Elevation Benchmarks (Vertical Survey Control Points)

This is a point data set representing monumented vertical geodetic survey control points (a.k.a. elevation benchmarks) established by the City of Boise. A benchmark is a physical marker, monument, or demarcation established by a surveyor for horizontal and/or vertical measurement control. This data set only contains benchmarks established by the City of Boise that are based on the North American Vertical Datum of 1988 (NAVD 88); benchmarks established under other vertical datums are not included. The elevation values in this data set are based on the vertical control from the National Geodetic Survey (NGS), the U. S. Geological Survey (USGS), and some state owned vertical control. The horizontal location is obtained by Global Positioning System (GPS) data collection of the surveyed benchmark. Attribute data including elevation, is transcribed from surveying field books supplied by Boise City Public Works survey personnel. Data Attributes: MARK TYPE: ALCAP - Aluminum Cap, BRASSCAP - Brass Cap, CHISELSQ - physically carved square, PK - A steel masonry nail manufactured by Parker Kaelon (PK nail), OTHER - Any other survey marker type. LOCATION: Nearest street or cross streets to the benchmark. ELEVATION: The vertical elevation in feet above sea level as established from survey calculations based on the 1988 NAVD Datum. GPS DATE: Date the benchmark was captured by GPS. COMMENTS: Pertinent notes on general description and location of the benchmark. BOOK: The City of Boise Public Works surveying field book number the benchmark was established under. PAGE: The City of Boise Public Works surveying field book page the benchmark was established under. The data set is maintained by the Boise City Public Works GIS staff. The data is updated continuously. It is current to the date it was published. For more information, please visit Ada County Control Information or City of Boise Public Works.本数据集为博伊西市设立的标石式垂直大地测量控制点（vertical geodetic survey control points），亦称高程基准点（elevation benchmarks）。基准点是测量员为水平和/或垂直测量控制所设立的实体标记、标石或界址标识。本数据集仅包含博伊西市基于1988年北美垂直基准面（North American Vertical Datum of 1988，NAVD 88）设立的基准点，未纳入其他垂直基准面下设立的基准点。 本数据集的高程值基于美国国家大地测量局（National Geodetic Survey，NGS）、美国地质调查局（U. S. Geological Survey，USGS）的垂直控制基准，以及部分州属垂直控制基准。该基准点的平面位置通过对已测量基准点的全球定位系统（Global Positioning System，GPS）数据采集获取。包括高程在内的属性数据均由博伊西市公共工程局测量人员提供的测量外业手簿转录而来。 ### 数据属性说明： - 标记类型（MARK TYPE）：ALCAP（铝制标记帽）、BRASSCAP（黄铜制标记帽）、CHISELSQ（手工雕刻方形标记）、PK（帕克·基隆（Parker Kaelon）生产的钢制砖石钉，简称PK钉）、OTHER（其他类型测量标记） - 位置（LOCATION）：基准点附近的街道或交叉路口名称 - 高程（ELEVATION）：基于1988年北美垂直基准面通过测量计算得出的海拔高程，单位为英尺 - GPS采集日期（GPS DATE）：基准点通过GPS完成数据采集的日期 - 备注（COMMENTS）：关于基准点基本信息与位置的相关说明 - 手簿编号（BOOK）：该基准点设立时所属的博伊西市公共工程局测量外业手簿编号 - 手簿页码（PAGE）：该基准点设立时所属的博伊西市公共工程局测量外业手簿页码 本数据集由博伊西市公共工程局地理信息系统（Geographic Information System，GIS）工作人员维护，数据持续更新，发布当日数据为最新有效状态。如需更多信息，请访问埃达县基准控制信息页面或博伊西市公共工程局官网。