Road Widening
A common road design problem is the widening and repair of existing road surfaces. In this scenario we wish to fill in the road shoulder and possibly widen the road as well on both sides. To minimize the cost we don't want to change the existing pavement.
The data will be supplied in the tutorial directory. If it is not there please point your web browser to ftp.foresoft.com and copy and paste the file from the pub directory to your computer. The data has been supplied in the cab file "roadwidening.cab". To access the data you need to first open up CDS. Then click on the options menu and then restore data. Select the cab file from the directory you downloaded it to and also select a directory where you wish the data to be restored to. The directory "c:\program files\ezicad\ezicad\tutor" is recommended as your previous tutorial files are found here.
Your version of Ezicad needs to be later than 28th April 2003.
In the following example we have an existing forest road which we need to widen to 3 meters on either side of the given road center line. The field party has picked up points nearly in sections and has also defined for us three strings. These strings are
The first step is to triangulate and contour the surface and check that what we have adequately represents the existing road and surrounds. If you are unsure of how to do this we suggest that you review the procedure found in earlier tutorials. The data as supplied has had this done. The screen shot below shows a section of the road that has been enlarged. It is suggested that you first pan along the road to check that everything is OK before proceeding.
We now need to interpolate some sections from this surface. From the "String" menu use the Select - Single string option to select the existing center line. Once you have done this run the "Interpolate Profiles and Sections" from the "Contour" menu. In this interpolation it is important that we pick up points along the existing left and right edges as well and that the interpolated points have the appropriate coding set on the points. For this to happen it is important that we check the "Include string intersections in sections" check box as seen below:
Once you are happy with the sections produced accept them. We are now in a position to start the design process of the job.
For the current data we have 3 profiles that we can display. We have a profile of the center line. We also have a profile of the left and right edges of the road. These are created from the intersection points of the interpolated sections and the left and right edge of the road strings respectively. The first step is how do we tell the program that these are the profiles we wish to use and how they are used. Click on the road parameter button (big green P and fill it in as follows) Initially it will have been filled in with some default values from the interpolation. We will need the left and right profiles defined for this example.
For this example we are going to work on each of the three profiles in turn. Change the reference profile parameters as above so that only Line 1 is checked. Click on the Design tab and fill it in so that only design line 1 is on. Also make sure the active line is set to line 1. ie as below
We can now display the natural center line. The next step in the process is to design a new vertical alignment. In this case we are keeping the existing road. The design is simply what we have. To achieve this show the profile and right click with the mouse. On the pop up menu select the "Road profile to design" option. The program picks up all the points and uses there chainage and height to fill in the design. Thus the design and the reference line are displayed on top of each other. The profile can be seen below:
The next step is to display reference line 2 which is for the left of the road and create a design which is the same. Go back to the reference screen and check Line 2 and uncheck Line 1 and 3. Go to the design section and check Line 2. Make Line2 the active line. Uncheck Line1 and 3. Bring up a new profile view and create the design again by right clicking the mouse and using the "Reference line to design" command again. Repeat also for line 3 which is the right hand line.
Summarizing so far. We have created sections along the road. We have extracted the profiles of the center and left and right of the road. The next step is to define a road template that specifies our design section.
Specifying the design template
From the "Road" menu select "Design Criteria" and then the standard template option. Select template 1. We will hang this template to the left. The first command is a start command and we will specify X and Y values of 0.0 to signify that the template is hung directly of the center of the road. We wish to maintain the current road section so we wish to join straight across to the left edge of the road. This is achieved with the "Join to design line" command and we will specify a design line of 2 which is the design line of the left of the road. From here we wish to widen what we have until we reach an offset of 3 meters. ie the total width of the road will be 6 meters. We use the "Offset & Grade" command. For the offset we specify 3 meters. However we don't know the grade. Specify a value of 99999 or greater. The program accepts this as a special case and automatically uses the grade of the previous leg. Once we reach the new edge of the road we will put in the appropriate batter slopes depending on whether we are in cut or fill. The completed template definition for the left hand side is seen below:
We need to create a slightly different template for the right hand side. In this case we create a standard template 2. The only difference is the "Join Design Line" command. In this case we wish to join to the right edge of the road. This is design line number 3. The next step is to specify that we are using template 1 on the left and template 2 on the right in our template positioning table. Before doing so check the road parameters again. For our reference parameters we only want Line1 checked which is the center line. From the design tab make sure that Line1 is checked and that the active line is set to 1. On the "CS Reference" tab make sure that only Line1 is checked and that road number is set to 1.
Display one of the sections by clicking on the section icon. It is 16 across from the left on the bottom line of icons. If you right click in the section view you will see the menu item "Template positioning". There will be 6 columns displayed.should be two columns displayed; 1L and 1R which are for left and right respectively of design line 1. If you have any other columns displayed; for example 2L,2R or 3L,3R it means that the design lines are checked back in the "design" section of the road parameters. If so you can either ignore them or go back and turn them off. Fill in a template of 1 to the left and 2 to the right. You only need to fill in the first line. Once this has been done right clicking on a current entry will fill in the rest of the column with the same number.
Go back into the road parameters - the design section. You need to check Line2 and Line3. These need to be checked when displaying the sections. Otherwise the design lines for 2 and 3 are not found and the section will be incorrect.
Displaying the next or previous section will update the section displayed and we should have a typical section such as follows:
As we can see the new design runs along the existing surface but comes out until we reach an offset of 3 meters. We then apply the appropriate cut or fill batter.
We are now in a position to print/plot/export to dwg a set of cross-sections; and calculate earthwork volumes etc.