveway access to individual businesses is limited. Sidewalks are wide to accommodate significant pedestrian activity. Street trees and medians are planted with tall growing shade trees. Examples: Wisconsin Avenue, Bethesda; Georgia Avenue, Silver Spring.
  • Greenway: A street with a recreational function in addition to transportation. Can be two to six lanes with linear parks, bikeways, and other recreational facilities within the public right-of-way. These streets are often classified as highway, arterial, or business district streets. Alternatively, the term is also used to describe linear parks or open spaces where people and animals can travel in areas dominated by natural vegetation. Example: Crystal Rock Drive, Germantown.
  • Main Street: A two to four lane roadway that distributes local traffic and is often classified as an arterial, business district, or primary street. These streets are lined with activating uses such as retail, housing, and office uses. On-street parking, wide sidewalks, street trees, and other special streetscape elements contribute to city life and pedestrian needs. Examples: Woodmont Avenue, Bethesda; Fenton Street, Silver Spring.
  • Mixed-Use Street: Streets that emphasize pedestrian circulation while allowing for limited slow auto traffic. Trees, bollards, and street furniture are used to mark the pedestrian domain. Example: Ellsworth Drive, Silver Spring.
  • Promenade: A special street with a wide linear sidewalk/public space that functions as a social gathering place activated with restaurants, cafes, retail, and other uses. On-street parking, wide sidewalks, street trees, and other special streetscape treatment are required to define the special character and public space function. Example: Rockville’s Town Center.
  • Transitway: A right-of-way for transit service such as light rail or rapid bus. Transit vehicles can be located within a median, within lanes or to the side of vehicle lanes. Station locations are key destinations within a community. Example: Corridor Cities Transitway, I-270 Corridor

Streetscape: The environment of the street right-of-way as defined by adjacent private and public buildings, pavement character, street lighting and street furniture, and the use of the right-of-way.

Structured Parking: An above-ground or below-ground parking garage.

Subdivision: The division or assemblage of a lot, tract, or parcel of land into one or more lots, parcels, or other divisions for the purpose, whether immediate or future, of sale, lease, or building development.

Systemic Safety: An approach to safety that involves widely implemented improvements based on high-risk roadway features correlated with specific severe crash types. Represents a shift from reacting to locations with a history of crashes to proactively installing improvements.


Tax Increment Financing (TIF): A land development financing tool to promote economic development at the local government level by earmarking property tax revenue from increases in assessed values within a designated district for the provision of infrastructure needed within that designated district.

Tertiary Residential Street: See Street Character, Functional Classifications, and Road Code Designations

Traffic Analysis Zone (TAZ): The County is currently divided into 318 geographically distinct areas defined by natural or man-made features. Socio-economic and demographic data for each zone are analyzed to help estimate transportation demand.

Traffic Calming: Physical changes to a street or roadway used to improve safety by decreasing traffic speed and volume. Methods of traffic calming include traffic circles, speed humps, and curb extensions.

Traffic Mitigation Agreement: A legal agreement between the Planning Board, County government, and a private developer to implement traffic mitigation measures that achieve or help achieve an established trip reduction goal.

Transferable Development Right (TDR): The conveyance of development rights, as authorized by local law, to another parcel of land and the recordation of that conveyance among the land records of Montgomery County.

Transit Accessible: An area or development within a reasonable walking distance of bus routes and rail service.

Transit Group Classification: In the Growth Policy, an index (I to VI) classifying policy areas according to transit service availability. The higher the number, the greater the transit availability. More traffic congestion is considered acceptable in areas with transit alternatives.

Transit Mode Share: Trips made by mass transit as a percentage of all trips made, usually measured at the peak hour.

Transitway: See Street Character, Functional Classifications, and Road Code Areas

Transit-Oriented Development (TOD): A transit-oriented development is a mixed-use community
within a quarter-mile to half mile walking distance of a transit stop and commercial area. TODs have sufficient development density to support frequent transit service and a mix of residential, retail, office, and public uses in a walkable environment, making it convenient for residents and employees to
travel by transit, bicycle, or foot.

Transportation Demand Management (TDM): A range of programs and services designed to reduce the use of single-occupant vehicle trips, particularly during periods of peak travel. TDM strategies provide travel options that reduce and spread demand by travel destination, mode, route, and time of day to most efficiently use transportation system infrastructure and resources.

Transportation Management District (TMD): A designated area established by local legislation that attempts to mitigate traffic congestion through a combination of public and private sector measures to improve transportation facilities and services, and reduce travel demand.

Transportation Management Organization: The organization established by County legislation that implements master-planned trip reduction goals through a combination of public and private sector measures to improve operation of transportation facilities and services, and reduce travel demand.

Transportation Policy Area Review (TPAR): Measures the impacts of development on traffic flow and transit capacity in each of the county’s 30 traffic policy areas. TPAR establishes standards for roadway and transit adequacy and determines which policy areas meet those standards. If development is proposed in a policy area that does not meet the roadway or transit standards, the development must provide the needed capacity or make a TPAR payment.

Tree Save Plan (TSP): A plan approved by the Planning Board under Chapter 22A or Chapter 50 of the County Code, which covers individual trees or stands of trees to be saved as part of, or instead of, a forest conservation plan.

Trip Generation: The number of one-way trips to or from a location as a result of land use activity at that location.

Trip Mitigation: Reduce congestion during peak commuting hours by encouraging travelers to use alternatives to driving alone, especially at the most congested times of the day. Alternatives include carpools, vanpools, public and private transit, bicycling, walking, compressed and flexible work schedules, and telecommuting.

Trip Reduction Agreement: Similar to a Traffic Mitigation Agreement but used in unique applications to satisfy I-3 trip reduction goals for developments on I-3 zoned property.


Urban Design: The process of giving form, shape, and character to the arrangement of buildings on specific sites, in whole neighborhoods, or throughout a community. Urban design blends architecture, landscaping, and city planning concepts to make an urban area accessible, attractive, and functional.

Example of Urban Design: Pedestrian-oriented street network

Example of Urban Design: Pedestrian-oriented street network (Source: Draft Urban Design Guidelines for the Germantown Employment Area Sector Plan (2009))

Urban District: A County special purpose tax area for an urban location to develop and maintain communities that contain diversified commercial, residential and institutional development. An urban district is intended to provide streetscape maintenance and public amenities, promote commercial and residential interests of the area within the district’s boundaries, provide cultural and community activities, enhance and monitor the safety and security of the public and property, and provide any capital project that promotes the economic stability and growth of the district. Montgomery County’s urban districts are in Bethesda, Silver Spring, and Wheaton.

Urban Growth Boundary: Fixed geographic lines that identify when and where land will become available for development.


Variance: Permission, granted by the Board of Appeals, to depart from the literal requirements of a zoning ordinance. A variance cannot be contrary to public interests and must be based on findings that there are conditions specific to the property that prevent strict application of the regulations, that the variance from the regulations is the minimum relief necessary, that the variance causes no impairment to master plan goals, and that the variance is not detrimental to adjacent property.


Vision Zero: A strategy to eliminate all transportation fatalities and severe injuries. Vision Zero starts with the ethical belief that everyone has the right to move safely in their communities, and that system designers and policy makers share the responsibility to ensure safe systems for travel.


Watershed: The area within a topographic divide above a specified point on a stream that drains into that stream. The watershed boundaries in Montgomery Country correspond with the sub-basins defined in water quality regulations adopted by the Maryland Department of the Environment under Maryland State Code (COMAR)

Water Quality Plan: A plan that indicates how the high quality or unusually sensitive water resources and environmental features in designated Special Protection Areas will be preserved or maintained within designated special protection areas.

Wedges and Corridors: A pattern of development set by the 1964 General Plan for Montgomery County that divides the region into a series of developed corridors along major roadways, and low density, residential or agricultural wedges in the intervening areas.

Wetland: An area inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, under normal circumstances, a prevalence of vegetation typically adapted for life in saturated soil conditions.

Workforce Housing: Housing provided pursuant to Chapter 25B of the Montgomery County Code that is intended to be affordable to households earning between 80 and 120 percent of the area-wide median income. The workforce housing requirements apply to subdivisions of 35 or more dwelling units in a zone with a maximum permitted density of at least 40 dwelling units per acre and in a Metro Station Policy area. Workforce Housing is intended to complement the MPDUs required by Chapter 25A.


Zone: A classification intended to regulate the land uses and buildings that are permitted in an area. Within each zone, certain uses are permitted by right and others conditionally by special exception. Any use not expressly permitted is prohibited.

Zoning: The division of a locality into zones for the purpose of regulating the use of private land. All land in Montgomery County is zoned. Within each zone, the County Zoning Ordinance permits certain uses by right and allows others conditionally through special exception. The Ordinance also excludes or limits certain uses from each zone. Within each of these zones, the text of the Zoning Ordinance specifies the permitted uses, the bulk of buildings, the required yards, the necessary off-street parking, and other prerequisites to obtaining permission to develop. The County Council, acting as the District Council, makes final decisions on the application of both Euclidean and floating zones.

Maryland law permits the use of two types of zones, Euclidean and floating zones. There are important distinctions between the two that affect the manner in which they can be employed.

  • Euclidean zones: A Euclidean zone contains fixed standards. Certain uses are permitted by right in these zones, but they are subject to rigid requirements such as lot size; front, side and rear setbacks; and maximum height. Application for a Euclidean zone may be made either by the property owner (through a Local Map Amendment) or by the government (through a Local Map Amendment or a Sectional Map Amendment). Maryland law provides that a local map amendment rezoning to a Euclidean zone is permissible only if there has been a change in the planned character of the neighborhood since the last comprehensive rezoning or a mistake in the original zoning.
  • Floating zones: A floating zone is more flexible, and the County Council must find that the proposed zone is compatible with the surrounding area and that the proposed development meets the purposes of the zone. Findings of change or mistake, required for approval of a Euclidean zone, do not have to be made before the application for a floating zone can be granted. Some floating zones require affirmative master plan recommendations.

Zoning Map: The official map showing the location of all zoning categories in a given area.

Zoning Map Amendment: A change in the zoning designation of a property or area. This may be done on a piecemeal basis through a Local Map Amendment or comprehensively by the County Council through approval of a Section Map Amendment.

Zoning Text Amendment: A legislative change to the text of the Zoning Ordinance.

Last Updated: March 12, 2021