The vertical alignment is specified by a series of vertical point intersections forming longitudinal grades. A parameter to define the vertical curve links these grades. Vertical curvature is parabolic.
This option is not interactive, commands must be compiled in an MX Input File. An example VERAT input file is included at the end of this page for reference. The following describes VERAT.
VERAT has no exclusive minor options; instead it uses a series of records as follows:
Each VERAT data record contains associated data fields, these fields are delineated by commas. Comments and blank lines cannot be included within VERAT data.
Vertical curves may be defined by length, M value (default) or Radius (of the vertex). Length is the most commonly used option. The relationship between M value and the more commonly used K value is M = 100 / K where K = Curve Length / Algebraic Change in Grade. Code a positive M value (or R value) for sag vertical curves, a negative M value (or R value) for crest vertical curves.
Major Option Record
Major option VERAT has two associated model fields:
Initial Data Record*
*see Command Language Reference for greater detail.
Element Data Record, First point of intersection
End point of intersections do not define the extent of application, back tangents are extended or truncated to the limits described on the Initial Data record. There is only one first point of intersection.
Element Data Record, Intermediate points of intersection
*use either field 3 or 4. Curve length is the most commonly used option.
The data should be terminated by the global minor option 999.
All MX input files should begin with MOSS and end with FINISH.
New Hampshire Department of Transportation
PO Box 483 | 7 Hazen Drive |
Concord, NH | 03302-0483
Tel: 603.271.3734 | Fax: 603.271.3914