Superelevation Preferences

The superelevation preferences are determined with guidance from the AASHTO Green Book and Federal Lands Highway standards and guidelines. Desired preferences are implemented by the Superelevation Preference menu shown below.  The menu is populated by an .sep (superelevation preference) file.  FLH has three (3) base .sep files used for each unit, English and Metric.
Seperelevation Preferences menu

Each preference file determines how the transitions in the roadway cross slope is accomplished, or superelevation transition, with many given factors and conditions.  The primary distinction of each method is how the superelevation transition is distributed with regard to the tangent (tangent runout) and the curve (Superelevation runoff).  The distribution method is expressed as a ratio of amount of transition in the tangent and amount of transition in the curve.  See Select Preference File on the Automated Superelevation menu for the preference file definitions and uses. See AASHTO Green Book, 3.3.8 Transition Design Controls, for detailed information.

The Menu

The following screen captures are all the tabs of the Superelevation Preferences menu and is for information only.  The preferences (.sep) files have been configured to FLH standards and guidelines.  THERE IS NO NEED TO ADJUST THESE SETTINGS.  When the menu was first created it was referred to as "The Monster" and when exploring the menu tabs and details, it is easy seen why it was nicknamed such.

The menu consists of 9 tabs:

The "e" Tab

Note the Table Name field should be automatically populated with english_2004_radiusTable_e.csv or metric_2004_radiusTable_e.csv.  This is done using the Directories command on the Automated Superelevation menu. This table defines the "e" rates with corresponding design speed and radii.  This tables controls the e Selection pulldown options of the Automated Superelevation menu.
Seperelevation Preferences menu, e Tab

Runoff Length Tab

Note the Table Name field should be automatically populated with fhwa_uscust_length.csv or fhwa_metric_length .csv.  This is done using the Directories command on the Automated Superelevation menu. This table defines the minimum length of transition with corresponding design speeds and relative gradient.  This tables controls the L Selection pulldown menu of the Automated Superelevation menu.
Seperelevation Preferences menu, Runoff Length Tab

Tangent Runout Tab

Seperelevation Preferences menu, Tagent Runout Tab

Adjust Factors Tab

Seperelevation Preferences menu, Adjust Factors Tab

Distribution Tab

Note the percentage shown On Tangent field will match the Superelevation preference file (.sep) name.
Seperelevation Preferences menu, Distribution Tab

Rotation Tab

Seperelevation Preferences menu, Rotation Tab

Reverse Curves Tab

Seperelevation Preferences menu, Reverse Curve Tab

Compound Curves Tab

Seperelevation Preferences menu, Compound Curves Tab

Short Curves Tab

Seperelevation Preferences menu, Short Curves Tab

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