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MX Cross Sections v8i

Terminology

The following terms are used in this document.

Normal Drive - A driveway that is perpendicular or nearly perpendicular to the alignment.

Skewed Drive - A driveway that meets the road at an angle.

Drive with Curves - A driveway that cannot be accurately defined by a straight line.  Refer to Complex Drives & Walk Sections for more details.

Related Pages

Before You Begin

This documentation contains six distinct parts. The first portion, "Drive Preparation" should be skipped if your project does not have any drives. 

The "Normal Drive Preparation" portion should be skipped if your project does not have any normal driveways.

The third portion, "Skewed Drive Preparation" should be skipped if your project does not have any skewed driveways.

The "Sectioning" portion covers the generation of  MX Cross Sections. Near the end is a couple of steps for skewed drives. Skip these steps if your project does not have any skewed driveways.

The fifth portion, "Skewed Sections In MicroStation" should also be skipped if your project does not have any skewed driveways.

The sixth portion, "Drives With Curves" should also be skipped if your project does not have any circular driveways.

Drive Preparation

  1. In a new model (Drive Const), create construction drive center line strings for every driveway on the project, skewed or not.  Use the following command;

Modify > Edit String > Create a String >> Create From Individual Points

Use the Construction PSM to split drive pavements.  String labeling is unrestricted since these strings will only be used in the next step as a source for point selections.

Be careful to contain skew drive center lines within the limits of the existing ground triangulation.  This consideration reduces the chance of obtaining null section point elevations.  Null elevations are not friendly to draw.  Therefore, it is recommended that you display the project's existing ground triangles.

Normal Drive Preparation

  1. Stations for each normal driveway must be added to the Master Alignment string.  Use the following command; 

Modify > Edit Point > Interpolate a Point Onto a String

Use the Intersection PSM to interpolate the new stations where the drive center line crosses the Master Alignment.

Skewed Drive Preparation

  1. If the skewed drive construction lines do not ultimately cross the Master Alignment, then MX tends to error when it comes time to process the "Skewed Station (by) 2 points" option (Step to follow).  If the strings generated for skewed drives in Drive Preparation already cross the Master Alignment, then advance to Step #2 of the Skew Drive Preparation.

    Using the just created construction drive center lines for reference, recreate new drive center lines again but this time construct each line past the proposed roadway's Master Alignment string. Use the following command;

    Modify > Edit String > Create a String >> Create From Individual Points

    Use the Construction PSM to extend each line.  As before, string labeling is unrestricted since these strings will only be used for future point selections. 

  2. Measure the plan distance along each skewed drive center line from it's intersection with the Master Alignment to it's intersection with the proposed edge of pavement.  Note these values for future use.
  3. Stations for each skewed driveway must be added to the Master Alignment string for the normal portion of each skewed drive.  Use the following command;

Modify > Edit Point > Interpolate a Point Onto a String

Use the Intersection PSM to interpolate new stations where the skewed center line crosses the proposed edge of pavement.  MX will determine the closest position on the alignment to the intersection specified, despite the obvious offset.  This interpolated position will be the station of the normal portion of each skewed drive.  Note these stations for future use. 

Step #3 is necessary because the portion of a skewed drive section within the proposed pavement limits is perpendicular (normal) to the proposed alignment, and the skew proper commences outside the pavement limits.  The two parts of a skewed section will later be married together in MicroStation.  Refer to the 17+81 sample cross section in the Construction Plans of the Highway Design Manual.

The XSDetail Add-In

Prior to cutting cross sections, run the XSDetail Add-In to capture detail features such as trees, utility poles and drainage pipes.  This results in a model that will be cut in addition to various existing and design models. 

Sectioning

Cross Sections are generated and may be displayed with the Cross Section Viewer.  This can be found from within MX by selecting Analysis -> Sections -> Create Cross Sections...  The Cross Section Viewer has a toolbar for options available with in the Viewer, a graphics area in which the sections are displayed, and a station selector for navigating to other sections.
Hit the create section button button to bring up the panel shown below  (the tooltip for this button will say "Create New Cross Sections").

Create Cross Section panel

Specify the Reference Model, Reference String and Model to Store Sections.  Verify that the section model defaults are set to the XSU.PSS style set and the XSU.FNS feature set.  Similar to any of MXROAD options, you must ensure that you assign the correct style and feature sets to your models.  These model defaults affect relevant panels in MX, allowing appropriate string identification and selection.

Check the Section Additional Models box and the Limit or Add Section Locations box.  Hit the Next button to advance to the Section Additional Models panel shown below.

Section Additional Models panel

On the Section Additional Models panel, select each model containing data needed for your sections.  A model may be selected more than once to accommodate for multiple section sets.  Set the Description, Mask, SINT, and Offsets for every selected model.  Refer to the following table for the recommended entries:

Cross Section Item Model Description Mask SINT Offset Left Offset Right
Design Surface Design Design Design Tria OFF * *
Existing Surface Triangulation Existing Ground NONE OFF * *
Old Ground Elevation Design OG Elevation XS Old Ground OFF * *
Sill Left Topo Sill Left Building Sill OFF * 0
Sill Right Topo Sill Right Building Sill OFF 0 *
ROW ERW ROW NONE OFF * *
Environment ENV Environment NONE OFF * *
Trees, Poles, Hydrants... XS DETAIL MCxx Detail Features NONE OFF * *
Crossing Drainage Pipes XS DETAIL MCxx Drainage Pipes xs pipe OFF * *

* Default Offset values may need to be increased.  Always section more than you plan to draw.

Setting the Description will assign the appropriate section set label to the strings being cut.  These section sets are automatically drawn by the XS-MS macro.  Since only one description may be used at a time, consider correcting another model's description to make a particular choice available.

If the XSDetail add-in is able to determine that a pipe crossed the reference alignment, then it is given a different string label from the rest of the detail and will be plotted differently.  Refer to Adding Details to Cross Sections for more information about XSDetail.

Right-of-Way and Environmental lines that originated in MicroStation will need elevations attached. This is done with the NHDraper program. See its documentation for more details.

In the Mask section you should specify the appropriate mask table, see String Masking for more explanation of Mask tables.

SINT (Secondary INTerpolation) should be turned OFF for all recommended section sets.  Other circumstances may require SINT.

It is necessary to set the Building Sill Offsets to zero on one side to filter out the opposite sides buildings.

Specifying Section Locations

Section Location panel

The last panel "Section Location", will allow you to control which locations you want to cut.  There are options to cut sections at a constant interval, at a specific station such as a drive or intersection, as well as two options to create skewed sections.  Use the "Add" button to build a list of exactly what you want created.

Feature strings such as Buildings, ROW, or Environmental items are sectioned at the specified stations, and may not represent the closest point to the reference line.

For Skewed Drives

  1. Build entries for each skewed drive with the "Skewed Station 2 Points" option.  Supply both ends of each drive construction center line that was created in Step #2 of the "Drive Section Preparation" section.

Be careful to contain skew drive center lines within the limits of the existing ground triangulation.  This consideration reduces the chance of obtaining null section point elevations.  Null elevations are not friendly to draw in either profile or section.  Therefore, it is recommended to display the project's existing ground triangles.

  1. Build entries for the normal portion of each skewed drive with the "Special Station" option. Supply the station of the normal portion of each skewed drive that was interpolated in Step #3 of the Skewed Drive Preparation section.

Make a strong attempt to identify all areas where a drive or walk might be. It is easier to delete a drive (for instance) then to move all your sections from sheet to sheet and allow for one which was not anticipated.  To save the sectioning criteria for future iterations, select the Save Set-up... button.

Once all the desired section locations are defined, select "Finish" to begin the section generation.  A successful process will usually return you to the Cross Section Viewer.  In the case of a "run time error", don't fret, it just means that the Cross Section Viewer has crashed, your sections should have been cut successfully.  The Cross Section Viewer provides a limited view of the new sections, therefore it is recommended to close down the Viewer.

To draw your cross-sections in MX, refer to the sample XS-MS macro drawing input files.

Skewed Sections in MicroStation

For the skewed portion of skewed drives, use MicroStation tools of your choice to delete all parts of the section within the proposed pavement extents.  Take note that because these sections are skewed, the proposed pavement widths increase with skew angle.

For the normal portion of skewed drives, use MicroStation tools of your choice to delete all parts of the section outside the proposed pavement extents on the drive side of each skewed drive.

Use Move Element to move the skew portion of each skewed drive to it's corresponding normal portion.  Use the "Keypoint" snap and insure that you grab and drop the elements at their ends.

Label the skew portions and identify whether the skew projects ahead or behind.

Now that the skew portion of skewed drives have been joined to the corresponding normal portions, delete any remains of the abandoned skewed sections. 

For Drives with Curves

Refer to Complex Drives & Walk Sections for more details

To draw your cross-sections, refer to MX cross-sections to MicroStation.  

 





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