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lounsbury & associates, inc.
IRIS No. Z559670000
Final Project Report
September, 2015
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lounsbury & associates, inc.
Table of Contents
1. PROJECT OVERVIEW AND SUMMARY ................................................................................................ 1 2. SURVEY REDUCTION NARRATIVE ....................................................................................................... 1 3. HORIZONTAL AND VERTICAL CONTROL ............................................................................................. 1
3.1 Static Control Network Plot.......................................................................................................... 1 3.2 Static Control Verification – Free Network Adjustment Summary .............................................. 2 3.3 Static Control Verification – Loop Closures Report ...................................................................... 6 3.4 Static Control Verification - Baseline Processing Summary ......................................................... 8 3.5 Static Control Verification – Free Adjustment vs Record Control Values ................................... 10 3.6 Conventional Survey - Traverse Adjustment Reports ................................................................. 11 3.7 Conventional Survey – Traverse Adjustment vs Static Network Adjustment Values ................. 20
4.TOPOGRAPHY ...................................................................................................................................... 21 4.1 RTK Quality Summary Statistics ................................................................................................. 21 4.2 Topo Survey Checkshot Report ................................................................................................... 22
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1. Project Overview and Summary
Purpose of Survey:
The purpose of this survey was to establish a horizontal and vertical control network and to collect topographic data through the Chickaloon grade section of the North Glenn Highway (MP 77-79).
Date of Survey:
Fieldwork for this survey was completed by Lounsbury & Associates, Inc. during August 2015. The field crew consisted of Buku Saliz, PLS, Joshua Varney, LSIT, and Kirk Ayers.
Equipment and Methodology:
GPS surveys were performed using Topcon GR5 units. RTK control checks and initialization checks were performed regularly by re-shooting previously surveyed control points with different on-the-fly initializations. Topographic measurements were recorded in Tesla data collectors running Magnet Field v. 3.1 software.
2. Survey Reduction Narrative This project used the survey control plan sheets for proposed project AK DOT 135(2) , as provided by DOT&PF, as the basis of horizontal and vertical control. The following horizontal control statement has been adapted from the control statement on that drawing.
Coordinate System Summary
Coordinate System: This project is located entirely within the Matanuska-Susitna Valley MV-1 adjustment, a U.S. Survey Foot local surface grid coordinate system developed by the Alaska Department of Transportation.
Basis of Coordinates: The basis of Coordinates is NGS Station PURIN, located near Milepost 91 of the Glenn Highway. Said station has MV-1 coordinates of 231,730.0664 North, 232,079.1864 East.
Basis of Bearings: The basis of bearings is a local plane bearing between NGS Station PURIN and NGS Station PAQB. NGS Station PAQB bears S 64°53’54” W a distance of 189,974.66 U.S. Survey Feet from NGS Station PURIN. NGS Station PURIN has MV-1 coordinates of 151,137.6479 North, 60,046.5335 East.
Translation Parameters:
• To convert the local coordinates to NAD83 State Plane U.S. Survey Foot coordinates, translate using +2,624,893.3653 North, +1,738,991.4029 East, and scale using 0.999920217.
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Vertical Control Statement: The Basis of Vertical Control is NAVD88 as determined by a series of level loops performed by DOT.
Field Procedures
Horizontal control was collected using both Static GPS and conventional survey methods. Static control utilized Topcon GR5 receivers and the conventional survey methods used a Topcon ES-105L total station instrument. Static observations lasted a minimum of 20 minutes with at least 3 receivers running simultaneously.
Lounsbury’s horizontal control network included 18 recovered FHWA control points, 18 rebar and aluminum cap control points set for this survey, and 9 temporary control points set for this survey.
Vertical control utilized the provided elevations on the found control points and conventional traverse to transfer these elevations to set control.
The topographic survey was performed using Real Time Kinematic (RTK) techniques and conventional survey techniques. The conventional survey was performed using a Topcon ES-105L total station instrument with three dimensional backsight checks performed before and after each group of topo points collected from each setup. RTK measurements were acquired with Topcon GR-5 receivers. RTK control checks and initialization checks were performed regularly by re-shooting previously surveyed control points with different on-the-fly initializations. Topographic measurements were recorded in Tesla data collectors running Magnet Field v. 3.1 software.
Static Processing
Lounsbury & Associates used Topcon Magnet Software to process all static baselines and perform the GPS control verification. If necessary, individual baselines were viewed by timeline and manually cleaned to remove patchy satellite observable data or sections of excessive cycle slips on all recorded GNSS frequencies. Baseline processing was performed using the precise ephemeris and a default elevation mask of 15 degrees. After baseline processing, all possible combinations of 3-legged loops were investigated for errors in three-dimensional closure.
Initial post-processing of the recovered FHWA project control points yielded very good results and affirmed the integrity of the published values. These values were then held fixed in the final conventional and RTK processing efforts.
Processing - Conventional
Lounsbury & Associates used Carlson Software to process all conventional survey observations. After static processing was complete, the record values of all FHWA provided control was verified and these were used as the coordinate basis for conventional traverse. Each corner tied included a check angle set from a different backsight, and each computed coordinate was compared to its corresponding checkshot position. As a further check, static solutions were run on two set control points and compared to the conventional traverse adjustment, with good results. The conventional traverse adjustment report and the static checkshot report have been included in Sections 3.6 and 3.7 of this report document.
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Processing - Topography
RTK topographic survey data was processed using Topcon Magnet software. A large number of check shots were performed to ensure good on-the-fly initialization and to rule out systematic errors. The vast majority of RTK check shots were under 0.10’ magnitude in XYZ with a small percentage of outliers, all within the RTK precision specifications of the equipment used. Conventional backsight checks were typically under 0.05’ in magnitude utilizing final adjusted control values in post-processing. ASCII points were generated in Topcon Magnet software after reviewing the checkshot report and RTK system statistics reports. These reports have been included in the submitted deliverable package and are referenced in Section 5 of this report document.
The DTM was created in Civil 3D, reflecting existing ground and hard surface areas, using breaklines generated from the survey points as appropriate. The following DTM surface was created and carefully QCed:
CHICKALOON_EG
Problems Encountered
There were no significant problems encountered on this survey. However, there was construction encountered at the Chickaloon River bridge area. It should be also be noted that the FHWA set and found control points do not adhere to current DOT&PF point numbering standards, and that the provided FHWA control points only showed coordinate values to three decimal places. Finally, it should be noted that Civil 3D was the native software used for all topographic survey drafting and surface modeling. To assist with reconstructing the surface in GeoPak, the surface triangles have been converted to Microstation using the FHWA 3D seed file Sur_ft3D.dgn.
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3. Horizontal and Vertical Control 3.1 Static Control Network Plot
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3.2 Static Control Verification – Free Network Adjustment Summary
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3.3 Static Control Verification – Loop Closures Report
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3.4 Static Control Verification - Baseline Processing Summary
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3.5 Static Control Verification – Free Adjustment vs Record Control Values
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3.6 Conventional Survey - Traverse Adjustment Reports
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3.7 Conventional Survey – Traverse Adjustment vs Static Network Adjustment Values
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4.Topography
4.1 RTK Quality Summary Statistics
The following summary statistics were evaluated on the horizontal and vertical RMS of each RTK observation to ensure sufficient data integrity of the processed points. For the full RTK quality report detailing information for each vector, please see the deliverable directory.
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4.2 Topo Survey Checkshot Report
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