Loudoun Street Centerline

More Metadata Data updated daily. Street centerline was originally developed from the road features on the County's 1:2400 base map. Both address range and a link to street names are included as data attributes. The current data is collected from recorded plats in DXF format or is digitized from plats. The data covers the entire County as well as the incorporated Towns. Purpose: The street centerline coverage was originally developed to support addressing. Fire & Rescue Services and the Sheriff's Office use the address range information for Emergency 911 dispatching; it is also used to update U.S. Census Bureau Tiger data in support of the decennial census. Supplemental Information: Centerline data are maintained from plats and site plans prepared by engineering and surveying firms. Although street centerline is the most current of the County's street data, deviation in construction after plat submittal and recordation may cause centerline to differ from similar County layer, road casing. Centerline contains the most current data; road casing is spatially more accurate because it is updated photogrammetrically. These data are not intended to be used for local surveys or at a scale larger than 1:2400. Data are stored in the corporate ArcSDE Geodatabase as a feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN. Maintenance and Update Frequency: Data is updated on a daily basis. Completeness Report: Features may have been eliminated or generalized due to scale and intended use. To assist Loudoun County, Virginia in the maintenance of the data, please provide any information concerning discovered errors, omissions, or other discrepancies found in the data. Data Owner: Office of Mapping and Geographic Information

元数据（Metadata）每日更新。道路中心线（Street centerline）最初源自本县1:2400比例尺底图中的道路要素，数据属性包含地址范围与街道名称关联字段。当前数据集采集自DXF格式的已备案规划图，或通过对规划图数字化获取，覆盖全县及各已设建制城镇区域。应用场景：道路中心线数据集最初为满足地址编码需求开发。消防救援部门与警长办公室可利用地址范围信息开展911应急调度；该数据还可用于更新美国人口普查局（U.S. Census Bureau）的Tiger数据，以支持十年一次的人口普查工作。补充说明：本中心线数据集由工程与测绘公司提交的规划图及场地平面图进行维护更新。尽管道路中心线是本县现有道路数据中时效性最强的数据集，但规划图提交备案后，实地施工产生的变更可能导致中心线数据与本县另一相似图层——道路轮廓（road casing）存在差异。道路中心线数据时效性最佳，而道路轮廓图层的空间精度更高，因其通过摄影测量方式完成更新。本数据集不可用于本地测绘，亦不可在大于1:2400的比例尺下使用。数据集以要素类（feature class）形式存储于企业级ArcSDE地理数据库（ArcSDE Geodatabase）中，坐标系采用弗吉尼亚州平面坐标系（北带），编号4501，基准面为NAD83 HARN。维护与更新频率：数据每日更新。完整性说明：受比例尺与应用场景限制，部分要素可能已被简化或剔除。若您发现本数据存在错误、遗漏或其他不一致之处，请向弗吉尼亚州劳登县（Loudoun County, Virginia）提供相关信息，以协助其完成数据维护工作。数据所有者：测绘与地理信息办公室。