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Chapter 14 Quantities

 

This chapter shows you how to calculate earthworks quantities and display them on the screen or in a text file. HighRoad calculates earthworks quantities using the end-area method allowing for bulking or compaction and horizontal curvature. Cut and fill volumes are calculated between the existing surface (after any stripping) and the underside of the finished surface layers. HighRoad also calculates cut and/or fill volume between the terrain surface and a datum plane.

 

Earthworks quantities

HighRoad will calculate earthworks quantities when the Schedule of Quantities window is open and the range over which the quantities are required is specified. Stripping will be calculated in conjunction with earthworks quantities if a depth of stripping is specified.

You can access quantities calculations in both the Schedule of Quantities window and the Text window. When the Text window is active, quantities can be listed in this window and saved as a text file. See Listing quantities for details.

 

Overlapping control lines

Where you want to design control lines that overlap, you need to consider how you will handle the quantities calculation in the area where the control lines overlap. We recommend that you use the option to construct control lines. (See Constructing the road) HighRoad will create a terrain model based on the finished surface of the design after construction. Design the first control line, construct it and then design the next. This will allow you to calculate quantities more precisely when you have designed control lines which overlap. If you do not use the option to construct the road then you will need to interpret the quantities produced by HighRoad in areas where control lines (and their batter slopes) overlap.

 

Schedule of Quantities

Choose Schedule of Quantities... from the Window menu. If the chainages between which the quantities will be calculated are specified, a schedule of quantities will be displayed and will list the following items:

* Cut to fill

* Cut to spoil / Borrow to fill

* Stripping to stockpile (if chosen from the Quantities menu)

If you have created an additional strata (such as rock), HighRoad will list the items for each strata. You can specify a compaction or bulking factor to be taken into account for each stratum when calculating the amount of cut to fill and cut to spoil or borrow to fill.

 

Quantities limits

To specify the chainage range, choose Limits... from the Quantities menu, or Quantities limits from the Text window. A dialog box (see Figure 14-1) will appear and you can type the chainages between which the quantities will be calculated.

Figure 14-1

For final quantities, be sure to specify the start and finish of the section of road which is to be constructed. During design, you may find it useful to limit the calculations to a smaller chainage range so that the calculation of the quantities is faster. If you limit the quantities calculations to the area in which you are adjusting the design, you can still see how your changes are affecting the quantities without having to wait to calculate the whole length of road.

 

Stripping

HighRoad can allow for stripping of a topsoil layer prior to calculating the cut and fill volumes. The volume of material stripped is calculated and listed as Stripping to stockpile in the schedule of quantities. HighRoad is initially set up for a strip depth of 100 mm. You can change this depth. Select No stripping... from the Quantities menu. A dialog box will appear and you can enter the depth of stripping you require. If a strip depth has already been specified the menu item will be Strip depth <>mm...

 

Compaction or bulking factor

Most natural material excavated from a cutting will occupy a different volume when it is compacted in fill. This volume change can be specified as a compaction or bulking factor. To specify this factor, choose Earthworks factor... from the Quantities menu. If the material occupies a smaller volume in the fill than in its natural state, specify a compaction factor (for example, 10%). If the reverse is true, specify a bulking factor. This factor is taken into account when calculating a schedule of quantities and when displaying balance levels. If you have created more than one stratum then you can specify a different compaction or bulking factor for each stratum. For more information about compaction or bulking, refer to Earthworks, page 24-2.

 

Interval between end areas

The interval between end areas used for quantities calculations depends on the type of survey data. Where survey data is in the form of a network of points, the cross sections used for end area calculations are spaced at the interval specified the dialog box shown in Figure 10-1. To specify this interval, choose Layout from the Sections menu. For more information about Quantities calculation, refer to Method of calculating quantities.

 

Effect of plan curvature on earthworks volumes

The interval between end areas is measured along the control line. On curves this may not represent the distance between centroids of cross sections. End areas can adjusted to allow for the effects of horizontal curvature. Choose Method of calculation... from the Quantities menu and Text menu. A dialog box as shown in Figure 14-2 will appear. Check the box labelled Adjust end area using Pappus theorem.

 

Figure 14-2

Pappus' theorem is applied using the centroid of the area of cut and fill of each cross section in relation to the location of the control line.

 

Fitted length method

You can choose to list the quantities using the fitted length method. Choose Method of calculation... from the Quantities menu and Text menu. A dialog box as shown in Figure 14-3 will appear. Check the box labelled Fitted length method. This results in the same total volume but volumes are calculated at each cross section rather than between cross sections.

 

Figure 14-3

Printing the quantities

You can print a list of cross section end areas and cut, fill and stripping volumes for part or all of the design. To print quantities information, you must first list the quantities in a text file and then print the text file. Choose Text from the Window menu. An empty document will be displayed. Set up the quantities limits, strip depth and the compaction or bulking factor as required from the Text menu. Choose List Quantities from the Text menu. A dialog box similar to that shown in Figure 14-4 will appear. You can choose which items are to be listed. Save the text file in the usual manner. You can open this text file using a word processor or spreadsheet and create a report or present it in the required format.

Note: If a Text window is already open (for example, the original text file of survey points) it will be brought to the front and become the active window. You can list the quantities in this window (they will be appended to the end of the file). Alternatively you can create a new text file. Choose New text file from File menu.

Figure 14-4

Note: The notation Work not done and Work already complete will appear if you have created a second DTM to be used for earthworks monitoring. This feature is useful for producing quantities of work done on a regular basis, such as monthly quantities for a road construction contract. For more information see Monitoring construction quantities, below.

 

Monitoring construction quantities

Note: This option is available only if you have purchased the license to use the Extra DTM module. This module is included in HighRoad Pro and optional in the other models.

During construction of a project designed with HighRoad you can monitor the progress of the project by measuring quantities of earthworks completed, compared with quantities of work yet to be done.

To monitor the progress of the work HighRoad needs information about the original ground model and progressive information about changes to that ground model as work proceeds. The original ground model is used for the design and it is called Existing Surface DTM. The new DTM that represents the changing surface of the ground during construction will be named by you and will start off being identical to the original ground. This will be referred to as the Progress DTM.

As work progresses new survey information is added each month (or whatever cycle suits your project) to the Progress DTM. As work progresses, the Progress DTM differs increasingly from the original DTM as more new survey data is added. At any time earthworks quantities can be listed and these will show a snapshot of the project at that particular time.

 

Creating the Progress DTM

It is important that roads or pads have not been constructed if you wish to monitor the progress of a project. The DTM must represent the original ground surface before the project commenced. Choose Save as... from the File menu. Name appropriately , for example <My project progress claim 1>. Choose Duplicate DTM from the Edit menu to duplicate the existing ground. A dialog box as shown in Figure 14-5 will appear. The elevation should not be changed. Make sure that it is zero. Check the box marked For earthworks monitoring. Features, especially breakline features, are usually inappropriate for construction monitoring, so you will not need to check the box labelled Duplicate the features as well.

 

Updating the Progress DTM

Update the Progress DTM with new survey data to show the state of construction. Firstly prepare a list of new survey data points .

Note: When preparing a list of points of the new work to be added to the Progress DTM, choose suitable descriptions for points so that they can be identified later, or can be automatically joined by features defined in the feature library.

Figure 14-5

 

Select the Progress DTM from the Active menu. Choose Text from the Window menu. A blank Text window will appear. Choose Open Text File... from File menu. A standard file dialog box will appear. Open the text file containing the new points. Choose Convert text file... from the Edit menu. The new points will be added to the Progress DTM.

Delete or make non-contourable any old points within the area where new points were added. Choose Contours... from the Design menu to specify contour interval and tension. Click OK. The contours on the Progress DTM are shown in blue to differentiate from the green used for the original DTM. The Progress DTM should show the state of construction at the time of the new survey data.

Choose Text from the Window menu to display a Text window. Choose List quantities from the Text menu. A dialog box similar to that shown in Figure 14-4 will appear. You can choose which items are to be listed of the work that has been constructed, and the work still remaining.

Each time you wish to process a new claim, make a copy of the current file (in this case, My project progress claim 1) and save it under a new name (in this case, My project progress claim 2). Progressive addition of survey data will mean the main project file used for monitoring progress will show only the latest construction surface.

 

Balanced earthworks

It is often a design objective to have balanced cut and fill quantities. HighRoad will calculate the level for each cross section which will produce a balance of cut and fill. The level at which this ratio is achieved is shown as a square marker as in Figure 14-6. (The natural surface is also shown.) These points can be used as a guide when positioning the grade line. Minimum earthworks would result if the grade line passed through each point.

HighRoad will calculate and display balance levels for a profile whenever there is survey information and a typical section for the length of the profile. Choose Profile from the Window menu. Choose Show balance levels from the Profile menu. A tick will appear beside this item when it is selected. HighRoad will calculate the level which will produce close to a balance of cut and fill for each cross section. The maximum deviation of cut and fill will be no more than 5% and in most cases, the level calculated will produce a balance to within 1%.

 

Figure 14-6

When you first select the item there will be a delay while the levels are calculated (the watch cursor will appear on the screen). HighRoad will recalculate the balance levels whenever you change the typical section data. Each time HighRoad recalculates the levels the watch cursor will appear. Design the gradeline for the road as usual using the balance levels as a guide. You can specify a compaction or bulking factor to be used when calculating earthworks balance levels. (For further information see page 14-3, Compaction or bulking factor.)

 

Full bench construction

In rugged terrain it is often a design objective to have the road fully in cut, rather than having a balance of cut and fill. This is called full bench construction and HighRoad will calculate levels at which there is no fill, and display these levels on the profile as a square marker. This works in a similar manner to balance levels above. This is done by progressively lowering the cross section until no fill is present. This is approximate only but gives a good guide for a first trial gradeline. To use this option, choose Full Bench Levels from the Profile menu.

 

Mass haul diagram

This feature is used as an aid to minimising construction costs. The mass haul diagram shows the cumulative fill volume plotted against chainage along the road. The compaction (or bulking) factor is used in calculating the cumulative fill volume. Fill volumes are shown above the x-axis and cut volumes are shown below. The mass haul diagram is plotted between the quantities limits that you have chosen. A typical mass haul diagram is shown in Figure 14-7.

 

Viewing the mass haul diagram

First choose Quantities from the Window menu, then set the quantities limits by Limits... from the Quantities menu. Check the compaction factor by choosing Compaction Factor... from the Quantities menu. Choose Mass Haul Diagram from the Window menu. The earthworks quantities will be calculated and the mass haul diagram plotted between the quantities limits.

Figure 14-7

 

Change the horizontal scale of the mass haul diagram by choosing the appropriate scale from the View menu. You can make arbitrary adjustments to the vertical scale by using the vertical scroll bar. As the scroll box is moved towards the bottom of the window, the vertical scale is reduced. The mass haul diagram uses the same horizontal scale and horizontal scroll bar position as the Profile window. If both windows are visible the contents of both windows will change together as you scroll and change scales. If you adjust the finished surface profile, the mass diagram will be recalculated and redrawn to suit.

 

Printing the mass haul diagram

When the Mass Haul Diagram window is the front window you can print the diagram. Choose Print Mass Diagram... from the File menu. The diagram will be printed with the horizontal axis centred on the page.

 

Using the mass haul diagram

The mass haul diagram provides an indication of the haul distances involved in a particular job. With roads of substantial length it may not be sufficient to simply achieve a balance of cut and fill volumes. It is also important to ensure that haul distances are minimised. The cut and fill volumes are balanced between points where the diagram crosses the x-axis. In general, the more often the plot crosses the x-axis, the lower the haul distances. You can examine the mass haul diagram, adjust the design profile or typical sections, then review the total quantities and mass haul diagram to see the effects of these design changes.

 

Volume to a datum

Cut and/or fill volume between the terrain surface and a datum, and within a defined area can be calculated. To define the area within which the calculations are to be made use a special feature string called Volume boundary. This feature must be joined, and closed, and contourable.

 

Non-contourable or non-breakline features

To calculate volumes HighRoad calculates the volume of each triangle. Therefore the earthworks boundary must be made up of triangle sides. If the feature is on non-contourable points, or is not a breakline it will probably cross over triangle sides. To calculate volumes for such a feature HighRoad will have to adjust the triangles to match the volume boundary. In the case of a non-contourable feature, HighRoad first has to make the boundary vertex points contourable. This has to be done without changing the shape of the terrain so the vertex points have to be set at ground level. HighRoad calculates the ground level at the vertex location, sets the elevation of the vertex to ground level, then makes the point contourable and incorporates it into the triangulation.

For non-breakline features, new points have to be created wherever the feature line intersects a triangle edge. These points are also given an elevation equal to the ground level at this point to ensure that the shape of the terrain is not changed by this process.

After both these steps are done, the earthworks boundary now lies along triangle edges and the volumes can now be calculated.

Warning: Because the triangulation may be adjusted to meet these requirements you should save your project as another name before doing volume calculations. You can then always go back to the earlier version with the original triangulation.

Calculating volumes

The calculations are done and listed in the Text window. To begin you must make a new feature and mark it as a volume boundary feature. (You can also change an existing feature to be used as an volume boundary). Choose New feature string... from the Plan menu. A dialog box as shown in Figure 4-10 will appear. Select Volume boundary from the pop-up menu in the feature dialog box and create the new feature.

Switch to the Text window, select Datum plane for volumes... from the Text menu and set the volume datum. You can change the size of the Text window so it is small and the Plan window is visible behind it. In this way, as the calculations are done the triangles that were used for the calculations will be visible on the Plan view. Choose Volume to plane calculations from the Text menu. The volumes will be calculated and listed in the Text window.

You can create more than one volume feature in each project. Each volume feature used in the calculations will be listed.

Warning: There are some limitations to this simple method of earthworks calculations. The volume of each triangle is calculated by using its average height. This will produce an incorrect result if the datum level is not completely above or completely below all points within the earthworks boundary. In the case of a triangle with points both above and below the datum, its volume will be calculated as the net cut or fill for that triangle. For example if its volume is made up of 12 m3 of fill and 5 m3 of cut, it would be listed as 7 m3 of fill. Triangles completely above or below the datum will be calculated correctly.

 

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