Urban Road Design
In a rural road design cross section we normally design from the center line. Typically we set our road pavement to slope from the center at about -3% for the width of the road. We would then hang off a shoulder and then slope to the natural surface and maybe include a drain for drainage purposes. In the Urban situation we often have more constraints that we must design for. Typically we already have existing buildings or other utilities along the existing road edge that we must fit the new design into.
In this tutorial our client has supplied us with some raw data picked up with a total station. They have picked up points along the existing road center line as well as points along the bottom and top of the existing kerb drain; as well as some existing foot path. We have also been supplied with three string files that define the new center line as well as the bottom of the new kerb and gutter. This data is found in the job "UrbanRoad". As the data consists of random shots; ie not picked up in cross sections we will do the following to create the new design long and cross sections.
The job
Bring up the job "UrbanDesign" in Ezicad. If we triangulate and contour the job as supplied you will find that the triangles cross over the drains both to the left and right of the job. We need to define some break or discontinuity lines that will correct the triangles for us. Looking at the job you will notice that the kerb points have been coded for the top and bottom of kerb as "tkerb" and "bkerb" respectively. This is good as we can use this to create some break-lines that can run along the top and bottom of the kerb. However the field party has not differentiated between the left and right kerbs. In this case we will massage the coding in the office to fix up the coding so that we can have both left and right top and bottom's.
We will select the points along the left bottom of kerb and change these first. Under the "Points - Select by Range" menu item select the code points that have a code of "bkerb". You will notice that points on both the left and right hand side have been selected. To only select the left hand points now do a select points by polygon command. Draw a polygon so that it only contains the left hand side points. As we already have some selected points the program now presents us with some options on how to select the data. Select the AND option as this will only select those points already selected as well as those points in the polygon. Ie we only have the left bottom of kerb points selected. Now run the Points - Alter option and change the codes on these points so that there code is "lbkerb". Repeat for the points on the left top of kerb as well as those points on the right hand side on both the top and bottom of the kerb. We are now in the position to run feature coding to create some string lines along these respective kerbs. Fill in the feature coding as below
You will notice that the strings are placed into the discon1 folder so that the program will recognize it as a break line. Press the "Apply to DB" button to create the string lines.
We can now go and recreate the triangles. You will notice that the triangles now lie along the left and right kerbs. I have also taken the liberty of manually adding in a couple of triangles at the top right and bottom left of the job. This option is under the "Contour - Edit Model _Add Triangles" menu item. The two triangles added in were 40,46,39 and 18,4,19. Also now create some contours to check that the triangles adequately represent the job. The contoured surface is shown below.
On inspection the surface representation appears reasonable. We can see a ridge representing the center of the road as well as the kerbs to the left and right together with a footpath to the outside. We are now in a position to run the interpolate profiles and sections. Select the string des in the lots folder. Run the interpolate profiles and sections making sure that the "Include string intersections on sections" tick box has been ticked. Ticking this will ensure that the new left and right design points are added to each cross section. Detailed instructions on the interpolate profile and sections item will be found in a previous tutorial.
Show the interpolated sections by displaying the section view and scanning each section in turn. In this case we are happy with what we see and will accept the sections. If there are any problems the base triangle surface may need extra break lines etc. It should be noticed that in this case the existing kerbs are to be dug up. Often in an urban design the existing kerb and gutter is kept and the center of the road is stripped and re-graded. In this case the design for the left and right edges simply follows the existing kerb profiles.
The Profile Designs
We are now in a position to use our design skills to create design profiles along the design center line as well as the left and right kerb profiles. The most confusing aspect to most people using Ezicad standard is how the road parameters are set up to show and design the appropriate profiles and sections. In this case we have three design profiles; the design center line as well as the left and right kerb lip. We are first going to set up the reference lines which show the respective profiles. Press the P button or select the "Road - Natural Profile - Profile Parameters" menu item.
As we have three lines we will fill in the parameters as follows. The first row (1) can refer to the center line. Any point with offset 0.000 will be picked up on this line. The left design is defined by those points with a code of "desleft" while those to the right are defined by "desright". Fill in the parameters as seen below:
We also would like the center line to be displayed in black while the left is to be displayed in color red while right is to be displayed in color green. In the parameter screen click on the plot button for lines 1 to 3 and fill in the respective color's. If we now display the profile view we have the following. Please remember we have a large vertical exaggeration here:
In this design we are going to drain water from about a third the distance along the designs. To do the design you need to turn on the respective design lines in the road parameters. Below show's the design parameter screen setup to design the left kerb; ie design line 2. Please take note that the Active Line edit box is set up as active line 2. When you are designing line 1 set it to 1 and for line 3 set it to three. Also set up the design colors to be black, red and green respectively to match the reference line colors.
After doing the respective designs we have the following display. The reference lines are shown dashed. This can be set up back in the reference parameters.
The Cross-Section Design
We are now ready to display the cross-sections for the appropriate chainages (stations in the US). The first thing is to define the section parameters in the road parameters. Press the XSection key (has a green X with sect written below it). Turn on line 1 and define it by road 1. Delete any layers etc that are defined here. The layer bit is set up automatically by profiles and section interpolation. Here it is better to set them ourselves.
We are now in a position to define our template cross-sections. In this example we are going to start from the center-line. On the left side we are going to join across to design line 2 and then draw in a drain and join up to the left most edge of the cross section. This example is going to achieve this by hanging a single template off the left and right of the center line. We are not going to hang templates off the left and right kerbs.
An alternative method is to hang templates of all three of our design lines. The cross section templates can be joined together via the wild intersection template instruction. In earlier versions of the program this was the only method available.
To create the design cross sections we now have to design the templates to be used as well as define the template positioning table that defines were each template is hung from. We will start by designing standard template 1 which is hung to the left of the center-line. The template instructions used are
The last line is defined as a cu batter. We are going to go through the program manually and modify the end position of each template. For this design where we only have about 7 cross-sections this is the quickest way to achieve our desired section. If you had a larger job you could design another line along the left and right edges and join to this line. A screen dump of the left template is below:
Fill in standard template 2. In this case we are joining to Design Line 3 at the second line. Everything else is the same. We can now fill in the template positioning table. Before doing so I would suggest turning of profile reference line 1 and profile reference line 2. Also turn off the respective design lines. Bring up the profile positioning table. This is done by right clicking in the section view and selecting the template positioning menu item. Fill in 1 for line1 left and 2 for line 2 right.
We can now review our design by stepping through the sections. The first thing to notice is that the end of our line does not join to the left and right edges of our job. To achieve this right click in the section view and select the "change left and right intersection" menu item. Fill in the offsets for left and right. Repeat for each section. A typical section is seen below.
The design has been completed. You should now check the grades to check whether they are within allowable ranges. For example the pavement grade at chainage 0.000 is a grade of -5.8%. To change the design you simply have to change the profile designs to match your required output. For example to change the right kerb profile; in road parameters bring up the profile design and turn on line 3 and make line 3 the active design. In the profile view you can then adjust your profile design accordingly. In the section view you can see the changes by scrolling through the sections. You can now print out your sections and present them to your client.