Alignment
by Parallel Offset(This functionality is available with the Computations
module)
Creates a new alignment and associated points parallel to a nominated existing alignment.
To run this option, first ensure that the Utilities/Configure/Units command is set to grid distances. Then select the Create/Alignment command and the Method/Parallel command from the Computations task to display the relevant dialog box.
The alignment to be created will be given the attributes currently defined via the Attributes/Alignment command. The lines to be created will be given the attributes currently defined via the Attributes/Line command, and the associated points created will be given the attributes currently defined via the Attributes/Point command.
Note that any spiral objects in the initial alignment will become splines in the parallel alignment being generated. By default, any spline created parallel to a spiral will contain new points and be based on points computed at every 5° change of spiral angle. The minimum number of points used is 5 (2 end points and 3 internal). This ensures a smooth spiral without unnecessary points being created.
The frequency of additional created spiral points may be controlled via the registry setting:
HKEY_CURRENT_USER\Software\LISTECH\LISCAD\10.x\SEE\General Settings\Alignment\SpiralCreation
The default registry setting is created the first time a spline is created parallel to a spiral. The default setting is as follows, where 0.087266 is simply 5 degrees expressed in radians.
SpiralCreation REG_SZ 0.087266, 4
Create Parallel Alignment dialog box
| Item | Used to |
| Alignment | Select the alignment from which the parallel alignment will be generated. |
| Offset | Key in or specify the offset
(i.e. distance) which is to be measured in a perpendicular direction
from the existing alignment to the new alignment being created. A negative offset will be applied to the left of the existing alignment, whereas a positive offset will be applied to the right. |
| or | |
| Point ID: | Select an existing point such that the offset to the new alignment will be the offset from the existing alignment to the point selected. |
| Elevation Group Box | Select how the elevations of the parallel alignment are to be calculated. |
| No Elevation | Specify that the parallel alignment will not have elevations. |
| or | |
| Fixed Elevation | Specify that the parallel alignment will have a fixed elevation entered in the Elevation field. |
| or | |
| Height Difference | Specify that the parallel alignment will have elevations at a height difference to the existing alignment entered in the Elevation Difference field. |
| or | |
| Grade | Specify that the parallel alignment will have elevations at a height
difference to the existing alignment specified by the Grade field.
The grade is entered as a percentage or ratio as set in the Utilities/Configure/Units command. The grade refers to the grade along the offset from the existing alignment to the parallel alignment. |
| or | |
| Alignment | Select an alignment against which elevations will be extrapolate/interpolated. |
| Trim New Alignment | Select this check box if you wish the new alignment(s) to be trimmed to remove any areas where they cross themselves, and lie within the required offset from the original alignment. |
| OK | Create the parallel alignment. |