3D-MC: How to create a crown road surface

Creating a Crown road surface is similar to creating a sloping surface with the addition of defining the length and width of the crown road surface.

Creating a Crown Road Surface is a simple process.  The operator will need to enter four elements for the crown road surface.

• Starting Point: Will set the elevations of the surface as it did when creating a Flat/Sloping Plane Surface.  The elevation is typically set after the surface has been defined.
• Main-fall: Will define the direction of orientation of the Centerline and set the slope Grade of the centerline.  This step is typically done first.
• Cross-fall from crown: Will define the cross slope left and right of the centerline.
• Width of road: Defines the overall width of the road.

Setting the Centerline can be achieved a few different ways.

• Direction/Grade: If a GPS heading of the centerline is known the operator can enter the heading value in the Direction Box and set the grade at the defined heading.
• Length: Will define the total length of the centerline.  The begining of the centerline will start at the A point and end at the B point.  To continue the centerline further beyond point, enter the desired length from point A.  This will continue the centerline beyond the B point.

Setting the Main Slope of the Centerline can be achieved a few different ways.

• If the operator has a set of points for the centerline in the points file they can select the points using the select point button.
• When using the select point option the Direction/Grade will be set from the elevations of the points.
• The Direction and Grade can be edited by simply selecting either the Direction or Grade and changing the values.
• A positive or negative slope is determined by defining the direction of the points selected.  From A to B a slope heading uphill is positive.

Setting the Main Slope of the centerline can be achieved a few different ways.

• The operator can use the A/B buttons to take survey shots using the machine to set the Direction and Grade of the centerline.
• Survey Shots will be taken from the last point of steering the machine used.

The operator can set the proper elevation by either

• Selecting a point from the points file which has the correct elevation.
• Taking a topo shot on a known elevation.

Once the Crown Surface has been defined any of the values can be changed, if required.

The surface that was created was a ditch 100' long and 50' wide with 2% slope flowing along the centerline.