Centerline Editor

This command allows you to enter new centerlines (alignments), as well as recall and edit existing centerline files. Centerline files in SurvPC are ASCII files with a *.CL extension.

Note: The format and precision of the station values is controlled through the Job Settings - Station Display setting.

Note: Centerline geometry can be graphically inspected through the Draw Centerline command and imported from other sources using the Utilities - Centerline Conversion command.

• Clear: (icon) Located to the immediate left of the Orange Back Arrow is the Clear button that empties all information from the dialog in preparation for entering a new centerline.
  More Information

  

  Upon the clearing of any centerline data, two additional options are available for creating centerline geometry:

  • PL: With this option, you can generate a centerline by picking any screen polyline (including those with arcs). When you choose Pick PL, you are immediately presented with the graphic screen:

    

    When you select a polyline, it will highlight as a darkened polyline. A Reverse button is also available that lets you see or change the direction of increasing stations.

    Note: Within the Pick Polyline screen are other common controls; most notably the various Map Screen View Controls.

  • PTS: With this option, you can pick a starting location for the centerline which can then be further defined through the Draw Polyline functionality.

    

    Note: Within the Pick Points screen is a Green Enter button and other common controls; most notably the various Snap Controls.

  Pressing ✅ returns to the normal centerline dialog box.

• Start Pt ID: Specify an existing point number (if applicable) of where the centerline should start.

  Note: The starting point can also be specified using the standard Point List or a Map Screen pick options.

• Start Sta: Supply a desired starting station (or chainage) value for the centerline (entry of the "+" symbol is optional).

  Note: The formatting of the stationing is governed by the Station Display setting.

  Note: If you change the value of the start station, all the stationing for the remaining segments will change accordingly.

• Northing, Easting: If the northing and easting are not recalled from a starting point number, you will need to enter the northing and easting for the start of the centerline.

  Note: If you change the value(s) of the starting Northing and/or Easting, the coordinate(s) of the additional segments will shift accordingly.

• Load: Launches the standard File Selector that allows you to load an existing centerline for review or edit.

  Note: SurvPC will automatically check the integrity of the centerline file and the user will have an opportunity to verify the data if errors are detected.

• Add: Permits new segment geometry to be added to the centerline:

  

  Element options include:

  • Line
  • Curve
  • Spiral, Curve, Spiral
  • Spiral Only

  Typically, you will start with a line/tangent segment, but you can also start on a curve or spiral curve element.

  More Information

  Note: The following generalities are assumed based on the element type(s):

  • Lines/Curves (Arcs):
    1. Point locations can be established using existing point numbers or through the standard Point List or a Map Screen pick options.
    2. A Tangent to Previous Element toggle can be enabled that forces the direction of the element to be consistent with the outgoing direction of the preceding element.
  • Spirals:
    1. The known spiral length(s) govern(s) the creation of the spiral(s).
    2. For explicit Spiral-Curve-Spiral geometry, the exit radius of the outgoing spiral is assumed to be infinity.
    3. For Spiral-Only geometry, you have the option to choose the type of element that the spiral transitions into.

  Line

  

  A tangent section (line) of the alignment. This option allows you to enter a Point ID or coordinates to define the end of the tangent, or enter the Station, or Length and the Direction.

  Curve

  

  A typical circular curve section (arc) of the alignment. The first element of the curve defines what the options for the second element can be.

  • RR: When enabled, the RR toggle allows the user to use Railroad curve definitions.
  • Review: The Review button allows you to verify the Tangent In/Out bearings or azimuths (depending on Angle Display settings), as well as confirm PC/PT coordinates before continuing entry of new elements.

  Spiral-Curve-Spiral

  

  The Spiral-Curve-Spiral element is really just two implementations of Spiral Only (i.e. line-spiral-curve and curve-spiral-line). The advantage of Spiral-Curve-Spiral is that it completes three elements at once and is a fairly common application on high-speed highways. This routine also allows the user to define the geometry using known points as long as the Spiral In/Out lengths are entered first.

  Spiral Only

  

  The Spiral Only element will handle a spiral between any line and arc segment (e.g. line-spiral-arc or arc-spiral-arc).

• Edit: Use this button to modify the selected (highlighted) element.

  Note: The data for the type of alignment element will appear in its respective dialog box as discussed in the Add section above.

• Delete: Use this button to remove the selected element.
• EQ: The EQ button allows you to enter station equations (station discontinuities) within the alignment.
  More Information

  

  • Settings: (icon) Use this button to expose a dialog (not shown) with one option:
    • Use Applied Station for "Station Back": When enabled, equations that follow a previous equation factor in the previous equation's discontinuity.
  • Sta Back: Indicate the station along the alignment where the station discontinuity occurs.
  • Sta Ahead: Indicate the new station value at the discontinuity location.
• Save As: Launches the standard File Selector that permits the data to be saved to an existing or new *.CL file.

Note: You can create new points with Centerline Editor. When you enter and save a centerline, it will prompt:

You may answer Yes and save point IDs for key locations of the alignment geometry.

Note: Points are not stored to the centerline file itself, so after loading a stored centerline, no point IDs will appear.