![]() ![]() Often you come across question like “are you a person with benchmark disability?”. Therefore, all City of Eugene benchmarks within the City of Eugene Urban Growth Boundary with a NAVD 88 elevation have been established by adding an adjustment factor of +3.87 feet in elevation from the previous established elevation being an NGVD 29 based elevation.Government of India uses the term benchmark disability quite often in the official communications regarding persons with disabilities. In the analysis of the common benchmarks between the City of Eugene and the National Geodetic Survey database the actual difference is 3.87’. Using the National Geodetic Survey computer program "Vertcon" the calculated difference between NGVD 29 and NAVD 88 is 3.61’. All ten of the benchmarks used in the analysis where also within the National Geodetic Survey database. Ten benchmarks located within the Urban Growth Boundary of Eugene were used in the adjustment study. In 2012 the City of Eugene calculated the vertical adjustment to create elevations for their benchmark on the NAVD 88 vertical datum. However, these elevations are not considered to be "First Order", as all procedures for First Order levels were not followed in all loops. It was found that, by carefully following a set procedure and keeping shots within 150 feet, this accuracy was generally attainable. The goal was first order accuracy of Â☐.02 vM, where M is the miles in the circuit. Also, note that in some parts of town (near west side, Bethel Danebo) expansive soils exist and can produce annual variations in Bench Marks up to 0.10 feet.Ī Leica NA2002 digital level was used for these new level circuits. A few elevation errors were found on existing bench marks (not all bench marks were reshot) from the 1974 publication, these elevations have been revised to reflect the new elevations. ![]() With the 2001 update, most bench marks set on fire hydrants, power poles and scribed marks on structures within private property have been removed. ![]() Monuments set in the 2001 update are 3" brass caps stamped: The second control bench is X94 (USC & GS) at Eugene, on the Southern Pacific Company Railroad Station Building at the north end of 5th Avenue, in the center of the curved wall (north side of building) facing the track, about 3.5 feet above the pavement stamped "X94 1931" Elevation 430.993. The first control bench is "449 (USGS)" at Eugene, on the Campus of the University of Oregon, on the northeast corner of Villard Hall, in the North face of the building, 2 inches below the date "1885" and stamped "449B1903" Elevation 449.320. Two base bench marks were used for the City Datum. As time passes and additional Bench Marks are needed, the City will add to this network and addendums will be issued.Īll elevations are on the 1929 National Geodetic Vertical Datum (NGVD 1929 Datum). For these reasons, the City decided to update the vertical control network during the summer of 2001. Many of the original bench marks were destroyed and, as the City of Eugene grew, very little vertical control was established in much of the outlying areas. ![]() Over the course of time, the City’s Bench Mark system has become outdated. The City’s last update to the Bench System was in June of 1974. The City of Eugene Code Chapter 7.087 (2) states the City Engineer shall place bench marks on all lines run with a level for establishing streets, grades, levels, sewers and drains. Link to Benchmarks Map Application Use the interactive map application to research survey elevations. ![]()
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