Surveying Final
Points
Points are described by x, y coordinates in vector mode, Points are described by a grid cell in raster mode, Examples: electric pole, fire hydrant etc
Profiles derived from a contour
Profiles are ground elevations along a given line/route, Profiles can be prepared by surveying as we did in leveling or can be calculated through topographic map, To draw a profile from a topographical/contour map, Set a starting point on the map. Set a line through which profile is required. Measure distance to each contour line from the origin, and convert that to ground scale by multiplying it with scale factor. Make profile with available chainage and elevation
Spiral Curve Insertion
R or are given by design requirements (usually speed) Stationing of PI is determined in the field Δ is determined in the field LS is chosen with respect to design speed and the number of traffic lanes see page 226 for formula
Computerized survey computations and drawing preparation
Sometimes survey data are transferred directly with X, Y, and Z coordinates. However, sometimes, digitized data (in the form of lines, polygons and points) are transferred to the computer directly, Various software have capability to close and adjust traverse, Graphic labels can be automatically prepared using feature coding, Based on the X, Y, and Z data, computer program prepares the digital elevation model (DEM) or digital terrain model (DTM) directly. DEM and DTM are synonymous, except, DTM has break lines that show the break in slopes. Based on the DEM, the program directly draws contour lines, Some of the programs compute earthwork quantities, whereas the other programs plot the designed road levels, horizontal curves, and coordinates of designed features, Recently, various software are available to plot the change in topography after the completion of any construction works.
Geocoding
Sometimes, similar features and database can be transformed into a new system based on the type of data using "Geocoding" function of the software, One of the "attribute table" column is identified and linked to the available spatial data for this feature.
Sewer Plan and Profile
Stakes should not obstruct the movement of the construction machines. 0+00 starts from the manhole and offset distance is about 15 ft. Center line of the sewer line is first staked out as follows, Set a stake at manhole (MH) 1 and sight at MH2. As the distance between MH1 and MH2 is known, drive the stake at the center of MH2. Turn the total station at 900 and measure an offset distance of 10 to 15 ft (this should be consistent). Set up the total station at MH2 stake, sight at MH1 stake and set up MH2 offset stake at the same side and distance as in the MH1. Consider the stake at MH1 as 0+00, set up stakes at the center of the invert line at 20 ft. interval, either using the Total Station or the steel tape. Transfer the offset stakes at the same side and at the same offset distance as in MH1 and MH2. Note the elevation of the center line at those offset grade stakes. Based on the invert level of the first station (MH1) and the gradient of the sewer line, calculate the invert level for those stations. Calculate cutting and filling depths at each station base on the elevation of offset stake. (Don‟t be confused with the elevation of the stake. It is the elevation of the center line not the exact elevation of stake itself). Set batter board at about 1 ft. away from the offset grade stake, keep the cross-pieces horizontal. Nail on the batter board at the center line of the invert level. The elevation of the nail at the first station should be at even ft. height based on the eye height. The position of nail at the other stations should follow the slope of the invert level. The elevation of the stake always represents the elevation of the center line. From the top of the batter board, always even foot measurements are taken for the first stake, and elevation of the batter board is set in that way. Elevation of the batter board (nail) is set at the grade of the invert level. However, free standing batter boards are common lately. Top of the first batter board should be at the comfortable eye height.
Vertical Curve Geometry
Vertical axis parabola (figure 9) is used for the vertical curve because it provides, Constant rate of change of slope Easiness in computation of offsets see page 222 for diagram
Reverse Curves
When the direction or convexity of one curve is opposite to the other interconnected curve (figure 7), it is called reverse curve. They are used to change the direction smoothly. see page 221 for diagram
Super elevation
While designing a pavement in horizontal curves, the road is elevated at the outer edge (figure 13) to stop the vehicle from skidding off and rolling over while traveling at the design speed. There are 3 different methods of providing super elevation. Pavement revolved about their center Pavement revolved about their inner edge Pavement revolved about their outer edge
Review examples from course pack
pgs 151-153, 161-178, 194-215, 228-243
Thematic Layers in GIS
see page 180 for diagram
Prismoidal Method, Borrow pit volume calculation, and Contour Area Method
see page 194 for formulas
Highway Curves: Tangent (T), Long Cord (C), Mid Ordinate (M), External (E), Length of Curve (L), relationship between R & D, and Chord lengths for Curve layout
see pages 217-219 for formulas
Vertical Curve Equations General equation, High Point and Low Point Location
see pages 223-225
Lines
A line joins two points, and a string of a spatial sequence of commencing lines, In vector model, they are defined by the order of coordinates, In raster model, they are defined by a series of grid cells, Examples: center line of road, pipeline, center of narrow streams
Geographic Information System: Difference between CAD and GIS
CAD is used for a large scale map/ drawing, which require higher degree of precision, e.g. drawing of machine parts, plans/sections of engineering project etc, GIS is used to model ground features and conduct various types of analyses, GIS can determine spatial relationship between various features, All CAD files can easily be transferred to GIS system
Grade Transfer
Carpenter ‟ s level String level Batter-boards Rotating laser Fixed direction and slope laser Surveyor ‟ s level, or total station Machine guidance techniques GPS, laser, total station
Contour Line Characteristics
Closer spacing indicates steeper slopes Usually, every 5th contour is labeled with an elevation Contours don't pass through buildings Contours are straight and parallel lines passing over built areas, Contours deflect uphill at valley lines and downhill at ridge lines, Ground slope between contours is uniform, Contours tend to be parallel on a uniform slopes
Cross-section and Profile
Contour maps can be used to make cross-section and profile of the ground along any line/route. Cross-sections are taken at the points right and left of the baseline in perpendicular direction. Profiles are taken at the points at defined interval along the baseline On the other hand, elevations of the cross-section and profiles can directly be plotted on the map to get contour lines.
Contours
Contours are lines that connect points of equal elevation, Contour intervals are the difference between elevation values for two consecutive contour lines. Contour intervals are generally set as double of the elevation values that we desire for the ground features, Contours can be plotted manually Using interpolation technique based on distance, Using set square and scale. Using rubber band, Whichever method is used, details of the data mentioned in the field note help a lot while making contour lines, Contour lines are labeled for each line or are thickened for every 5th line and that thick line is labeled. The later is common in practice, In digital plotting and mapping, computer programs automatically plot the contour lines based on DEM.
Graphical Method
Count number of square grids enclosed in the area (N), Find out the scale factor per grid (SF) A = N . (SF)2
End Area Method
Cross-sections are useful in determining the volume of cut and fill in construction (figure 3). End area for particular station is computed based on cross-section and design level. Area might be in fill or in cut. If final construction level is above the ground, it is fill and vice versa. Based on the end areas, volume of earthwork can be calculated by simply averaging the end area and multiplying with length.This method is valid for uniform sections where mid-sectional area is close to the average of the two end areas. For specific earthwork quantities other more precise methods are used. see page 193 for formula
Roads/Highways Classifications
Local - provides access to properties Collector - provides access to properties and connects locals to arterials Arterial - provides a relatively high level of traffic movement; connects towns; connects collectors to freeways Freeway - highest level of service, given by controlled access highways
Machine Guidance and Control
MC Motorized Total Station High level of accuracy, e.g. final grading, concrete pavement etc. GPS Earthwork grading for highways, shopping centers, airports etc. (lower level of accuracy) MG Rotating lasers Laser beam rotates at pre-defined horizontal or inclined plane that helps the machine operators to know the further extent of excavation/filling. Sonic responses Total station GPS
Georeferencing
Georeferencing is an important part of GIS data management, Georeferencing helps shearing of database between different agencies. Commonly used gereferencing methods for North America is Lambert Projection (we will study this in detail in Control Surveying), Transverse Mercator Projection, Universal Transverse Mercator (commonly used in Canada). All projections are defined in terms of grids that include easting and northing.
Characteristics of UTM
A zone is 60 wide. Therefore there are 60 zones, Equator is at 00 latitude, False easting of CM is 500,000 m, Northing of equator is 0 m, Scale factor at CM is 0.9996 i.e. 1/2500, Zone 1 is at 1800W to 1740W, Zone 60 is at 1740E to 1800E, Projection limits of latitude are 800S to 800N
National Map Thematic layers
Almost all places in the US are covered with 1:24,000 scale GIS map (except some parts in Alaska). Because of various possible natural and human induced disaster events, the need of GIS map is overemphasized. GIS based map is a very useful tool for rescue operation during disaster events. Following are the thematic layers of a national map, Administrative Boundaries (state, county, territory) Elevation (contours, shaded relief) Geographic names Hydrography (stream networks, water bodies, wetlands), Land use/land cover, Orthoimagery (satellite images, aerial images, scanned maps), Other (including land surveying, township boundaries, parcels Structures, Transportation (roads, railroads)
Control Survey: Lambert Projection
An imaginary cone is placed around the earth so that the apex of the cone is on the earth's axis of rotation above the North Pole, for northern hemisphere and below the South Pole for southern hemisphere projections. East west direction is relatively free from distortion in this method. Therefore, states longer in east-west direction are projected with this system, Scale is set for 158 miles of N/S distance in this method.
Coordinate Method
Area (A) = Area2 - Area1, Area2 = 0.5 x (X4 + X3)(Y4 - Y3) + 0.5 x (X3 + X2)(Y3 - Y2) Area1 = 0.5 x (X4 + X1)(Y4 - Y1) + 0.5 x (X1 + X2)(Y1 - Y2) 2A = {(X4 + X3)(Y4 - Y3) + (X3 + X2)(Y3 - Y2)} - {(X4 + X1)(Y4 - Y1) + (X1 + X2)(Y1 - Y2)} 2A = ( X coordinate ( Y coordinate of forward station - Y coordinate of backward station)) i.e. A = 0.5 ( X ( YF - YB)) review diagram from page 191
Simpson's One - third Rule
Area = End Area+ X/3(h1+hn+2Ehodd+heven) see page 192
Areas and Volume Calculations: Coordinate method
Area = End areas + X(h1+hn/2+h2+....hn-1 ) Where, X = Common interval between offset lines h = Measured offset distance n = Number of offset measurements
Area measurement by planimeter
Area can be measured by using a device called planimeter. Take a planimeter. Fix one arm of planimeter at any point in the area. Set the revolution counter of drum to zero. Trace the outline of the area by using other arm. Revolution of the drum will directly give the total area.
Cross-sections derived from contour
As done in profile, cross-sections can also be prepared from contour map, For it, mark the required points at left and right of the baseline, where cross-section is required. Then, interpolate the elevations based on the contour lines
Topographic Surveying and Mapping: right angle offset method
Baseline is laid out with stakes at equal interval (100 ft or 30 m in general), Offset distances are measured from baseline to the particular ground feature and the station chainage for that offset is noted down, Sometimes, if the area has dense features, two parallel baselines are laid and offset distances are measured from both of them, whichever is closer, relatively old
Storage and retrieval of data
Data obtained from the sources mentioned above are stored in a computer memory or database system. Those stored data can be retrieved in various forms. The stored data are given a spatial distribution through georeferencing
Plans
Engineering plans show existing terrain conditions only, along with the proposed alterations in existing topography, They are larger in scale compared to maps, Intermediate scale, 1:2,000 to 1:10,000 Large scale, 1:10 to 1:1,000 Plans are usually prepared by using autoCAD programs and digital plotters. Some of them are still prepared manually.
Features
Features contain spatial locations and their attribute tables, There are three different types of features, Point (0 Dimension) Line (1 Dimension) Polygon or area (2 Dimension) Surface or area plus slope (3 Dimension) Spatial data are arranged in different coordinate systems, Rectangular coordinate system (vector model) Grid cells (raster model) Postal codes Milage posts
Components of a GIS: Data collection and input
Field survey Remotely sensed images (satellite images and aerial photos) Digitization and scanning of the existing paper based maps, plans, and photos, electronic transfer of data from various sources, computer networks or CD/DVD ROMs
Plotting Plans
Fix the size of drafting paper based on the scale of survey, Set title block on the lower right corner, First, plot the survey control points (if manually plotted). It is always worth to plot the data outline roughly first to check whether the sheet of paper covers all required features or not. Plotting with coordinates will help setting scale in this regard, Generally, north is vertically upward and should be shown in the map/plan. In grid system, northing line shows north directly, which is nothing but the vertical lines, If a computer is used to plot the data, the graphic code function directly plot the points of same code and connect to depict them exactly as in the ground, Spot heights and survey features are plotted either based on rectangular coordinates (X, Y), or polar coordinates (r, ). After plotting the point, spot elevation is written. In computer aided programs and GIS, (X, Y) coordinates are directly plotted spatially and Z axis (elevation) is labeled through attribute table.
Transformation of Points
For the paper based maps from various sources, coordinates of a number of points are obtained. These coordinates are input in the attribute table using "transformation" tool of the software (e.g. ESRI‟s software), Sometimes, map and aerial photographs are superimposed and transformation is done based on the permanent features such as highways. Shown in figure 2 are three types of transformations
Spatial data representation
GIS software can easily convert raster to vector and vice versa. Field data with x, y, and z coordinates are vector data. Remote sensing data such as satellite imagery are raster data. Shown in figure 5 is a map (a) represented by a vector data (b) and the same map represented by a raster data (c), To conduct any analysis and calculation, we need to convert vector data to raster, Both data models can be used to make thematic layers.
Database Management
GIS system consists of a large amount of spatial (x, y, z) and non-spatial (attribute table) data. A database management scheme in GIS provides help for management of data in a well arranged manner, Data in attribute table are managed in 2D tables (rows and columns). Searching and analysis of data can be done based on the portion of each data in these tables, If similar data are available in two different tables, they can be joined to yield a separate table. This way, any number of tables can be related to each other if they share same table. For example, we can easily join and perform GPA calculation for these separate tables based on student ID, as shown in Table 1, Query of each database can be done using SQL language. For example student ID 10000000015 in EGCE 214, Any other spatial analysis can be done using this query language.
Combined grid factor = Elevation factor x Mp
Grid Distance/Combined Factor= ground distance
Use of grid coordinates
Grid factor = Elevation Factor x Scale Factor
Typical Highway Cross Section
Highways are laid out at 100 ft. interval, places at BC, EC, TS, ST, BVC, EVC, and low points. Curves are laid out at 50 ft. interval. Centerline is staked out at 1/3000 leveling accuracy. Stakes at edge of the road are set in such a way that they slope towards the centerline. For location of slope stake, we calculate the points based on the design cross slope of the sub grade level.
Compound Circular Curve
If the radii of curvature of the curve are different, as shown in figure 6, when the curves of two different radiuses are connected, they are called compound curves. They are used to smoothen the curve for the desired speed in special topography/circumstances. see page 220 for diagram
Mass haul Diagram
In highway construction, to reduce the cost and for aesthetic and geometric stability, cut and fill volumes are balanced as far as possible. Amount of shrinkage (when compacting soil) and amount of swell (when getting soil from rock) should be considered while estimating the cut/fill volumes. The diagram that shows the calculation of volume of earth is called mass haul diagram (figure 4). This diagram shows the cumulative volume from starting point to that particular station, which is useful in balancing cut and fill while designing the construction
Polygon
In vector model, they are defined by the order of coordinates from the lines that close at a loop. Generally, they are attributed with a single number for one polygon. Shown in figure 3 are the coordinates (vector) and a class (raster) of polygon. Figure 4 shows the same polygon class in raster data, In raster model, polygons are represented by a series of code numbers in a grid cell. Note: In large scale maps, buildings are polygons, but small scale they are points.
Transverse Mercator Projection and grid system
It is done by placing an imaginary cylinder around the earth, with its circumference tangent to the earth along the central meridian (CM), Cylinder is flattened and grids are prepared based on it. Scale is exact at the CM, This projection is done for the states predominantly long in north-south direction, Zone width is generally kept 158 miles, At point of contact by secant projection plane with geoid surface, scale factor is 1.00, at meridian it is 0.9999
Use of Grid Coordinates and Relationships/ Convergence
It is the difference between grid north and geodetic north, It is denoted by " in TM grid in Lambert grid in SPCS 83, At CM convergence is 0, In SPCS 83, for point P see page 152-153
Preparation of Maps and Plans
Maps are generally prepared using cartographic techniques by scribing layers of hard plastic sheets with knife. Separate base map is prepared for each feature or sometimes each color. Printing plates are prepared based on each plastic sheet. Final map is prepared by printing the information of each negative plastic sheet available in each sheet to one base map repeatedly for all layers pertinent to that map. Lately, color combinations and features are set up at digital printers and printing is done based on those negatives set at the computer automatically, Plans are completed in ink on a hard and stable tracing type plastic paper, which is always kept as original. Printing of copies from this original are done by setting the original with special printing paper in a device along with ammonium gas and exposing the set into light (this is called a blue print), Depending on the size of the map/plan area, they are printed in the following standard sized papers
Maps
Maps show detailed features, They are of different scales, Intermediate scale, 1:2,000 to 1:10,000, Small scale, 1:20,000 to 1: 1,000,000. Most of the cases, maps are made in a small scale, Several topographic maps of intermediate level of importance are made in 1:50,000 scale, Detailed maps of cities and towns are available at 1:10,000 or 1:25,000 scale also, USGS maps are available at 1:24,000 scale, Sometimes, overall map of the country may be up to 1:1000,000 scale.
Coordinate Grids
Mercator Cylindrical Projection system defines different coordinates (false northing and easting) for different states of the US, State plane coordinate system 1983 is adopted in the US whereas UTM grid is adopted in Canada, GIS software (e.g. ESRI‟s ArcGIS or Arcview) can easily convert these reference systems from one to the other.
Meta Data
Meta data is the data arrangement system for the spatial data, Meta data should contain, Identification Data quality Spatial data model and reference system Information on attribute Source of data There are two types of data models in GIS Features (vector model) Grids (raster model)
Pipeline Construction
Methods are same as the sewer line lay out and construction
Scale Factor
Mp=Mo(1+x^2/2R^2) Mo=scale factor at central meridian, CM, x=east-west distance of the survey station from CM, R = Average radius of spheroid (all will be given)
Data Analysis in GIS
Reclassification : Using different polygon attribute, two polygons can be intersected and reclassified based on available attribute, Overlay: This analysis is used to compare and construct geographic data by superimposing them. These are used for direct comparison. For example, if we have different layers from population, road, universities, available gas stand, we can do analysis for the location of potential new gas stand. Location : Locational relationships are generally defined by buffering or defining directly the polygons/lines, using plotting tool. E.g. number of school within 2 miles square polygon. Connectivity : This analysis is used to analyze the shortest or fastest route, lands touched by utility lines, effects of the maintenance in one road on the other roads, watershed analysis, stream networking, traffic study etc. Adjacency This analysis is used to know the infrastructures on adjacent features. For example, roads adjacent to Cal State Fullerton (polygon), restaurants on the cross street of Nutwood and Commonwealth, etc. Coordinate Transformation: A separate file can be added to the database and transformed it based on the coordinates or scale of existing map. Other analysis: Boolean operations are useful for any type of analyses. We can directly write VB script on the operation dialog box which can do any type of simulation.
Elevation Factor
Sea level (S)/ Ground Distance (D)=R/R+h. h= elevation from mean sea level. R= radius of earth (r&h will be given)
Field Procedure - Curve Deflections
Set the station for PI and stake it out. From PI, using , stake out two tangent lines at both sides of PI. Distance at each side should be longer than T. Compute the values of T, L, BC, and EC. Compute deflection for every 20 m interval of chord length, and odd curve lengths at the beginning and the end. Compute the equivalent chord lengths for those lengths. Set up equipment at BC, and set "0" at PI. Check whether EC is at /2 angular distance or not. Stake out the points based on chord distance and angle (angle of each chord), using tape and total station set at BC. Measure chord length from last stake to EC to verify the accuracy of the layout. Check the layout visually. The curve should be symmetrical
Building Layout
Set x and y on the front property line based on the dimension of the building. Set up total station at x, sight y, set 0 and turn 900 and set the stakes at points A and B (based on the dimensions). Stake them out. Set up the total station at y and set 0 at x. Turn 900 and set up points C and D based on the distance from y. Check whether they are perfectly staked or not by measuring the diagonal. Offset the batter boards at about 6 ft from the building corner and set the batter board at the first floor level. Place nail on top of the batter boards as follows. Set up the Total Station at A, sight B and set nail at 2. Transit the telescope and set nail at 1. Sight C and place nail at 5. Transit the telescope and set nail at 6. Set up the Total Station at D, sight C and place nail at 3. Transit the telescope and set nail at 4. Sight B and set up nail at 8. Transit the telescope and set up the nail at 7. Note down, offset of each batter board from the center line. Elevation of each point (1 through 8). Elevation of the footing. Elevation of the first floor. Elevation of the second floor.
Construction Surveys: Grade
The word "Grade" is used for three different purposes: To refer to a proposed elevation To refer to the slope of a profile line (gradient) To refer to cuts and fills - vertical distances above or below grade stakes
Transportation (GIS-T)
This includes all transportation networks, The traditional reference based on milage/station is completely replaced by coordinate system and cross streets, Cross streets are referred as nodes in the network, Most of the highway data in the US are already in GIS format, Linear features of the highway data consist of spatial location of the highway in a vector form and attribute table for the properties of each highway. The center line of the vector data represents the center line of the highway itself.
Universal Transverse Mercator (UTM) grid system
UTM is same as TM grids system but zones are wider - 60 longitude, It is used worldwide. Scale factor at CM is 0.9996, UTM zones are numbered 1 to 60 beginning at longitude 1800W. US territories are with zone 1 - 20, and Canada is at zone 7 - 22, Easting is 500,000 m false east at CM, and northing of 0 at equator
GIS affiliates/ Automated Mapping/Facilities Management (AM/FM) GIS
This system is used for the management of public infrastructure and utility system, This includes separate thematic maps for different utilities, such as roads, pipelines, cables, etc, Each map has all required database in attribute tables, These maps are prepared based on the infrastructures captured from CAD drawings and pertinent reports. Development of a system using AM/FM technique can control the entire project/office.
Topology
Topology describes the relationship between geographic features (polygon, line, and points). Topology makes GIS based analysis and query possible Topology makes GIS superior than CAD, In topology nodes are intersection of arc segments/ lines, Topological relationships include, Spatial distribution Proximity Connectivity Adjacency Containment
Radial measurement method
Total station or theodolite is set at a traverse station, Azimuth of the particular ground feature point and distance from the traverse station to that point is noted, Easting, Northing, and Elevation are calculated and plotted.
Vertical Curve
Vertical curves are used to provide gradual change between two different adjacent gradients, as shown in figure 8. g1 = slope of lower chainage grade line. g2 = slope of higher chainage grade line. BVC = Beginning of vertical curve EVC = End of vertical curve PVI = Point of vertical intersection between 2 grade lines. L = Length of the vertical curve which is projection of vertical curve into a horizontal surface (plan distance) A = Algebraic change in slope direction (g2 - g1) see page 222 for diagram
Plan and profile
We need to find out property line first by searching for the property markers. Then we set up street line ( SL ) based on it. Sometimes mortgage survey plan helps to find out the street line. Based on the street line width, center line of the street can be established. Offset stakes are then established at both sides of the center lines up to the curb, based on the cross section. Elevation of each station along the center line is calculated based on the gradient. Stakes are then driven at about 3 m outside the curb points. A grade sheet for the stake elevation is prepared and cut/fill is calculated based on the design. Sometimes cutting/filling (grades) are written on the grade stake directly.
Digital Plotting
X and Y coordinates are plotted in a high resolution graphics screen using various programs like CAD and GIS. Those plotting/maps can directly be printed on the paper of any size, Depending on thickness of pen and ink color, lines with different color or different thickness can be drawn, With the state-of-the-art total station, digital plotting is very easy and quick.