Texas DOT Superelevation - Update 6/27/2023

For high speed or non-urban facilities, this program calculates superelevation rates as shown in the Roadway Design Manual, Table 2-4 for emax = 6% and Table 2-5 for emax = 8%. These tables use Superelevation Distribution Method 5, per 2018 AASHTO Greenbook criteria. It also calculates superelevation rates for low speed urban facilities (emax = 4%) using Table 2-3 in the Roadway Design Manual per Superelevation Distribution Method 2.

Superelevation transition rates are automatically computed using the Maximum Relative Gradients and Multilane Adjustment Factors as shown respectively in the Roadway Design Manual, Table 2-6 and Table 2-7. The portion of superelevation transition located on the tangent is automatically calculated per Table 2-8.

Input variables:

Criteria - General input data to define the superelevation calculation.

Basis - Select Texas High Speed or Non-Urban or select Low Speed Urban Streets.

Design Speed (mph) - Once Basis has been selected, the Design Speed options will automatically be displayed.

e_max ('/') - The maximum superelevation is automatically selected when Basis is selected.

+/- Positive or negative slope of the curve. Generally used for transition calculations.

Description - Enter any description to be included in the printed output.

Geometry Data - Input data specific to the Curve and Transition.

Radius R - This is the Radius of the Curve (ft). Input this or Degree of Curve.

Degree D - This is the Degree of Curve (Decimal Degrees). Input this or Radius.

Trans Type - Select the Transition Type.

Reverse Parabola - The default, used where appearance is a factor. Adds continuous smoothing from the beginning to end of the transition.

Linear - Generally prefered for bridges, no transition smoothing.

Trans Length - Select Minimum for L_{CT(min)} or Desirable for L_{CT(des)}.

SE Calculations - This is where the Superelevation (SE) output information is displayed.

Action Bar

Run Button - Runs input data and calculates superelevations and transitions.

Clear All Button - Clears and resets the entire page.

Print Button - Prints the data calculated in the Texas DOT Superelevation program.

Close Button - Closes the Texas DOT Superelevation Superelevation program.

PC Transition - This is the input and output data for the transition at the PC of the curve.

Station - This is the PC station on the baseline. Do not enter a station plus.

e_back - This is superelevation back before the curve (normal crown or the prior curve). Sign +/- is important.

Width Rotated W - This is the distance between the axis of rotation and the edge of traveled way (ft).

Lanes Rotated n - This is the number of travel lanes rotated within the transition limits.

Tan Split% - Tangent Split is automatically set based on Table 2-8. Can be overridden. Do not add the binary "%" operator.

MRG G - Maximum Relative Gradient. This is automatically set based on Table 2-6. Can be overridden.

PC Transition output data is shown in the textbox below the PC Transition input data.

Specific Station Calculator - This calculates superelevations at stations within a superelevation transition.

Beg Sta - This is the Begin Station of the increment range. Do not enter a station plus.

Increment - This is the incremental distance between stations (ft).

Calc Button - calculates the superelevation at stations in the transition area.

Output - Station and superelevation output data is shown in the textbox below the input data.

PT Transition - This is the input and output data for the transition at the PT of the curve.

Station - This is the PT station on the baseline. Do not enter a station plus.

e_ahead - This is superelevation ahead after the curve (normal crown or the next curve). Sign +/- is important.

Width Rotated W - This is the distance between the axis of rotation and the edge of traveled way (ft).

Lanes Rotated n - This is the number of travel lanes rotated within the transition limits.

Tan Split% - Tangent Split is automatically set based on table 2-8. Can be overridden. Do not add the binary "%" operator.

MRG G - Maximum Relative Gradient. This is automatically set based on Table 2-6. Can be overridden.

PT Transition output data is shown in the textbox below the PT Transition input data.