Shoulder Design in MX v8i
Before shoulders can be designed, the roadway strings must exist and the superelevation applied.
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...
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.
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. Since the shoulder slope typically follows the roadway slope in a curbed area you may be tempted to choose the Follow Roadway Cross Slope method. However, doing this will not allow the option to select the shoulder roll-over option later. Click Next to advance to the Standard Methods - Fixed Cross Slope panel.
Define shoulder width and cross slope. Click Next to advance to the 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.
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 4% 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.
On the Shoulder Roll-over Details tab, enter the distance between the TW and shoulder crown, maximum cross-slope of the inner half (usually 0.04), and cross-slope of the outer half (usually 0.03). 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.
For the inside of the curve, select the Follow Roadway Cross Slope option. Click Next to advance to the Start and End Points 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.