Central Valley Control Network - Epoch Date 20120914 Coordinates Published

[Sunburned_Surveyor]

As part of the work locating centerline monuments in San Joaquin County that is currently taking place, I needed to establish a control network. The control network is going to be used to derive state plane coordinates for the located centerline monuments.

San Joaquin County doesn't have a good up-to-date horizontal or vertical control network.

I've used static data from CORS, PBO Stations, and the CSDS RTN to create a network that covers all of San Joaquin County and portions of surrounding counties. The network was created by processing 3 days of static GPS data from the first three (3) days of 2012. The static data from each 24 hour period was processed and adjusted independently using the final published GPS orbits. The published horizontal coordinates for all CORS were held in each network adjustment. The NAVD 88 elevation of CORS S300 was held in each network adjustment. The derived coordinates from each day were then compared, and accuracies at the 95% level were calculated.

This process resulted in the establishment of NAD 83 horizontal coordinates and NAVD 88 vertical coordinates on the latest NGS datum for all of the PBO stations and the CSDS RTN stations in the network. I'm publishing the final coordinates from this process in a spreadsheet today, as the Central Valley Control Network, Epoch Date 2012-09-14.

This version of the control network will be used to calculate the centerline monument coordinates from this summer's chip seal projects. It will also be used to calculate the secondary control point coordinates for control monuments we've been setting during the chip seal project.

You can view all of the data for this release of the Central Valley Control Network here:
http://www.mediafire.com/?bh2d891c77m66

This includes all of the static GPS data, the GNSS loop closure reports, the minimum and full network adjustment reports, the Trimble Business Center project files, the analysis of the coordinate accuracy, a spreadsheet with the final coordinate values, and a CSV file with the final coordinate values.

I'll work on the producing and releasing the following items before the end of the year:

1) A 24" X 36" map set showing the control network (both primary and secondary control points) on some reference GIS data.
2) Datasheets (including photos) for all of the secondary control monuments.
3) GIS files for the control network.
4) A detailed survey control report for the work done this late summer and fall.

My goal is to release regular updates to the network as:
1) NGS makes changes to the local CORS network or CORS horizontal and vertical datum.
2) I'm able to validate and strengthen the network with KSN or contributed static GPS observations.
3) Secondary control points are added by KSN or other contributors to the network.

I'm in the process of developing some classifications for the control points based on their expected stablility and the calculated accuracies.

Please let me know if you check into parts of the network with RTK GPS, RTN GPS, Static GPS, traverse ties, or leveling runs. I'd really like to use this data to verify and strengthen the network. I'm very grateful for any contributions.

I also want to thank KSN for donating the equipment, truck, software, hardware, and other resources to make this possible.

Remember I'm no geodisist. Don't beat me up too much when you look at the data. If there is something I need to fix or correct, let me know. This is the first time I've done something on this scale and made it public. I'm sure there are things that can be improved.

If you want to reference the control network on a survey document, please use the following citation:

Central Valley Control Network, CLSA Central Valley Chapter, San Joaquin County Government Liaison Committee (Epoch Date 2012-09-14)

I'll post updates about the network here. I hope the data will be useful in the work of other Central Valley surveyors.

Landon

P.S. - I'm very pleased with the accuracies of the network at the 95% confidence level. Quite a few of the points are a less than 0.02 feet horizontally and vertically at that level, and most are under 0.05 feet.

[land butcher]

Where are the pictures :)