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TO MAKE THE SHAPES (SUPERS) ---AUTOMATIC MODE---
GEOPAK 98 Classic

Geopak represents the superelevation for a roadway design by using a completely unique method.   The user fills out several dialog boxes in order to create an ASCII input file.   This input file is then executed resulting in graphical elements automatically being drawn.   Geopak Corp. refers to these graphical elements as 2 ½ D.   Not to be confused with 3D.

To begin . . . invoke the Geopak User Preferences dialog box:
APPLICATIONS > GEOPAK ROAD > USER PREFERENCES
 

The dialog box below will appear.  If designing in Metric, set the toggles and fields as shown.

Click on SUPERELEVATION PREFERENCES and the dialog box below left appears.   Select the Maximum Superelevation from the option toggle, (shown below right), and release.   Next, click on OK on the SUPERELEVATION PREFERENCES dialog box.   You're now ready to build the ASCII input file.   Critical Length deals with the length of tangent between reverse curves.

NOTE: The Adjust Factor only affects roadways wider than two lanes.

If you needed to add a design speed not already set up in the superelevation tables, you would click on the Superelevation Tables push button and the dialog box below would appear.   Access to this dialog box is currently password protected.   Come see me to have this table edited.

Next, invoke the Geopak Coordinate Geometry dialog box.
APPLICATIONS > GEOPAK ROAD > GEOMETRY > COORDINATE GEOMETRY

The dialog box below will appear.   Select Tools > Superelevation or click the Superelevation icon as shown below.

The dialog box below left will appear.    Typically, FHWA uses the Linear transition mode and distributes the transition over the Runoff Length Only, however Parabolic transition is also available.    If a fixed distance forTangent Runout is desired . . . select Fixed and key- in the amount of runout, (shown below right).

The six fields at the top of the dialog box need to be keyed-in.   In this example . . . an Input File named super2.inp will result from completing this step.    The Dgn File that will eventually contain the shapes, (the 2 ½D elements) will be shape.dgn.   A Baseline (chain) named A and a Profile named vert that are previously stored in COGO will be used.   The Tie (profile grade offset from the baseline) is 0, the design Speed (accessed from Tables) is 60.

At the bottom of the Super Elevation dialog box are three key-in fields and one option toggle, (Dependent/Independent).

Key-in the rate of Crown in the first field.   The first offset field should be set to 0.   The second offset field should be the minimum width of your top of pavement from centerline to the edge of pavement, in this example . . . -5.   The negative designates left.   The toggle can be set to independent or dependent.   In this example . . . the shape on the left will be independent.   When finished with the first side, click on Add.

Fill in the three fields again . . . this time it will be for the right side.   Note that in this example, the right side width is a positive 5 and the shape will be dependent.   ONE OF THE SHAPES MUST BE DEPENDENT, in fact . . . they can both be dependent.   The manual explains this for the curious minded.   When finished with the right side, click on Add.

NOW . . . click on Apply.

If all of your curves and spirals meet the AASHTO requirements for the design speed and superelevation rate selected . . . GEOPAK will now be crunching... building the ASCII input file.   If you have any curves or spirals that are less than the AASHTO requirements . . . Geopak will give you an error statement and will not build the input file until you correct the error.   The dialog box below illustrates an example of an error.

In this example the smallest acceptable radius is 135 meters.   I purposely stored this chain with a couple of 85-meter curves.   As a result . . . the curves (A-3 and 7) and both of their spirals are less than 60 km/h.   These three elements must be stored in COGO at their applicable design speed.

In the dialog box above . . . the command to store the first spiral associated with curve A-3 would be s spi A-3b v 40.   When ENTER is pressed, spiral A-3b will be stored at a 40 km/h.   The next command would be s cur A-3 v 40.   And the final command would be s spi A-3a v 40.

The same commands would be repeated for A-7 and it's spirals.

Now that these elements have been redefined as a lesser design speed in the Coordinate Geometry Data Base . . . Apply can now be pressed again in the Super Elevation dialog box shown on the previous page.   If there are no further design speed exceptions, the ASCII input file will be created.

When the ASCII input file is created, open the DGN file where the shapes will be drawn, (in this example, Shape.dgn).   THEN . . .

Invoke the Geopak Process Cross Sections dialog box:
APPLICATIONS > GEOPAK ROAD > CROSS SECTIONS > PROCESS CROSS SECTIONS

The dialog box below will appear:

Click on Files and select the input file.   You may also create a log file if desired, but for this example the Log File option is toggled to Screen Only.
Click on Apply.

Geopak will now draw the superelevation shape elements in Shape.dgn

For more information on this see, "Pavement Definitions, Cross Sections & Earthwork", Part I, Chapter 12 of the Geopak 2001 Manuals.


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