Import LandXML Alignments

When importing LandXML alignments, Quantm supports independent combinations of entry and exit spirals of the following:

• Clothoid - (constant rate transition) - Select this to use a common clothoid spiral defined by the length of the spiral and the radius of the adjoining arc. This is a spiral whose curvature/radius either increases or decreases linearly along its length. Clothoid spirals transition from straight to arc at a constant rate of change (inverse of the radius). In alignments, clothoid spirals are used to gradually spiral into a circular curve (arc segment) from a straight segment and then back out of the curve to another straight or circular curve segment. This is a good spiral for highway and other low to medium speed alignments and where vehicles can be steered within the width of the lane to make up for a less gradual radius change.

• Cubic Spiral - Select this to use an approximation to the clothoid spiral (above) where y is the current offset from the tangent, l is the current length along the spiral, R is the radius at the end of the spiral, and L is the total length of the spiral.

• Cubic Parabola - Select this to use a cubic parabola defined by the length of the parabola and the radius of the adjoining arc.

• Bloss Curve

Quantm also supports independent entry and exit transition lengths when importing LandXML alignments. For alignments that have shorter or longer vertical alignments than the horizontal, Trimble recommends extending or clipping the vertical alignments to match the horizontal before importing. Quantm requires the vertical and horizontal alignments to be the same length to operate correctly. If an alignment is imported that has a shorter or longer vertical alignment it will be stretched or compressed to fit the horizontal alignment during import.

If you selected LandXML in the Import Alignment dialog:

1. Select OK when you have located the alignment file. The Cross Section Import dialog appears. The alignments in the file will appear in the Availablealignments tab.

2. Check the alignments you want to import.

3. Hit Next. In the Cross-sections tab, the available cross-sections appear.

4. Check the cross-section to import.

Next topic: Create Alignments