Morrisville Unified Development Ordinance

Article 11: Interpretation and Definitions Section 11.5. Terms and Uses Defined 11.4.3. Illuminated Signs

L OW I MPACT D EVELOPMENT A manner of land development that seeks to protect waterways, habitat, baseflow, and groundwater recharge. Low Impact Development also protects water quality by minimizing the pollutant loading to waterways from developed areas. L OW S OLAR G AIN /L OW E MITTANCE (L OW E) W INDOW Low solar gain, low-emittance (Low-E) refers to windows designed to suppress radiative heat transfer through the use of a microscopically thin, virtually invisible, metal or metallic oxide layer coating, reducing heat loss in winter and heat gain in summer. L OWEST A DJACENT G RADE (LAG) For purposes of floodplain management, the elevation of the ground, sidewalk or patio slab immediately next to the building, or deck support, after completion of the building. L OWEST F LOOR For purposes of floodplain management, the lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure usable solely for parking of vehicles, building access or limited storage in an area other than a basement area is not considered a building's lowest floor provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of this article. L UMEN A quantitative unit measuring the amount of light emitted by a light source. A lamp is generally rated in lumens. LUX A unit of illuminance on a surface one meter from a uniform point source of light of one candle and equal to one lumen per meter. (1 LUX = 0.0929 foot-candle) M AIN S TREET Specialized accessways that primarily function to accommodate pedestrian access to and within concentrations of higher intensity retail and mixed land uses, such as the Town Center and activity center districts. They are designed with attractive pedestrian-friendly streetscapes that promote walking, bicycling, and transit. To accommodate high pedestrian activity, they generally provide limited direct driveway access to abutting development, relying instead on side street access to rear parking facilities. M AINTAINED F OOT -C ANDLES Illuminance of lighting fixtures adjusted for a maintenance factor accounting for dirt build-up and lamp output depreciation. The maintenance factor used in the design process to account for this depreciation cannot be lower than 0.72 FC for high-pressure sodium and 0.64 FC for metal halide and mercury vapor. M AJOR T HOROUGHFARE An accessway that primarily functions to channel intercity vehicular traffic to and through the Town and to provide trave l mobility among the Town’s major activity centers by connecting minor thoroughfares with each other and with collector streets. It handles moderate to high travel speeds and traffic volumes over relatively long distances, and provides limited direct driveway access to abutting development.

Morrisville, NC

October 1, 2021

Unified Development Ordinance

Page 11-52

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