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Shoulder Design in MX v8i


Prerequisites

Before shoulders can be designed, the roadway strings must exist and the superelevation applied.

Creating the Shoulder

Before starting the wizard, it may be advisable to open a journal file to capture the MX commands used to create the shoulder design.  This journal file (with some editing) can be run to reproduce the design when necessary without having to use the wizard again.

Create a display with centerline and pavement edges.  Start the shoulder design wizard: Design => Road Design => Shoulder Design...

                        Shoulder Reference Details panel

From the Reference Details panel, enter the Design Model, Reference String and Edge of Pavement data as shown above.  Click Next to advance to the Standard Methods panel.

                       Shoulder Standard Methods panel

For the Standard Shoulder Method, select the Fixed Cross Slope method.  For the Shoulder Method for Curves, check the box for Define Method for Outside of Curve and Define Method for Inside of Curve.  Click Next to advance to the Standard Methods - Fixed Cross Slope panel.

Fixed Cross Slope panel

Define shoulder width and cross slope.  Click Next to advance to the Outside Methods panel.

Shoulder Outside Methods panel

Choose the Shoulder Roll-over option.  None of the options available reproduce NHDOT practices exactly, this is the closest one.  Click Next to advance to the Outside Method - Shoulder Roll-over panel.

Roll-over Superelevation Details tab

Specify the Maximum Shoulder Break which is allowed before the new cross slope values are implemented.  Ideally, the high-side shoulder would reach it's ultimate 2% cross slope when the traveled way is at it's reverse crown point.  However, it appears that this wizard completes the transition at the beginning of full bank point.

Therefore, enter the value of 0.03 (3.0%) as the Maximum Shoulder Break.  In a normal crown section, there is typically a 3% difference between the traveled way and shoulder (from 2% to 5%).  By setting this value at 0.03 (3.0%), MX will begin modifying the shoulder superelevation as soon as the traveled way starts rotating up.

Roll-over Details tab

On the Shoulder Roll-over Details tab, enter the distance between the TW and shoulder crown, maximum cross-slope of the inner half (usually 0.02), and cross-slope of the outer half (usually 0.05). Make sure the up/down arrow is pointed in the correct direction.  The illustration will change to reflect the directions.  Click Next to advance to the Inside Design Method panel.

Shoulder Inside Method panel

For the inside of the curve, select the Follow Roadway Cross Slope option.  Click Next to advance to the Start and End Points panel. 

Start and End panel

Select the start and end stations for the current shoulder application segment.  Select Next to work on the other side of the road or to define another segment on the same side of the roadway.  All the previously selected options will default to the previously chosen values.

Create Another Length panel

Select Finish to exit the Shoulder Design wizard.


Related Pages

Shoulder Design in MX-Uncurbed

Shoulder Design Journal Files

 





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