Segment length
This function allows you to determine the length along a segment between two selected points on the segment. The order in which the points are selected on the segment relative to the direction of the segment is irrelevant. In the case of a closed segment however the function cannot operate across the start point of the segment.
To run this function: Choose Inquire > Segment length, or...
Select the start point
Position the pointer and select the first point of interest on the segment.
At the prompt:
Select the end point
Position the pointer and select the second point of interest on the segment.
The Segment length function will continue until the Cancel button is pressed.
Selection of the points displays the details about the selected portion of the segment in the message window as shown below:
String 1, Segment 3, From point 35, To point 55 Chord Length=98.905, Slope chord length=99.030, Chord gradient=-5.0173% Arc length=99.248, slope arc length=99.372, Arc gradient=-5.0000%, Vertical Distance=-4.9621
| Field | Description |
|---|---|
| Chord length | The chord length is determined by summing the horizontal distances between all points in the segment. This is the exact distance as defined by the XY coordinates of the points in the segment. |
| Slope chord length | The slope chord length is determined by summing the slope distances between all points in the segment. This is the exact distance as defined by the XYZ coordinates of the points in the segment. |
| Chord gradient |
The chord gradient is determined using the difference in elevation between the 2 selected points and the chord distances between the 2 selected points, along the segment, as described above. This is the average gradient between the 2 selected points. There is no guarantee that any consecutive pair of points will have this gradient. The units for displaying the gradient are determined by the grade units setting in the defaults file. This can be modified during a session by using the Design Grade function. The units may be either:
|
| Arc length |
The segment may sometimes have portions that approximate a circular arc. This is typically achieved through use of the Circle, Curve Tangent or Curve End functions. Curves are approximated by a number of straight line segments. The arc length reported here is calculated, for curves approximated in this manner, using the arc distance rather than the chord distance around such curves. The arc distance is determined by careful analysis of the segment. Any group of 4 or more adjacent points that are within a reasonable tolerance of being on the same circular arc are subsequently used in the arc distance calculations. Only circular curves in the XY plane are considered. |
| Slope arc length | The slope chord length is determined by summing the individual slope arc distances between all points in the segment. The method of determining arc distances for points on circular arcs is described above. |
| Arc gradient |
The arc gradient is determined using the difference in elevation between the two selected points and the arc distance between the 2 selected points as described above. This is the average gradient between the 2 selected points. There is no guarantee that any consecutive pair of points will have this gradient. The units for displaying the gradient are determined by the grade units setting in the defaults file. This can be modified during a session by using the Design Grade function. The units may be either:
|
| Vertical distance | The vertical distance between the two selected points is the Z value of the second point minus the Z value of the first point. |