|Creative Engineering home page|

|Table of contents | Learning HighRoad | Using HighRoad| Reference|

| Previous | Next |

Chapter 5 Road alignment

 

This chapter shows you how to design the horizontal alignment of a road. You can add up to 100 control lines in any project. if you are using HighRoad Plus, HighRoad Pro or have purchased the license to use the Extra control lines module.

Laying out the horizontal alignment

The horizontal alignment is entered on the terrain model (in the Plan window) using the mouse. Choose an appropriate scale from the View menu so that you can begin to lay out the horizontal alignment. For information about plan transition curves (spirals) see Chapter 9, Transitions.

Choose New control line... from the Plan menu. A dialog box (see Figure 5-1) will appear. Name the control line and click OK. The name will appear in the Active menu.

 

Figure 5-1

 

You can now enter the horizontal alignment for that control line. Choose New IP from the Plan menu. The cursor will change to a cross when it is over the Plan window. Hold the mouse button down and drag until the horizontal intersection point (IP) is in the desired position. A small circle () will be drawn here to represent the IP. For each new horizontal IP, choose New IP and position in the same manner. A line will be drawn to the previous IP with a curve inserted for the previous IP.

Note: If the deflection angle at an IP is less than 0° 15'00", HighRoad will not insert a curve. The radius will be set to zero, indicating that no curve is to be used. If the radius is set to zero and locked, no curve will be inserted no matter what the deflection angle. This option may be useful if you wish to use HighRoad to create drainage or sewerage longitudinal sections. If you choose a curve radius larger than will fit between the adjacent curves, a warning will be displayed, and the radius set to the maximum that can fit without overlapping the next or previous curves. These parameters are set in the dialog box as shown in Figure 5-2. Double-click on the IP when the cursor is a four pointed arrow () to see the dialog box.

 

Continue until you have entered all the horizontal IPs for the road. The control line can temporarily run off the edge of the model while you are selecting the correct alignment. Once the horizontal alignment is in place, you can view the profile along this alignment and design the typical section and gradeline.

Note: You cannot display the profile, cross sections or the full plan view if the control line runs off the edge. You should not attempt to display any other view other than the plan of the control line, if the control line runs off the edge of the terrain model.

Editing the horizontal alignment

You can change the position of any of the horizontal IPs. Move the pointer to the IP you want to adjust and it will change to a four pointed arrow (). Drag the arrow to the new location. HighRoad will redraw the new view of the plan. You can also precisely specify the location of the IP and the details of the curve data. Double-click on the IP when the cursor is a four pointed arrow (). The dialog box shown in Figure 5-2 will appear on the screen.

 

Figure 5-2

Change the position of the IP or the elements of the curve using the usual editing techniques. Click Calculate Now to show the effect of any change on the other curve data. If you make a change and then move to another field, the curve data will be recalculated. Click Previous and Next to view the previous or next intersection point along the alignment.

Note: Do not drag any horizontal IP outside the terrain model, or locate it so that the control line crosses outside the terrain model. If the first or last IP is dragged off the edge of the terrain model, HighRoad beeps as a warning and returns the IP to its original position. IPs other than the first or last points can correctly be off the model. You can drag the control line off the edge of the terrain model while you are adjusting the horizontal alignment. As the alignment of the control line is refined it should be moved within the terrain. It is necessary for the control line to be within the terrain model when you display a profile or cross sections, or any other window which depends on calculation of natural surface along the control line or along a cross section. If you try to open one of these windows while the control line is not entirely within the terrain model a warning will be displayed and the window will be closed.

You can also insert and delete horizontal IPs. Insert IP... and Delete IP... are available in the Plan menu when two or more IPs have already been added. To insert an IP into an alignment which has already been laid out, find the number of the IP (by double-clicking on it) after which you wish to insert an extra IP. Choose Insert IP... and a dialog box which asks for this number will appear. The extra IP will be inserted half way between the IP you nominated and the next IP. You can then drag it to its correct location, or relocate it by double-clicking it and editing the values shown in the dialog box.

To delete an IP, choose Delete IP... The cursor will change to an X shape. Position the cursor over the IP to be deleted and click. The IP will be deleted. Choose New IP to add an extra IP to the end of the horizontal alignment.

You can select what information HighRoad will display about the control line in the Plan view. Select Show <Control line name> details... from the Plan menu. A dialog box with the name of the control line, as shown in Figure 5-3, will appear. You can choose to show no details, control line only or the whole road.

Note: Details about the road will only be shown in the Plan view when you have designed a typical section and gradeline for the road.

The transparent road option and the batter rill symbols are only available when All is selected. If All is selected and the control line runs off the edge of the road only the control line will be shown. Transition chainages will not be shown unless superelevation or plan transitions have been calculated. (See Chapter 8, Transitions, page 9-1.)

Figure 5-3

 

Redrawing the plan

Redrawing the plan view of the road after scrolling may take some time. The speed of drawing is influenced by the size of the straight segments which are drawn to represent curved lines. With long segments, the speed of drawing is faster but the drawing appears as a series of straights rather than as a smooth curve. You can change the segment length by typing in the required distance between cross sections in pixels. Selection of a larger distance between cross sections (for example, 40 pixels) will speed up the redraw considerably but may not be suitable for detailed work or when printing.

You can also choose not to display any mark at all for points. This means that you do not have to wait for the dots to be drawn for points. This speeds up redraw noticeably on slower computers. In combination with redraw interruption (as discussed below) this can speed up your work considerably.

HighRoad allows you to choose whether plan redrawing will be stopped when the mouse is clicked. Select Preferences... from the Edit menu. Check the box labelled Stop plan redraw on mouse click. This setting will be remembered by HighRoad. Once selected, plan redraw is stopped when the mouse is clicked. This is useful if you are zooming in on part of the plan. You may need to zoom in several times to get to the scale that you want. Instead of waiting for the plan to fully redraw each time, you can wait just long enough to see sufficient detail to know where you are, then choose Zoom again. As you click on the View menu the plan drawing will stop, allowing you to select Zoom again. (This also applies if you are using the Command () key on Macintosh or the Alt () key on Windows to zoom.) Be aware that the plan view may be incomplete if the mouse button is down at any time during plan redraw.

Plan drawing does not stop under all conditions. The first time contours are drawn they also have to calculated. This cannot be interrupted. Subsequent redraws are much faster (providing sufficient memory was available to store the contours) and can be interrupted by a mouse click. You can also force an update of the plan view. If you interrupt the drawing of the plan view, you may be left with a partly completed plan. To force the Plan window to be redrawn, click on the size box in the lower right corner. The Plan window will be redrawn completely.

 

Multiple control lines

Note: This option is available only if you are using HighRoad Plus, HighRoad Pro or have purchased the license to use the Extra control lines module.

You can add up to 100 control lines in any project. Simply select New control line... from the Plan menu. A dialog box (as shown in Figure 5-1) which allows you to name the control line, will appear. Each time you add another control line its name will also appear in the Active menu. The current control line (the one on which you are working) has a tick against it in the Active menu and all views of the road (Plan, Profile, Cross Section etc.) show information relating to that control line. The background of the current control line is displayed in yellow. The details displayed about each control line in the Plan view will depend on what you have selected for that control line. Choose Show <Control line name> details... from the Plan menu. A dialog box with the name of the control line, as shown in Figure 5-3, will appear.

Choose the details to be shown for that control line. Remember that details about the control line will only be shown in the Plan window when you have designed a typical section and gradeline for the control line.

Note: At present no account is taken of overlapping control lines when calculating quantities or batter slopes unless all control lines which intersect the current one have been constructed. See Constructing the road, page 4-18.

Locating a point on a control line

You can easily calculate the location of a point along the current control line given its chainage and offset and the bearing and distance to a reference point. Choose Location on control line... from the Plan menu and a dialog box as shown in Figure 5-4 will be presented. Enter the chainage and offset of the location required and the northing and easting of the reference point if required.

Figure 5-4

The northing, easting and the bearing at the control line and the bearing and distance to the reference point will be displayed after you click Calculate Now (or move to another field by tabbing or by clicking in the other field).

If you type a chainage which falls outside the limits of the design information for this control line, the chainage will be adjusted to the nearest location actually within the design information. Likewise, enter the chainage and offset of the location required and its northing, easting and the bearing at the control line will be displayed after you click Calculate Now or move to another field by tabbing or by clicking in the other field.

 

| Previous | Next |