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September 23, 1998 |
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September 23, 1998 I am pleased to inform you that the survey control project anticipated last October has been completed. Attached to this letter is the following:
Volunteers: Many firms and agencies volunteered assistance in locating and setting monuments on this control project. We at Johnson County want to thank those firms and agencies that volunteered there assistance in this project. We estimated that over $50,000 of work has been donated by the survey community. To those firms and agencies that assisted us with the project we are sending a full set of reference sheets for both the horizontal and vertical control. Cooperating firms and agencies were: Allenbrand-Drews, Anson & Associates, Bartlett & West, Bucher Willis & Ratliff, Campbell Barber & Lambeth, Cook Flatt & Strobel, Jimmy DeMasters, George Butler, Green Engineering, HNTB, Kaw Valley Engineering, KCPL, KDOT, Larkin & Associates, LHE, MJ Harden, Payne & Brockway, Phelps Engineering, Schlagel & Schmidt, Schmidtz-King, Shafer Kline & Warren, TransSystems, and Ubben Surveying, public works departments for the cities of Gardner, Leawood, Lenexa, Mission, Olathe, Overland Park, Prairie Village & Shawnee. I also want to thank Murray Rhodes, Wyandotte County Surveyor, Stephen J. Frakes, NGS, Monroe Rivers, NGS, and J. Michael Flowers, Missouri State Surveyor for technical assistance and advice. Vertical Control: The vertical control network consists of a 125-mile series of level loops tying into NGS first order benchmarks. The benchmarks are shown on the attached index map. You should note that some monuments are both bench marks and GPS horizontal control monuments. All existing NGS first order benchmarks in the county were located. These first order benchmarks were mainly located along Shawnee Mission Parkway, K-10 Highway, and K-7 Highway north of Olathe. Second order or better level loops were performed using a digital level and bar code level rods. The closure of the level loops is shown with the data. The elevation of the HARN monument ZKCB was used as the base elevation. All elevations are NAVD88. Our level loops which started at ZKCB matched the 1st order NGS elevations along Shawnee Mission Parkway, K-10 and K-7 within 0.04 ft. It was not considered appropriate to hold elevations of existing benchmarks and require major office adjustments in the level loops so elevations shown on the attached sheet do not exactly match NGS published elevation. More benchmarks will be established along major stream channels as part of the stormwater mapping studies. Hopefully, there will be a benchmark near every major stream crossing in the county within four years. Horizontal Control: The horizontal control network consist of 69 stations at locations shown on the attached map. No azimuth marks were set, so these monuments are only intended for use with GPS surveying. The City of Overland Park and the Johnson County Public Works base stations were also included. We were fortunate to have an A-order HARN station near the center of the county. HARN coordinates became available from NGS in January, 1998, so coordinates of the horizontal control network will be NAD 83 (1997). Since some of our GPS horizontal control monuments were also benchmarks on the control level loops we have very good control to obtain GPS derived elevations for the remainder of the GPS monuments. We feel that all GPS monuments have elevations within 0.1 ft. NAVD88. This vertical accuracy makes our GPS network unique and much more useful for mapping purposes. Web Page:
Our web page is now operational at www.jocogov.org/pubwrks
. Current information is available on both the horizontal and vertical control. It is basically in lists rather than on a map. You will need an index map handy in order to speed up the process.
The index map is enclosed with this letter, additional copies may be purchased for $10 from our mapping department. Monument Maintenance: One item that became apparent as we were searching for
existing monuments, is how easy it is to destroy a monument. Half of the AIMS monuments set in 1986 have been destroyed. We need everyone's help to maintain our survey network. We ask that you become
familiar with the location of monuments in your area. Please notify us if a sign is down or there is construction activity around a monument. When performing a site survey please be sure to point out any
control monuments in the area, and tell the owner or architect the importance of saving the monument. Any site plan you prepare with a benchmark in the vicinity should include a note not to damage the
monument. Future Items: There are a number of unfinished items that will need to be addressed. A main goal at Public Works is to have section corners on state plane
coordinates. We need to address accuracy requirements, monuments, and methods. We also need to decide when state plane coordinates will be required on new plats. Education on GPS procedures and state
plane coordinates will be a major task that needs to be addressed prior to any requirements to use coordinates on subdivision plats. We are also working on specifications to be included in engineering and
construction projects concerning ties into the control network as well as preserving existing monuments. Closure: Again, thank you to all who volunteered their help and assistance on this
project. Due to this help we have one of the finest vertical control and GPS horizontal control network in the country. Please share information on our control network with all surveyors and designers in
your firm. We need as many people as possible to know about our control network, both to utilize it as much as possible and to help avoid damage to the monuments May 22, 1998 HARN adjusted coordinates were available for ZKCB, so coordinates of the horizontal control network
will match HARN. New coordinates will be determined for existing monuments, including those NGS non-HARN stations. Five the Lenexa monuments will be used, but adjustments of previous values are expected. The data from
the EPA base station was not accessible and was not used in network control. Some of the monuments were in the level loops, and so will have elevations within a few millimeters. It appears from the observations that the
remainder of the monuments will have GPS derived elevations plus or minus 2 centimeters. Vertical Control Monumentation: Vertical control network will consist of a 125-mile series of level loops
tying into NGS first order benchmarks. Our HARN monument ZKCB located near the college in Olathe was used as the datum benchmark. About 3/4ths of the level work has been completed. The level loop is expected to be
completed in mid-June. Using the digital levels, the first level loop of 48 miles closed within 0.13 ft. All existing NGS first order benchmarks in the county have been located. We find we are matching these NGS
benchmarks within 0.03 ft. As you probably know, many of the old benchmarks do not match each other very well, this includes NGS second order benchmarks. We anticipate publishing new elevations for the existing
benchmarks on the level loops, and ignore the old published elevations. We recommend that for major projects that surveyors do not rely on anything but NGS first order bench marks, or benchmarks in the control level
loop. Web Page: A web page is under development for access to survey data. Data will include horizontal and vertical control established as part of this project. Section corners will also be included as coordinates
are established. We are also working on an index for section corner reference reports, which will also be available on the web page. We anticipate that the web page will be available for use in late July. Future
Items: There are a number of unfinished items that will need to be addressed. A main goal at Public Works is to have section corners on state plane coordinates. We need to address accuracy requirements, monuments, and
methods. We also need to decide where state plane coordinates will be required on new plats. Education on GPS procedures and state plane coordinates will be a major task that needs to be addressed prior to any
requirements to use coordinates on subdivision plats. We plan on having a GPS survey class later in 1998. If anyone knows of some good speakers or instructors for this course please call me or Wayne Malnicoff.
Norm Bowers GPS observation of these points will occur later in the spring. HARN adjusted coordinates have been received for the EPA base station and
ZKCB, so coordinates of the horizontal control network will match HARN. New coordinates will be determined for existing monuments, including those NGS non-HARN stations. Five the Lenexa monuments will be used, but
adjustments of previous values are expected. M J Harden has been hired to do the GPS observations and adjustments. We expect to have data available by the end of April. Vertical Control Monumentation:
Vertical control network will consist of a 125-mile series of level loops tying into NGS first order benchmarks. The new bench marks along the 125 mile level loop have been set by private survey companies that volunteered to participate in this project. Private survey companies were assigned approximately 10 miles of the bench loop. They set one or two benchmarks per mile, and referenced existing benchmarks on the loop. The new benchmarks consist of 2" dia. aluminum domed caps set in existing stable concrete structures such as bridge and box culvert headwalls. New monument record sheets were completed for each benchmark. The following companies participated in setting and referencing new and existing benchmarks. Bucher & Willis, HNTB, George Butler, Schlagel & Schmidt, Cook, Flat & Strobel, Jimmy DeMasters, Ubben Surveying, TransSystems, and LHE.
All existing NGS first order benchmarks in the county have been located. The first order benchmarks were mainly along Shawnee Mission Parkway and K-10 Highway and two in Olathe. Nearly all the first order benchmarks
along the interstates have been destroyed by construction projects. Second order level loops will be run in the spring, the leveling work will be done with digital levels. Shafer, Kline & Warren is currently running
about 35 miles in the north half of the county. These level loops will essentially bring elevations south from Shawnee Mission Parkway and tie between most of the existing 1st order NGS benchmarks. As you probably know,
many of the old benchmarks do not match each other very well. We anticipate adjusting the elevations of prior existing benchmarks that do not match the 1st order NGS benchmarks. It was not considered appropriate to hold
elevations of existing benchmarks and require major office adjustments in the level loops. Web Page:
A web page is under development for access to survey data. Data will include horizontal and vertical control established as part of this project. Section corners will also be included as coordinates are established. We are also working on an index for section corner reference reports, which will also be available on the web page. We anticipate that the web page will be available for use in late April. Currently we are posting monthly updates on the survey control project on the web page, we invite you to check on the status of the project at
Monument Maintenance:
One thing that became apparent as we were searching for existing monuments, is how easy it is to destroy a monument. Half of the AIMS monuments set in 1986 have been destroyed. We need everyone's help to maintain our survey system. We ask that you become familiar with the location of monuments in your area. Please notify us if a sign is down or there is construction activity around a monument. When performing a site survey be sure to point out any control monuments in the area, and tell the owner or architect the importance of saving the monument. Any site plan you prepare with a benchmark in the vicinity should include a note not to damage the monument.
Stormwater Study:
This survey control project is being funded as part of the update of aerial mapping for AIMS and a stormwater study. Aerial photo flights are scheduled for Mill Creek and Blue River basins this spring. Sufficient control must be in place in these basins in time to panel for aerial photos. We at Public Works commend John Kahl and Derrek Sherry who recognized the need and understand the importance of establishing a permanent survey monumentation network to build accurate maps and to provide updates that match previous work. We in the survey community will use the control network for other purposes and it is our feeling that the investment in survey control will have a large payback.
Future Items:
There are a number of unfinished items that will need to be addressed. A main goal at Public Works is to have section corners on state plane coordinates. We need to address accuracy requirements, monuments, and methods. We also need to decide where state plane coordinates will be required on new plats. Education on GPS procedures and state plane coordinates will be a major task that needs to be addressed prior to any requirements to use coordinates on subdivision plats. Over 30 private survey firms have volunteered to assist on this project. We at Johnson County want to thank those firms that volunteered there assistance in this project. We estimated that over $50,000 of work has been donated by the survey community.
Posted: January 23, 1998 Volunteers: Over 30
private survey firms have volunteered to assist on this project. These volunteers will physically set horizontal and vertical control points. To volunteer or to be included on the GPS mailing list, just call or leave
a message with Jackie at 782-9379 ext. 306. Posted: November 26, 1997 Currently:
Committees will be formed to determine potential sites, evaluate sites and finally, recommend sites. Schedule: Aerial photo flights are scheduled for as early as
March 1998. Sufficient control must be in place in time to panel for aerial photos. |
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