Civil Engineering Surveying

1. Civil Engineering Surveying Adapted from: Roy Frank

2. Planning A Survey • Planning requires a well rounded understanding of surveying practices • Process: • Choice of accuracy required (depends on use to be made) • Basic Control • Topographic • Photogrammetry

3. Planning A Survey • Existing Control • Search records for existing control in area • Illinois Geological Survey – Urbana, IL • National Geodetic Survey – Rolla, MO or Rockville, Maryland • Reconnaissance: • Search Procedure: • Description often dated • Can use GPS receiver (Lat. And Long) • Probe, detectors – often problems - brass

4. Planning A Survey • Choice of Instruments and Methods • Depends on availability, location, existing features, and accuracy • Computation and Drafting

5. Accuracy and Errors • Accuracy depends on: • Precise instruments • Precise Methods • Good Planning • Example: Angle turned with theodolite, pointed with care; readings checked thus good precision. Angle’s of 2-3” expected, real results angle’s 15” = accuracy

6. Errors • 3 Types • Blunders • Systematic Error • Accidental Error • Blunder is a mistake, to help eliminate: • Every value to be recorded must be checked by some independent field observation

7. Errors • Once check indicates that there is no blunder, field record must never be changed or destroyed • An overall check must be applied to every control survey. Make as many overall checks as possible.

8. Errors • Systematic Error – an error that under the same conditions will always be of same size and sign. • Basic Rules to Eliminate: • All surveying equipment must be designed and used so that whenever possible systematic errors will be eliminated automatically • Systematic error which can not be eliminated must be evaluated and their relationship to conditions that cause them must be determined. • Example: Temperature Corrections

9. Errors • Accidental Errors – (random errors) represent the limit of precision in the determination of a value • Corrected be laws of probability • Compass Rule and Least Squares

10. Hydrographic Surveys • Surveys and mapping of bodies of water and shorelines • Rivers and Lakes – Process different • Rivers • Normal process is to establish 2 parallel lines of control points on opposite sides • River Portion: 2 processes • EDM similar to radial • Dual instrument with position by angle and intersection • Lakes • Normal process same as river but generally do not have current problems

11. Overall Process: • Establish control points both horizontal and vertical • Preplan where sections are to be taken (this is basis for control points on shore) • Cross sections taken • If EDM, radials taken from control points due to difficulty in obtaining shots under 300’ • May have to combine cross sections and radial location to pick up anomalies not covered by cross sections

12. Gauging Stations • Purpose is to install either manually read or automatic gauges to determine stream, river, lake, or ocean elevations • Process: • Establish system of BM’s throughout area gauges will be installed • Establish elevation mark at site for installation • After gauges are installed, check elevation of each

13. Topographic Surveys • 6 Basic Methods • Radial • Plus/Offset • Plus Offset • Establish baseline (Often centerline), establish points at station interval 50’, 100’, 200’ • Tie planimetric data by distance down line plus distance right or left (looking up stationing) • Establish elevations on station points then elevation out a predetermined distance with shots at breaks

14. Topographic Surveys • Due additional section to locate features in between stations • Equipment: Tape, Level, Rod, Transit, - Right Angle Prism? • Grid Method • Take cross Section Groups and Combine • Establish Grid baseline – often property line • Establish Perpendicular line • Both Marked at grid interval (25’, 50’) • Planimetric tied plus/offset in each grid • Grid laid out by double taping • Field notes 1 – 2 grids/page

15. Topographic Surveys • Photogrammetry • Limitations • Trees – Leaves off – no large growths of coniferous • Ground Cover – grass, thick weeds and vines, snow • Clear Sky • Tall Buildings • Due to these Limitations Illinois only has on the average of 2 weeks flying time

16. Topographic Surveys • Scale – Photo • S = (f/H’) • Coordinates From Photos • XA = (xa/f)(H-ha) • YA = (ya/f)(H-ha) • Height of an object • r = radial dist. to top • d = radial dist. to top – radial dist. to bottom • h= d (H’) / r

17. Topographic Surveys • GPS: Total Station System • Basic of GPS • Topo with GPS • Topo: Trimble Total Station (RTK) • Limitations: • Must be able to maintain satellite signal – Trees, Building • Signal Reflection (Multipath) – Buildings, Fences, Roofs • Debate over elevation (0.15’ +/- my belief)

18. Topographic Surveys • Trace Contour • Used to identify several contours around an area • Plane Table Surveys • Rarely used • Method prepares a manuscript map in the field

19. Mapping and Map Drafting • 2 Basic Types of Maps used in Engineering • Line Drawing • Photogrametrically prepared manuscript or orthophoto map

20. Mapping and Map Drafting • Datum in Mapping: • Datum used to correlate measurements, to determine elevations and horizontal positions for points at different locations • Topographic Maps using Symbols Show: • Spatial configuration of Earths surface (contours) • Natural Features (Lakes, Rivers, etc.) • Physical Changes caused by man

21. Mapping and Map Drafting • Planning Maps • Used in planning Engineering work or overall planning at the urban, Regional, or National Levels • Plotting Contours: • Interpolation: • Estimation • Computation

22. Mapping and Map Drafting • Contours • Characteristics of Contours: • Horizontal distance between contour lines is inversely proportionate to the slope • Uniform slopes have contours evenly spaced • Along plane surfaces (manmade) contour lines are straight and parallel • Contour lines are perpendicular to lines of steepest slope • All contours close upon themselves • Different contours do not merge or cross one another (except vertical walls, overhangs, cliffs) on map

23. Mapping and Map Drafting • Factors that influence choice of map scale • Clarity with which features can be shown • Cost (larger scale – higher cost) • Correlation of Map data with related maps • Desired size of map sheet • Physical factors (number and character), nature of terrain, required contour interval

24. Mapping and Map Drafting • Map Classifications • Based on American Society of Civil Engineering, Surveying, and Mapping Division • Design Maps: • Used to design and construct • Information shown on Maps:

25. Mapping and Map Drafting • The following should be on a map: • Direction of Meridian (North) • Graphical Scale (Bar in case of reduction) • Legend or key of symbols • Title Block (identifiers) • Contour Interval • Datum to which both Horizontal and Vertical are Referenced • If coordinate base used – what system

26. Mapping and Map Drafting • If map is to become public record (subdivision). It must contain in addition to the above: • Length of each line • Direction of each line (bearing or angles) • Subdivision numbering system (lot and block) • Location and Kind of monuments • Names of property owners (on site and adjacent) • Full description of Boundary • Certificate of Surveyor that map is correct

27. Planning and Estimating from Topo Maps • Purpose of Topo maps • Profiles • Grade contour • Drainage Area • Limits determined by following characteristics: • Begins and ends at the point in the stream to which it applies • Passes through every saddle that divides drainage area • Often follows ridges • Reservoir Capacity

28. Earthwork Computations by Average End Area Prepare Cross Sections Differentiate between existing & proposed Planimeter Cross Sections Amount of cut & fill for each cross section Beginning and end stations have 0 value Compute Volume Conversion Constant: 1.852 = (100/27)/ 2 = {(Sta. Dist.)/ [CF/CY]} / 2

29. Earthwork by Average End Area • EARTHWORK BY AVERAGE END AREA (EXAMPLE) • END AREAS: STATION CUT EMBANKMENT 0+00 0 0 1+00 10 156 2+60 50 795 3+00 197 1526 4+80 5 110 5+00 0 0

30. SAMPLE END AREA STATION SUM SUM CUT FILL CUT FILL D/100 CUT FILL CUT FILL 0+00 0 0 10 156 1.0 10 156 10 156 1+00 10 156 60 951 1.6 96 1522 106 1678 2+60 50 795 247 2321 0.4 99 929 205 2607 3+00 197 1526 202 1636 1.8 364 2945 569 5552 4+80 5 110 5 110 0.2 1 22 570 5574 CUT: 570 X 1.852 = 1056 Cubic Yards EMBANKMENT: 5574 X 1.852 = 10324 Cubic Yards Compaction Factor = 25%, 10324 CY X 1.25 = 12905 CY Fill

31. U.S. Rectangular System • “IDEAL” Process: • Area divided by establishment of Principal Meridians and Baselines • Area divided into 24 mile square tracts quadrangle using guide meridians and Standards of Parallel (correction lines) • Divide 24 mile² tracts into 16 townships each 6 miles square • Divide townships into 36 one mile square sections

33. U.S. Rectangular System • “IDEAL” Process: • Area divided by establishment of Principal Meridians and Baselines • Area divided into 24 mile square tracts quadrangle using guide meridians and Standards of Parallel (correction lines) • Divide 24 mile² tracts into 16 townships each 6 miles square • Divide townships into 36 one mile square sections

34. Easements • Easement is a Legal document which allows someone to do something to and or through your property • Types: • Access (ingress/egress) • Construction • Water rights • Utility

35. Easement must Describe • What it is for (purpose) • Who between Must be signed by all who’s name appears on deed • Width of easement • Duration – specified number of years or perpetual or life • Description of where located Based on Rectangular system unless subdivision

36. Description Method for Waterline Easements • A strip 30 feet wide over, under, and across the _____ side of the _____ ¼ of the _____¼ of Section, ___, T__ __, R__ __of the ___ P.M., __________ County, Illinois said strip lying ______ of and adjacent to the _______ right of way line of the existing public road.

37. Global Positioning System(GPS) • Worldwide system of navigation satellites by U.S. Department of Defense • Started in 1982 • Civil GPS Service (CGS) • Views civil users in 3 groups: • Professional • Commercial • Recreational

38. Global Positioning System(GPS) • Provides info in 4 categories: • Planning information • Current status information • Historical information • Responses to user questions

39. Global Positioning System(GPS) • Information may be obtained from: • DOT/RSPA ATTN DMA 26 Room 8405 Washington, DC 20590 • Commandant USCG Headquarters G-NRN-2 2100 2nd Street SW Washington, DC 20593

40. Global Positioning System(GPS) • Information may be obtained from: • National Geodetic Survey NOAA; N/CG 142 Rockwall 306 Rockville, Maryland 20852

41. Global Positioning System(GPS) • Satellites broadcast on 2 bands • L1 modulated with P code (Precise Positioning Service – PPS) • L2 modulated with C/A code (Standard Positioning Service – SPS) • C/A mode intended for general use and capable of providing single point positioning • P mode is much more accurate but is reserved for military and government use

42. Global Positioning System(GPS) • Planning GPS Surveys – as important as the sophisticated needed to collect the data • Planning Phases: Presurvey reconnaissance; 2 stations site requirements; 3 connections to existing geodetic control; 4 network design; 5 satellite availability; 6 observing schedule

43. Global Positioning System(GPS) • Reconnaissance (presurvey) • Important to minimize delays or changes in observing schedule • Office planning • Obtain station descriptions • Prepare control diagrams • Preliminary Reconnaissance • Determine recoverability of existing control stations • Provide sketch showing existing and proposed stations • Suitability of existing stations for use by GPS

44. Global Positioning System(GPS) • Station site Selection (critical factors) • Obstructions with elevations greater than 15º-20º above horizontal should be avoided • Station mark must be suitable for occupation by tripod

45. Global Positioning System(GPS) • Networks Design • Design depends on • Surveys order and purpose • Number of receivers available • Desired spacing between stations • It is best to connect at least 3 existing geodetic control stations

46. Global Positioning System(GPS) • Field Operations • Survey team structure – determined totally by operation method • Numbers depends on: • Number of receivers • Number and length of observation stations • Time spent transporting equipment • Logistics and administrative needs

47. Global Positioning System(GPS) • Transportation • Monumentation • Power supply • Weather

48. Global Positioning System(GPS) • Total Process: • Establish receivers and have all track simultaneously • Data cleaned – search for ambiguities in data to identify correct integer values • All vector solutions are computed • 2-3 are accomplished by built in receiver computer • Data given by longitude and latitude

49. New System: NAVSTAR • L2C – civil signal – added to L2 with P code • Block II RM Satellites – Launch 2005-2009 • L5 – New Frequency – more powerful and larger bandwidth • Provides easier signal acquisition and tracking • Block IIF Satellites • Functional in mid 2013

50. GPS Field Data Collection Techniques • Static – minimum 3 receivers • Occupation/session 1-3 hours • PDOP < 6 with 4 satellites • Occupy 3 stations then move 2, leap frog techniques • Pseudo Static – can work with 2 receivers • Occupy for 2-5 minutes, each station must be occupied twice approximately 2 hours apart • Can loose satellite lock for short periods • PDOP < 5 with 4 satellites