PSLS Reaching New Heights to Continue
National Surveyors Week is over, but PSLS continues its ambitious campaign known as Reaching New Heights, which will reap benefits for surveyors, the public, and anyone using geospatial data with a vertical component for years to come.
In an effort to improve the geoid and implement the next iteration of our vertical datum, PSLS is seeking volunteers to occupy First and Second Order Bench Marks with dual-frequency GPS receivers for 4.5 hours. This data will be submitted to OPUS and the solutions published so NGS can use them to refine the current geoid and to develop the upcoming vertical datum known as GRAV-D. PSLS is working to make the process as simple as possible to accommodate those familiar with OPUS and those that are not. If you are unfamiliar with GPS but want to help there is a need to recover bench marks even if they aren’t going to be occupied during Surveyor’s Week.
Watch the recorded webinar
given on February 18, 2015 which discusses this effort.
Benefit to Surveyors:
While the accuracy of the geoid model in Pennsylvania has improved with each new iteration, there are still many large areas in the state where the accuracy is poor as noted by the red areas shown on the interactive map
The National Geodetic Survey (NGS) has undertaken what it considers one of its most ambitious projects in history known as Gravity for the Redefinition of the American Vertical Datum (GRAV-D). The goal of this project is to develop a new vertical datum accurate to 2cm which will be accessed through GPS derived ellipsoid heights and applying the GRAV-D geoid model. This means accurate elevations are going to depend on an accurate geoid model and NGS needs our help to make this happen!
We must greatly increase the number of bench marks with GPS derived ellipsoid heights on them. By strategically identifying First and Second Order benchmarks to occupy and submit to OPUS-DB, we have the opportunity to improve future geoid models and the implementation of our next national vertical datum.
Details on volunteering can be found in the Volunteer Handbook which should be reviewed in detail and contains Frequently Asked Questions as well as some notes on safety and access. The process can be summarized as follows
Volunteer for a point grouping
Use the interactive map
to find a point grouping convenient for you. Review the aerial imagery and NGS Datasheets. When you have found a point grouping you want to volunteer for, click on any point in the group and click on the Volunteer link and complete the volunteer form
Recover the point grouping
At least one week prior to the planned occupation day recover the points in your point grouping and determine which one is the most suitable for GPS occupation. Take a close up and legible digital photograph of the mark. Standing over the mark take digital photographs facing North, East, South, and West so the horizon is visible in the lower portion of the photograph. Also standing over the mark take digital photographs of any obstructions not well documented in the N, E, S, W photos. Optionally, you can take a video while standing over the mark and turning 360 degrees.
Submit Point Recovery
Once you have decided on the point most suitable for GPS occupation, submit your recovery information for that point using the recovery form
. You can also use the interactive map
to click on the point you will occupy and click the Submit Recovery link.
Occupy the point
During National Surveyors Week occupy the point for 4.5 hours using a dual-frequency GPS receiver. We highly recommend you use fixed-height tripods or a fixed-height rover rod with a bipod. It is also recommended that you use sandbags to stabilize the tripod/bipod. Two more digital photographs are needed. One showing the antenna model sticker on your antenna and one picture with the GPS receiver occupying the mark level with the horizon along with any identifying features in the foreground or background. During the occupation it is helpful to document your occupation using some of the forms provided by NGS
specifically the OPUS Field Log
I am familiar with OPUS:
One or two days after your occupation, submit your data to OPUS. When you have the result please submit the OPUS report and other required information and photographs to PSLS using the occupation form
which can also be accessed by clicking on the occupied point on the interactive map
and clicking the submit occupation link. We will review the data and let you know if the solution should be shared.
We ask that you include PSLS Reaching New Heights 2015 in your description.
I am not familiar with OPUS:
Submit your raw GPS data, digital photographs, and other information to PSLS using the occupation form
or by clicking on the occupied point on the interactive map
and clicking the submit occupation link. We will process and review your data and share the solution using OPUS-DB being sure to cite you as a contributor.
That is it! We hope you can help us out.
Regional Coordinator Handbook
Regional Coordinators – Visit the interactive map
to find your regional coordinator and their contact information
Regional Coordinator Manager:
Adam Crews, A.Crews@CrewsSurveying.com
Brian Naberezny, email@example.com
Public Relations Managers:
Brian Buzard, firstname.lastname@example.org
Mike Kreiger, email@example.com
Frequently Asked Questions:
1. What if I don’t find any suitable marks in my point group?
Contact your Regional Coordinator or the Technical Manager. They will try to assist you by finding alternate points or another point grouping.
2. What if I know a better mark close by?
Verify it is a First or Second Order mark by consulting the NGS Datasheet. If it is, contact your Regional Coordinator or the Technical Manager. If it is within 1-2 miles it will most likely work out fine. If it is more than 2 miles away it may not be suitable for our purposes. Either way check with your Regional Coordinator or the Technical Manager.
3. What if my organization wants to occupy multiple points?
Great! Either submit the volunteer form for each point group or contact your Regional Coordinator or the Technical Manager to coordinate with them.
4. What if I want to volunteer but can’t make it happen during Surveyors Week.
Not a problem. Anytime in March is acceptable. If you can’t perform the work until April, let us know when you plan to occupy the point in the notes section of the Volunteer form and we will do our best to accommodate.
5. What if I am not familiar with GPS but I want to help?
There is a large need to recover bench marks. You can find someone in your area to team up with on your own or through the help of your Regional Coordinator. You can recover the mark(s) and the other volunteer can perform the occupation(s). If you don’t have someone to team up with contact your Regional Coordinator or the Technical Manager to find out which bench mark recoveries would be the most beneficial.
1. PSLS has not performed any research into ownership of the property on which the marks are located. Please seek land owner permission for recovering or occupying any marks located on private property.
2. Many marks are located along rail road tracks. PSLS has not made any attempts to determine which lines are active, inactive, or abandoned. Always exercise caution when working around rail road tracks and remain in compliance with any rail road policies regarding access and safety.
3. Many marks are located adjacent to roads or on bridges. Always exercise caution when working in, on, or near roads or bridges being sure to deploy any necessary traffic signage or cones.