CE 453 Lab #8Page 1 of 8

VERTICAL ALIGNMENT AND SUPERELEVATION

PROBLEM:

In this week’s lab you will continue to hone your Microstation and Geopak skills by establishing a vertical alignment for the relocation of US 20 in Hardin County.

The goal of this lab is for you to establish a vertical profile along the new alignment for US 20. You will also develop the superelevation and existing ground cross sections for this alignment. All vertical curves, cross sections, and superelevation must meet the standards of the Iowa DOT and AASHTO for a rural four-lane expressway. Your design is to be in the metric system. Use the following criteria for your design:

  • Maximum grade = 4%
  • Design speed = 110 kph
  • 4-lane divided rural road
  • 17.2 meter medians (inside shoulder to inside shoulder)
  • 3.6 meter lanes
  • 1.8-meter inside shoulders
  • 3.0-meter outside shoulders
  • Foreslopes
  • 6:1 (from edge of shoulder to 9.0 m from EOP)
  • 3:1 (outside 9.0 m from EOP)
  • Backslopes
  • 2.5:1
  • Median foreslopes
  • 6:1
  • 1.5 meter depth of ditch (below outside edge of traveled lane), 3 meter width
  • 2% normal crown for lanes, 4% shoulder slope
  • Pavement thickness – 0.3 meter
  • Maximum shoulder roll-over – 8%

PROCESS:

You will need to follow the process as outlined in your Geopak Training Manual, with some modifications as set forth in these instructions.

Save the filespatshape.dgn and XS.dgn from the lab 08 folder on the class lab web site, to C:\user\yourname. Activate the Geopak Project Manager work flow and select Vertical Alignment. Instructions on the vertical alignment generator are in Chapter 9 of the training manual. You should now have the Profile Generator dialog. Check it to be sure it is showing the 2001 metric format. If not, go to user>K values, then file>open and select the correct set of K values.

Zoom in to the beginning of your profile view. Set the station for VPI 1 at 100+00, then use the dynamic button to set the elevation to match the existing ground (on your existing ground profile). Click on the Insert After button to move to the next VPI. Continue to place VPI’s, using the Dynamic button, until you reach the end of the profile. While you are doing so, monitor the bk grade and fd grade windows to be sure your grades are at least 0.4% and not greater than the maximum grade of 4%. Also monitor the lengths of grade (the L window) to try to keep the grade lengthsreasonably balanced. As you put in your vertical alignment, try also to maintain a balance between cut and fill. Finally, try to coordinate your vertical curves with the horizontal curves along this alignment. Using the process in the training manual, establish the vertical curves to meet the minimum and maximum “K” values, noting that typical design practice is to use a vertical curve length that is even and a multiple of 5 or 10 meters (i.e., 45 meters not 43.2 meters). Close the Profile Generator as per the training manual.

Follow the steps in the manual to draw the proposed profile. Update the project manager with your new profile information.

The next step in the design process is to draw the existing ground cross sections. Open drawing patshape.dgn.

Activate Geopak and open the project manager (you may have to set up a project number first).

Go to Define and set the plan view to show the current path to your design file. The dialog should look like the figure below, except for the name of the design file and the end station. Click ok to accept the values and close the dialog.

Click on Draw Pattern (on the project manager dialog) and set up a new run called Mainline. Highlight the run and click ok.

Set up the draw pattern dialog as shown below (except use your own job number throughout). Set the ending station to a multiple of 20 meters, such that it is less than the end station of the chain. For example using the above dialog, you would set the ending station to 343+20.

Note that the settings for the level symbology are as follows:

  • Level – Pr pattern lines
  • Color – 0
  • Style – 0
  • Weight – 0

Click on Draw Pattern Lines. Now click on Fit view and then Control+F to save your settings. Finally close the dialog and save your pattern settings as shown below.

Click ok and then open the drawing XS.dgn. Click on the Existing Ground Cross Sections button on the project manager and create a new project. Populate the Draw Cross Section dialogs as follows:

Use your own job number and chain name, where the arrows point.

Be sure that the symbology (display settings and void) are set to the following:

  • Level – Roadway Features
  • Color – 0
  • Style – 3
  • Weight – 0

Click on Modify Surface Settings button (see green arrow above on right side of dialog).

Click on Draw and wait for the cross sections to process. When they are finished processing click on Fit View; you should have a screen full of cross sections. Close the dialog and click Yes to save the XS settings. Now go to the Microstation menu bar and click on Edit>Select All. When all of the images are selected (they will go from green to purple), go to Edit>Lock to lock the cross sections to prevent you from inadvertently modifying or damaging your cross sections. Finish by going to the Project Manager Define button. Select the Cross Section View and set the path to your cross section drawing, as shown on the following figure.

Now select the Existing Ground and make sure the criteria are set as on the next figure. Set the Placement symbology to match the criteria. Click on OK

Next we will set up the superelevation, using the procedures described in Chapter 11. You should reread this chapter carefully, as some of the methods will change since we are now doing a divided highway. Follow the process in the Chapter 11 lab, substituting the appropriate values as given above. Use your beginning station of 100+00. Complete the Chapter 11 process, including defining the plan view shapes in the Project Manager. There is one difference to note in setting the superelevation. When you have completed the settings for calculating the superelevation, be sure that the first slope is positive in both the left and right cases. The dialog should like the one below. If it doesn’t show up like this, just highlight the first line and remove the minus sign from in front of the 2.00. Do this for both left and right. The reason for doing this is to ensure that the high point of each pair of lanes is in the middle, not at the edge of the median shoulder.

In preparation for the lab on quantities, go to the Iowa DOT website and get the summary of awarded contract prices (metric). It can be found at the following URL: When you have it, find a few unit prices that you will need for your design. You should find the prices for the following items:

  • Clearing and grubbing
  • Class 10 Excavation, roadway and borrow
  • Embankment (use selected backfill material)
  • PC concrete pavement
  • Granular backfill
  • Longitudinal subdrain pipe, 100 mm diameter
  • Chain link fence

You will find there are a lot of choices, some of which may not be clear. Two suggestions will help you. First, when looking at several similar items take the one that has the greatest quantity built. Second, unless you know something special about your project, use the average value for the items. Make up a listing of the items you have, with the DOT item number, the full description, and the average unit price. Take a look at the price information for structural concrete, reinforcing steel, and the other items that go into a bridge. Since we do not have a bridge design we will use a budgetary figure of $800 per square meter.

SUBMITTALS:

Include the following:

  • Updated documentation of the design standards you have used to include the source.
  • Hand calculations for one of your vertical curves (centerline only; each of you do a different curve). Include the stations of the beginning and end of the vertical curve, the station of the VPI, and the elevations at even 20 meter stations. For example, if the VPC station is 173+95.18 and your vertical curve is 60 meters long, you should have elevations at 173+95.18, 174+00.00, 174+20.00, 174+40.00, and 174+55.18.
  • Screen print blowup of the vertical curve for which you did the hand calculations.
  • Screen prints (several) of your overall profile, large enough to see details of how you balanced your grades, cuts, and fills.
  • Screen print of several existing cross sections. Be sure to include a cross section at the crossing of the Iowa River.
  • Brief report describing your design process. Your report should include the following sections -- introduction, design criteria, your design process, tabulation of your vertical alignment (grade 1, VC1, grade 2, VC2, etc, which you should print out from Geopak), and your hand calculations. In your report you should discuss any areas that are of concern or that would require more study or information.
  • Include your unit prices in your report. You should set these up in a spreadsheet that you can use later when you have the actual quantities.

GRADING CONSIDERATIONS:

30% Report of process and documentation

20% Hand calculations of a vertical curve.

15% Screen prints of the vertical alignment (profile)

15% Screen prints of the existing ground cross sections

20% Unit price spreadsheet (printout showing the basic layout)