Tech Tips


Road Regression

This Tech Tip explains how to use the Regression function in roads.
 

TechTips

Roads Mode

Alignment Menu > Regression > Extract Alignments

This function allows you to determine the alignments from single or dual carriageways.



The program can determine the various road alignments so you need to select which alignment you want extracted.



For Single Carriageway:

Type of RoadSelect whether the road must be extracted as a single or dual carriageway road
Alignment Elements to extract 
Horizontal AlignmentCheck this option to extract a horizontal alignment
Vertical AlignmentCheck this option to extract a vertical alignment
Super ElevationCheck this option to extract the super elevation
Road Edges from CADCheck this option to extract the road edges (widths)




For Dual Carriageway:

Type of RoadSelect whether the road must be extracted as a single or dual carriageway road
Alignment Elements to extract 
Horizontal AlignmentCheck this option to extract a horizontal alignment
Vertical AlignmentCheck this option to extract a vertical alignment
Super ElevationCheck this option to extract the super elevation
Road Edges from CADCheck this option to extract the road edges (widths)




Accuracy Settings

Vertical Rounding (R)Enter the rounding factor for vertical curve lengths. The calculated curve lengths which will be entered into the vertical alignment spreadsheet by the extraction routine will be rounded to the nearest (R)
Vertical ToleranceEnter the maximum allowable height difference between the ground model and the vertical alignment to be calculated by the program
Vertical Grade Tol.Enter a minimum grade difference tolerance. The program will not add VPI points where the difference between the front and back grades would have been less than this tolerance
Super Rounding (R)Enter the rounding factor for super elevation grades. The calculated grades which will be entered into the edge levels spreadsheet by the extraction routine will be rounded to the nearest (R)
Super ToleranceEnter the maximum allowable difference in grade between the ground model and the super elevation grades to be calculated by the program




Extract elements at offset from CL

Left / Right VerticalSpecify the offset from the centre line where the vertical alignment must be extracted from the DTM. Only available if the Vertical Alignment option is checked.
Left / Right SuperSpecify the two offsets from the centre line between which the crossfall at each cross section must be calculated. only available if the Super elevation option is checked


After making the required settings, click OK. The program with then extract the various alignments based on the settings selected, and the data will be added to the current road file. Once the various alignments have been extracted, further manual editing might be needed.

Note: the quality of the alignments extracted is based on the quality of the survey, so results will vary.

Alignment Menu > Regression > Extract Strings

This function only works with string roads, if your road is still a cross section road an error will appear and the function will not run.



To convert your roads to string roads, go to the File Menu > Select Road File



Then click on Convert all to String Roads, once converted you can run the Extract Strings function. This function allows you to define the stake line and edges of a road from an existing CAD drawing.



Select the carriageway type and which entities must be extracted from the drawing (different options will be available depending on the type of carriageway selected). Click OK to continue.

The program will prompt:



Click on the start point of the stake line. The entity must be a line or a polyline.

The program will now prompt:



Click on the end point of the stake line. Now the program will ask you to indicate the entities that define the stake line with:



Indicate the drawing entities that define the stake line and right-click to display the popup menu:



If the correct entities have been selected click on the Extract String option. You will be asked:



Click on Yes to clear out existing road data or No to just recalculate chainage intervals.

Should you have made a mistake in indicating the stake line entities simply right-click and select Re-define last entity or Re-define.

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