These are locations that are to be used as an elevation reference and contain the official elevation and last known latitude and longitude.

This feature class is maintained to keep construction, mapping and all city services in and adjacent to the city on the same vertical datum. Thus minimizing mistakes or conflicts in construction or maintenance of the infrastructure of the city. This feature class represents the cities vertical control network which was started approximatley in 1971. The oringinal bench mark used to start the network was a NGS (Nationa Geodetic Survey) monument located in the northwest part of the city (Stapleton Airport/Peoria and Smith). Level loops and runs were added and extended as the city grew. Which also incorporated more NGS monuments. The datum used when the program started was NGVD (National Geodetic Vertical Datum) of 1929 . In June of 2006 the city converted from NGVD 1929 to NAVD (North American Vertical Datum) of 1988 using Corpscon 6.0.1 and the Geoid 2003. This network has been successful and should be maintained until a improved alternative can be utilized.

Survey monuments, also called survey marks, survey markers, survey benchmarks or geodetic marks, are objects placed to mark key survey points on the Earth's surface. They are used in geodetic and land surveying.Data are updated by city staff as needed, and automatically copied to the Open Data Portal. The "Last Updated" date shown on our Open Data Portal refers to the last time the data schema was modified in the portal, or any changes were made to this description. We update our data through automated scripts which does not trigger the "last updated" date to change.

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.

Benchmarks are survey markers that provide a point of particular elevation used as a reference for determining elevations of other points in a survey. They are used by surveyors, engineers, planners, and contractors for establishing elevations for planning, designing, and/or construction of various projects.The City of Portland is responsible for establishing and maintaining a network of benchmarks throughout the city, each having a known elevation expressed in feet in the City of Portland’s own datum (established in 1896). Most of the City of Portland’s Benchmarks are brass disks about 2 ½" in diameter, and all are marked "City of Portland Bench Mark No. nnnn " and usually set in the curbs of streets. Occasionally you’ll see larger disks of 3 ¾" diameter which are "Class A" monuments, and some benchmarks are set in retaining walls, bridge wing walls, culvert headwalls, concrete steps, or wherever the most stable and accessible placement was determined to be for a specific location. You might also see benchmarks similar to those of the City of Portland’s but with another governmental agency’s or private firm’s name stamped on it. Occasionally the City of Portland Benchmark Book will refer to these monuments and provide elevations, but more often you’ll have to contact the appropriate institution for more information. The benchmark numbers the City assigned to outside agency monuments are for indexing purposes only; PDOT does not stamp a City of Portland benchmark number on other agencies' monuments.-- Additional Information: Category: Survey Purpose: For mapping and analysis related to the maintenance of survey benchmarks. Update Frequency: As needed-- Metadata Link: https://www.portlandmaps.com/metadata/index.cfm?&action=DisplayLayer&LayerID=53238

The following dataset includes "Active Benchmarks," which are provided to facilitate the identification of City-managed standard benchmarks. Standard benchmarks are for public and private use in establishing a point in space. Note: The benchmarks are referenced to the Chicago City Datum = 0.00, (CCD = 579.88 feet above mean tide New York). The City of Chicago Department of Water Management’s (DWM) Topographic Benchmark is the source of the benchmark information contained in this online database. The information contained in the index card system was compiled by scanning the original cards, then transcribing some of this information to prepare a table and map. Over time, the DWM will contract services to field verify the data and update the index card system and this online database.This dataset was last updated September 2011. Coordinates are estimated. To view map, go to https://data.cityofchicago.org/Buildings/Elevation-Benchmarks-Map/kmt9-pg57 or for PDF map, go to http://cityofchicago.org/content/dam/city/depts/water/supp_info/Benchmarks/BMMap.pdf. Please read the Terms of Use: http://www.cityofchicago.org/city/en/narr/foia/data_disclaimer.html.

This map depicts the locations of survey monuments within and surrounding the City of Salinas, Monterey County, California. Included are National Geodetic Survey (NGS) and city maintained monuments datasets. See NGS website for additional details on NGS monuments. This is not a comprehensive dataset for all survey monuments within the city, additional sources of monuments may be present within the city. City maintained monuments may not be included in the NGS dataset. This service was created by a member of the GIS team in 2017.

This map service contains survey monument layers for the City of Coquitlam.The City of Coquitlam assumes no responsibility with respect to the accuracy, completeness or appropriateness of the data provided. The user is responsible for obtaining their own independent engineering, technical and other advice with respect to any information included in this data, materials or documents provided.Mapping projection: Universal Transverse Mercator. Horizontal datum: NAD83, Zone 10 North, Central Meridian 123 degrees. Vertical datum: Geodetic or the Canadian Geodetic Vertical Datum 1928 (CGVD28 GVRD). Data accuracy varies from 0.05 to 10 metres.

This point feature class contains survey benchmark locations for The City of Pickering. Maintenance and Update Frequency: As NeededDepartment: Engineering ServicesThe City of Pickering does not make any representations concerning the accuracy, likely results or reliability of the use of the materials. The City hereby disclaims all representations and warranties. While great care will be taken to keep this information as up to date as possible we cannot guarantee complete accuracy. For additional details please refer to the most up to date version of The City of Pickering's Licence Agreement.

This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Each geodetic control station in this dataset has either a precise Latitude/Longitude used for horizontal control or a precise Orthometric Height used for vertical control, or both.

The National Geodetic Survey (NGS) serves as the Nation's depository for geodetic data. The NGS distributes geodetic data worldwide to a variety of users. These geodetic data include the final results of geodetic surveys, software programs to format, compute, verify, and adjust original survey observations or to convert values from one geodetic datum to another, and publications that describe how to obtain and use Geodetic Data products and services.

MOA Survey Benchmarks

Location of where survey records are on file.

The benchmark data contains name, type, material, coordinates, elevations and vertical order. All benchmarks were conventionally leveled through in accordance with the procedures setup in the Brevard County Vertical Control Manual (October 2012). The elevations of the bench marks are based on the North American Vertical Datum of 1988 (NAVD88). The horizontal coordinates are from a handheld GPS unit and are fro reference purposes only.

Los Angeles County Department of Public Works’ Vertical Control Network is composed of more than 1,700 miles (2,720 kilometers) of level runs and comprise nearly 9,000 benchmarks. The basic accuracy of the net is reflected by an indicated field probable error of ± 0.017 feet per mile (4 mm per kilometer) of leveling as determined from conditions of closure. However, because of varying degrees of subsidence and heaving, the true datum is recovered only by obtaining substantial agreement of a number of benchmarks.For each active benchmark, a point representation was created in GIS by locating them based on their description. Parcel data, mile markers, the County Address Management System (CAMS), LARIAC aerials, oblique photos, 2-foot contour lines and/or Google Street View were used in assisting with the location.The creation of the benchmarks in GIS greatly enhances the Vertical Control Network by adding visual context with respect to their representative geospatial locations. With a glance, geospatial patterns can be observed and out-of-place benchmarks can be quickly identified and remapped to the correct location after verification.To facilitate the adjustment, indexing and distribution of adjusted values in the network, the county territory was divided into 33 quads or areas. For identification purposes, each quad was given a name (for example, “Rosemead”, “La Mirada”, “Santa Fe”, and etc.). Index maps, county maps, and other information can be accessed and downloaded on the basis of each of the quads by going to Survey Division’s Benchmark Retrieval System (https://pw.lacounty.gov/sur/benchmark). General adjustments are carried out every 5 to 10 years and the provided elevation data is expected to remain sound during this period. When a quad is adjusted, new elevations will be published and the date of the readjustment will be noted. No historical data is provided, but it can be acquired from Survey Division’s Public Records Counter or via the fee based Optional Technical Research (OTR) program. For general questions, contact:Hector Chang626-458-7038hchang@dpw.lacounty.govFor survey-related questions, contact:Charles Springstun626-320-9896cspring@dpw.lacounty.govThe following resources can be used to obtain historical benchmark data:PUBLIC RECORDS COUNTER900 S. Fremont Ave, 4th FloorAlhambra, CA 918037:00 AM to 5:00 PM Mon – ThursPhone: (626) 458-5137OPTIONAL TECHNICAL RESEARCH (OTR)7:00 AM to 5:00 PM Mon – ThursPhone: (626) 458-5131

This web map shows the location of Geodetic Survey Control Stations (Bench Marks) in Hong Kong. It is a subset of the data made available by the Lands Department under the Government of Hong Kong Special Administrative Region (the “Government”) at https://portal.csdi.gov.hk ("CSDI Portal"). The source data has been processed and converted into Esri File Geodatabase format and then uploaded to Esri’s ArcGIS Online platform for sharing and reference purpose. The objectives are to facilitate our Hong Kong ArcGIS Online users to use the data in a spatial ready format and save their data conversion effort.For details about the data, source format and terms of conditions of usage, please refer to the website of Hong Kong CSDI Portal at https://portal.csdi.gov.hk.

Mascot geodetic control monuments for BC. Geodetic Control Monuments are a network of interconnected markers in the ground which have accurately determined coordinates, and/or elevations. They are fixed points on which to spatially reference surveys, mapping, aerial and satellite imaging, etc

This layer uses event mapping to place all geodetic monuments maintained or owned by the Washington State Department of Transportation. The input table is exported daily at 2:00 AM from the production Survey Information System (SIS). Note if you need the coordinates for a station for survey work you should use the coordinates shown in the datasheet for the station NOT the coordinates contained in this layer for the feature.This service is maintained by the WSDOT GIS & Roadway Data Office. If you are having trouble viewing the service, please contact OnlineMapSupport@wsdot.wa.gov.

This map represents City of Salem, Oregon, Survey Benchmarks. The Survey Section of the Public Works Department establishes and maintains horizontal and vertical survey control throughout the City for most public and private projects. Vertical datum is NGVD 1929-47. Horizontal datum is NAD 1983-91. The map references detailed GIS data provided by the City of Salem Public Works Department. Contact the City of Salem City Surveyor (503-588-6211) for questions and the most up-to-date information, or gis@cityofsalem.net.

Survey Benchmarks