1.1.4.1 Horizontal Segments

Each Alignment object must contain one or more of the following objects to define the horizontal control line. Multiple of these segments can be stacked up in order to define the full horizontal alignment.

Object Types for Horizontal Segments

1. Straight

T="Straight"

Used to define straight segments on horizontal alignment. This can only be placed inside an Alignment Object.

Parameters for Straight object

2. Circular

T="Circular"

Used to define a circular curve portion on the horizontal alignment.

Parameters for Circular object

3. Spiral

T="Spiral"

Used to define transition segments on the horizontal alignment.

Parameters for Spiral object

Additional Parameter

The Spiral object by default uses clothoids for transitions. This is the most common transition curve in roadway geometry.

CurveType - This parameter will be added as the need for different type of transition curves arises (ex. railroad geometry).

Examples

Straight object

The following is an example of a 200 feet straight segment named ST1 -- name is optional.

<O N="ST1" T="Straight">

<P N="Length" V="200" />

</O>

Circular object

The following is an example of a circular curve length of 250 feet with radius 1200 feet. Looking up station along the alignment line, the curve goes towards the right side.

<O N="CR1" T="Circular">

<P N="Length" V="250" />

<P N="Radius" V="1200" />

<P N="Direction" V="RIGHT" T="Text" />

</O>

Spiral object

The following is an alignment definition with three horizontal segments, straight, followed by transition curve, followed by a circular curve.

<O N="HCL" T="Alignment">

<O N="TangentSeg_1" T="Straight">

<P N="Length" V="100" />

</O>

<O N="Spiral_Bk" T="Spiral">

<P N="Length" V="210" />

<P N="Direction" V="RIGHT" T="Text" />

</O>

<O N="Curve_101" T="Circular">

<P N="Length" V="300" />

<P N="Radius" V="200" />

<P N="Direction" V="RIGHT" T="Text" />

</O>

</O>