Create Horizontal Alignment: Element Based
Create a new 2D DGN file and open the file.
To create the horizontal alignment using the most popular method within WFLHD...here are a few tips.
Invoke the Horizontal Alignment Generator:
APPLICATIONS > GEOPAK ROAD > GEOMETRY > LAYOUT ALIGNMENTS HORIZONTAL
...or use the Tools icon below:
The Horizontal Alignment Generator dialog appears as shown. It has 3 pulldowns:
The File pulldown simply invokes the Preferences settings for the Horizontal Alignment Generator.
The Preferences dialog is very useful. It allows the user to preselect the element symbologies for lines curves and spirals, as well as the symbology for the "Modify" tool. This makes it very easy to distinguish the geometric components from each other while laying out the alignment. These symbologies are used only when the elements are NOT stored directly to the GPK. To store the elements as simple, single precision graphic elements, the option, "Save as COGO Elements" (also explained later) must be checked OFF.
To specify the color of these visualized elements... modify the default.smd file via the GEOPAK User Preferences, (Applications > GEOPAK Road > User Preferences > Feature Preferences).
An important thing to remember is that the components never have to be drawn graphically in order to be manipulated later. COGO has several "Visualization" options. It is possible to simply "Temporarily Visualize" a component or components for manipulation or for storing the components as a chain. Graphics just make the .dgn file larger and also limit you to the old world of single precision. The Visualization options can be set on the COGO dialog box. I would recommend using "Temporary Visualization". This way nothing is ever written to the file.
In addition you may also set up your own naming convention for storing the geometric components. This is done under the Category "COGO Element Names".
Under the Category COGO Element Names, you may setup your own naming convention for Points, Lines, Curves and Spirals. The trick here is that the names you key-in will not take effect until this dialog is "dismissed". If the names are left blank, the software will default to the following naming conventions, using the "Next available" name concept:
- Points... (1,2,3...)
- Lines... (L1, L2, L3...)
- Curves... (C1, C2, C3...)
- Spirals... (S1, S2, S3...)
One very important option on this dialog is "Save as COGO Elements", (mentioned earlier). This is what differentiates between whether the components will be stored as graphics (single precision) or as COGO elements (double precision). To save the components directly to the GPK database and as double precision, make sure this option is "checked".
To setup the naming convention for Chains, Profiles and Parcels, there are 2 ways:
In COGO, enter the command "SET NEXT CHAIN main" this will set the next chain name to be main. You can see the current settings using the command "SHOW NEXT ELEMENT".
The names must conform to
the standard GEOPAK convention,
i.e. 1-9 alpha numeric characters
with no special characters.
In the Store Chain dialog, (explained later) type in the chain name you want...that will set the chain name too.
We currently have no plans to implement the Curve Design Tables.
Under the Category Spiral Design Tables, a set of files have been set up to provide the user with an easy way to add spirals (using the AASHTO minimum lengths) to a user defined curve radii or degree. For example, when laying out an alignment using this method, the user simply keys-in a simple curve radius or degree and the spiral length values are automatically populated by accessing this "table" file. This will be explained later.
Under the Category Geometry Settings, the user selects the Curvature Parameter and Direction , as shown below.
Under the Category Dynamic Increments, the user selects the Increment adjustment Values, as shown below.
If "checked" the option Activate PageUp/PageDown shortcut keys will allow the user to increment the elements during design by using the PageUp and PageDown keys on the keyboard.
Design Tables Pulldown
The Design Tables pulldown is where the user sets the paths and file names for the tables to be accessed. We currently are only using the Spiral Curve tables (Metric and English). Once you select the English or Metric Spiral Curve table, select the design speed and number of lanes. The appropriate table will be loaded into the view automatically. As mentioned earlier, these tables correspond with the AASHTO Green Book.
The Tools pulldown is where the user can select a variety of individual tool boxes or simply select the Main tool box for accessing all Horizontal Alignment tools.
Examples Using the Horizontal Alignment Generator
First of all COGO must be running for this to work. No need to worry about this though, because the software prompts you for a COGO session if you don't already have one active. Check your Horizontal Alignment Generator User Preferences settings as explained earlier to make sure that you have correctly selected all of the desired settings. Check to make sure that your Spiral Design Tables are pathed correctly. These tables aren't actually necessary, but make it much easier when using spirals and making sure that you are using the minimum spiral lengths for the appropriate design speed and curvature.
The path (for office workstations) should be set as shown below: Browse to either the Metric or English folder and select the appropriate table file.
Select the Main tool box from the Tools pulldown (as shown previously).
To place a typical SCS, (most common way):
Make sure that "Temporary Visualization" has been selected in COGO. Create the entry and exit tangents, using the Store Line by 2 Points tool as shown below:
Select the Place SCS (Intersecting Elements) tool. Identify the tangents, (follow the on screen prompts). Once the second tangent is identified, the 3 elements of the SCS will appear (as keyed-in in the dialog). To "Modify" the length values, you may highlight one of the length fields and use the little arrows for increasing or decreasing the values. Setting the Increment Values was explained earlier on this page, (above). The position of the SCS can be easily warped into place. When you are satisfied with the location of the SCS...simply data point the screen. If you had "Save as COGO Elements" toggled ON, those components are now stored in the GPK database.
Storing these components as a chain is much easier with GEOPAK 2004. Even though they are not actually drawn graphically... GEOPAK can see them. To store (for example) these 5 components as a chain, invoke the GEOPAK 2001 Store Chain tool.
With GEOPAK 2004 Store Chain there is no need to continuously click until all of the elements are collected. Simply complete the dialog with the Chain Name, Begin Station etc... and data point any component that is visualized and accept it with another data point. All adjacent components will be considered for the chain. You will see several small arrows pointing in a direction. These directional arrows are asking you if this is the direction that you want to store the chain stationing. If this is not the direction, simply click reset and the directional arrows will switch... or as some in the South say..."swap". Once the arrows are pointing the right direction, data point the screen again. The components are now stored as a chain.
You may have noticed that on the Store Chain dialog there is an "Opposing Element" option. The options are Transpose and Create. These options are given because sometimes the components may not be stored all going in the same direction. When you store the chain at a direction and some of the components were stored in the opposing direction, you have the option to have GEOPAK Transpose those offending elements or Create new elements instead leaving the original ones alone... I would recommend using Transpose and keep the GPK file smaller and cleaner.
For a little more complicated example.... Let's place an SCSCS, (an easy way):
There is a "Truncate Back Element"
option available with these tools.
Using it to trim the back
components is suggested.
Make sure that "Temporary Visualization" has been selected in COGO, (shown previously in SCS example). Create the entry tangent, using the Store Line by 2 Points tool, (shown previously in SCS example). Create the first SC using the Place SC Tangent to Line tool.
Create the second SC using the Place SC Tangent to Curve tool.
Create the exit Spiral and it's exit Tangent using the Place ST Tangent to Curve tool.
To create a switchback (delta that exceeds 180 degrees) SCS:
Make sure that "Temporary Visualization" has been selected in COGO, (shown previously in SCS example). Create the entry and exit tangents, using the Store Line by 2 Points tool, (shown previously in SCS example). Invoke the "Place SCS (Intersecting Elements)" tool. Make sure you have "Loop (Exterior Construction)" checked. Identify and accept the first tangent. Identify and accept the second tangent. Pretty simple!
Note: The Modify option will also be available once the second tangent line is identified.
There are many other cool tools available with GEOPAK 2004 such as Place Dynamic Alignment... This tool allows you to pre-select geometric values and design "on the fly". Give it a alt="Screen shot" try.
To Modify the Visualized elements:
Visualized elements can be further manipulated using any of the 4 "Manipulate" tools. Move Plan View Element Rotate Plan View Element Extend Plan View Element Delete Element It is very important to mention that visualized elements cannot be deleted from the GPK file with the normal MicroStation "Delete Element" tool. That tool only deletes elements that are written to the design file. To delete these visualized elements, use the "Delete Element" tool on the "Manipulate" tool box. Of course these elements can also be deleted via COGO key-ins or COGO Navigator.
An output of the alignment can be reviewed/printed as well.
There are several ways to VIEW THE OUTPUT LISTING. After the alignment is stored, activate the COORDINATE GEOMETRY dialog box. In the COGO Key-in field, type DES ALI [chain name]. This produces an output similar to the old RDS listing that many people are familiar with.
In the COGO Key-in field, type DES CHA [chain name].
Use the COGO Navigator (icon), as shown below:
Next select the chain from the Navigator dialog and click the Print/Describe Element icon, as shown below:
This produces the default GEOPAK format output listing.
NEXT...To actually create and print a hard copy of this alignment, using the COGO pulldowns, select File > File Utility, as shown below:
Select Output and type in an Output file name in the field, as shown below:
Note: You are limited to 5 characters in the Output File field.
The actual name of the file that gets created is appended with the name of the .gpk file and the extension, .o[operator code], as shown below:
To display the alignment graphically, (for Final plans) see Display the Horizontal Alignment.