Catenary Survey

The Catenary Survey command is most often used with utility/power-line surveys to establish the shape of a cable or wire under its own weight when supported at two points. Similar to the Building Face command, you first establish the vertical plane of the wire through its connection points and then take angle-only observations to interior locations on the curve.

Note: Throughout this section, the term wire will be used and the user is advised this can refer to any flexible item (e.g. cable, string, chain, etc) supported at two ends.

• Start Attachment: Indicate the location of the wire at its first connection point.
  • Read: Use this button to take a current measurement to the attachment in question.
  • Offset: Use this button to locate an inaccessible attachment location through an Offset methodology.
• End Attachment: Indicate the location of the wire at its second connection point.

  Note: Based on the Calculation Method and Segments settings, the routine will attempt to predict the point number of the End Attachment so that the sequence of interior wire point number(s) permits the data to be drawn through easy number sequence (e.g. 101-106).

• Ground Surface: If applicable, indicate the source of any ground surface that should be used as a basis for a Ground Clearance Check.
• Code Prefix: Indicate Feature Code that should be used for all internal wire measurements.
• Calc. Method: Indicate the method by which the catenary curve will be calculated.
• Segments: Indicate the number of segments the wire should be divided into to determine its shape.

  Note: It is suggested that the Segments be an even number (e.g. 2, 4, 6 etc) as this provides a midpoint location to be measured.

  Note: It is worth noting the mid-point location does not necessarily correlate to the location of the greatest sag.

• Check Ground Clearance: When enabled, indicate the minimum allowable height between the wire and any point along the specified Ground Surface.
• Warn When Off Curve: When enabled, indicate the maximum allowable measurement deviation from the calculated catenary curve.
• Auto Turn: When enabled, the robotic total station will automatically turn to the next predicted measurement location.

Upon establishing the Start and End Attachment points, press ✅ and the following dialog will appear.

Main Measurement

• Catenary Report: Located to the left of ✅, the Report button permits the creation of a summary of the catenary curve once enough data has been obtained and includes an option to retrieve current weather in the vicinity based on a current METAR report.
  More Information

  The impact of current weather conditions can have a dramatic effect on wire sag, especially over long span lengths.

  

  • Settings: (gears) When clicked, an optional dialog box is presented that can retrieve an active METAR report for a nearby weather station:

    

    More Information

    • Populate Report Settings with METAR Report: When enabled, indicate the desired METAR station name (commonly a local airport code).

      Note: The Station designation is not case-sensitive and can be simplified in most cases to the three-letter METAR location.

    • Get Report: When clicked, the current weather conditions will be retrieved and presented for review.

      Note: The METAR feature requires an active connection to the Internet.

  • Report Template: Indicate the desired report to produce.
  • Report Format: Indicate the desired file type for the report.
  • Current Temperature: Indicate the temperature that was observed during the collection of the measurement(s).
  • Atmospheric Pressure: Indicate the atmospheric pressure during the collection of the measurement(s).
  • Wind Direction: Indicate the direction the wind is coming from.
  • Wind Speed: Indicate velocity the wind is blowing.
  • Sky Conditions: Indicate the condition of the sky.
  • Attach Custom Logo: When enabled, use the Edit button to launch the standard File Selector that permits a supported image type to be specified.
  • Email Report: When enabled, indicate any recipient Email address(es) that should receive the report.

    Note: Through this option, the recipient will get correspondence from SurvPC Do Not Reply <DoNotReply@carlsonsw.com>.

  Note: The default Catenary Curve report template is located within the PredefinedTemplates\Wire Survey folder.

• Store: When pressed, the current horizontal and vertical angles will be read and used to compute the active wire measurement point. The distance is computed as the distance from the instrument along the horizontal angle where it intersects a vertical plane between the Start and End Attachment points.
• Skip: When pressed, the current wire measurement point can be skipped.
• Fix Hz: When pressed, the robotic total station will revert to the expected horizontal angle of the wire measurement point.

  Note: This is used primarily in situations where the horizontal direction of the instrument may have been jostled while sighting the wire.

Note: Also within the Curve Measurement dialog are other common controls; most notably the various Map Screen View Controls.

Note: Upon completing a span and responding Yes to collect another span, the previous End Attachment becomes the default Start Attachment.