OverlayMillAndLevel2

Attachment

The attachment point is the crown point on the overlay finish grade.

Input Parameters

Note: All dimensions are in meters or feet unless otherwise noted. All slopes are in run-over-rise form (for example, 4 : 1) unless indicated as a percent slope with a “%” sign.

Parameter	Description	Type	Default
Crown Point Offset	Offset of the crown point. The crown and sample points are used to calculate the left and right slopes of the existing roadway.	Numeric	0.0
Left Sample Point Offset	Offset of the left sample point	Numeric	0.0
Right Sample Point Offset	Offset of the right sample point	Numeric	0.0
Left Trim Point	Offset of the left trim point, which defines the outside edge of the overlay layer on the left side	Numeric	0.0
Right Trim Point	Offset of the right trim point, which defines the outside edge of the overlay layer on the right side	Numeric	0.0
Left Overlay Slope Options	Specifies the left overlay slope with the following options: a) user defined, b) to match slope from inside sample point to outside sample point or, c) use the outside lane superelevation slope of the baseline alignment.	Selection list	Match slope
Default Left Overlay Slope	Specifies user defined slope. Also can be used if match points or superelevation slope doesn’t return appropriate value.	Numeric, grade	- 2.0 %
Right Overlay Slope Options	Specifies the right overlay slope with the following options: a) user defined, b) to match slope from inside sample point to outside sample point or, c) use the outside lane superelevation slope of the baseline alignment.	Selection list	Match slope
Default Right Overlay Slope	Specifies user defined slope. Also can be used if match points or superelevation slope doesn’t return appropriate value.	Numeric, grade	- 2.0 %
%Slope Tolerance	The value that the Overlay Slopes are allowed vary from their design values. The slope tolerance is not used if the Overlay Slope is given as M (see Behavior below for details).	Numeric, positive	0.5%
Use Profile	Selects whether to hold the top of overlay at the inside trim point to the corridor profile elevation, or to set the vertical placement of the overlay layer based on the Minimum Clearance value	Selection List	Use minimum clearance
Minimum Clearance (+/-)	The minimum vertical clearance between the existing surface and the bottom of the overlay layer. A positive value places the bottom-of-overlay link above the existing surface, creating a Leveling layer beneath the overlay. A negative value places the bottom-of-overlay link below the existing surface, creating a Milling layer that coincides with a portion of the Overlay layer.	Numeric	0.100 m 0.30 ft
Overlay Depth	The thickness of the overlay layer	Numeric, positive	0.100 m 0.30 ft

Target Parameters

This section lists the parameters in this subassembly that can be mapped to one or more target objects, such as a surface, alignment, or profile object in a drawing. For more information, see To Specify Corridor Targets.

Parameter	Description	Status
Existing Surface	Name of the Surface defining the existing roadway. The following object types can be used as targets for specifying this surface: surfaces.	Required
Crown Point Offset	May be used to override the fixed Crown Point Offset and tie the point to an offset alignment. The following object types can be used as targets for specifying this offset: alignments, polylines, feature lines, or survey figures.	Optional
Left Sample Point Offset	May be used to override the fixed Left Sample Point Offset and tie the point to an offset alignment. The following object types can be used as targets for specifying this offset: alignments, polylines, feature lines, or survey figures.	Optional
Right Sample Point Offset	May be used to override the fixed Right Sample Point Offset and tie the point to an offset alignment. The following object types can be used as targets for specifying this offset: alignments, polylines, feature lines, or survey figures.	Optional
Left Trim Point Offset	May be used to override the fixed Left Trim Point Offset and tie the point to an offset alignment. The following object types can be used as targets for specifying this offset: alignments, polylines, feature lines, or survey figures.	Optional
Right Trim Point Offset	May be used to override the fixed Right Trim Point Offset and tie the point to an offset alignment. The following object types can be used as targets for specifying this offset: alignments, polylines, feature lines, or survey figures.	Optional

Output Parameters

Parameter	Description	Type
Superelevation Axis of Rotation	Indicates whether the subassembly supports the axis of rotation calculation. To view a description of the parameter, in the Properties window, hover the cursor over the parameter. For more information, see Profile Grade Line Adjustments During Superelevation.	Static (Description)
Left Overlay %Slope	The slope used for applying the overlay layer on the left side	Numeric
Right Overlay %Slope	The slope used for applying the overlay layer on the right side	Numeric

Parameter

Description

Type

Superelevation Axis of Rotation

Indicates whether the subassembly supports the axis of rotation calculation. To view a description of the parameter, in the Properties window, hover the cursor over the parameter.

For more information, see Profile Grade Line Adjustments During Superelevation.

Static (Description)

Left Overlay %Slope

The slope used for applying the overlay layer on the left side

Numeric

Right Overlay %Slope

The slope used for applying the overlay layer on the right side

Numeric

Behavior

This subassembly inserts parallel links defining the top and bottom of an overlay layer on each side that join at the crown point. The links are inserted from the Crown Point Offset to the Left and Right Trim Offsets.

Overlay Slopes

The slope of the Existing Surface on each side is determined betweenthe crown and sample points. The slopes of the overlay layers aredetermined by the following steps:

If the Overlay %Slope input is given as M, then the overlay slope matches the slope from the Crown Point to the Sample point.
If the Overlay %Slope is given as S, then the overlay uses the outside lane superelevation slope defined for the corridor alignment.
If a numeric value is given for the Overlay %Slope, the given value is used.
If a numeric value or the superelevation slope is used, the overlay slope is compared to the existing slope between the sample points. If the difference exceeds the Slope Tolerance value, the design slope is adjusted up or down by the Tolerance value to make it more closely match the existing slope and minimize the amount of leveling or milling. Slope adjustment does not occur if the Slope Tolerance is zero.

Overlay Elevations

The elevations of the overlay points are determined as follows:

If the Use Profile value is True, the elevation of the corridor profile is held at the Crown Point offset on the top of overlay. The overlay is extended to each side at the overlay slopes to the Left and Right Trim offsets, and parallel links are inserted for the bottom-of-overlay. Any areas above the existing surface and below the bottom-of-overlay are stored as closed shapes with code “Level”. Areas below the existing surface and above the bottom-of-overlay are stored as closed shapes with code “Mill”.
If the Use Profile value is False, the bottom-of-overlay link on each side is shifted vertically to hold to the Minimum Clearance above or below the existing surface. A positive Minimum Clearance creates a leveling area above the existing surface and below the bottom-of-overlay. A negative clearance creates a milling area below the existing surface and above the bottom-of-overlay. The overlay links on one side are shifted vertically so that the links meet at the crown point.

Minimum Clearance Point

The method of determining the point where the Minimum Clearance applies is shown in the diagram below.

A vertical projection line is established at any arbitrary offset.
Each point on the Existing Surface between the two trim points is projected back to the projection line at the Overlay Slope.
The point with the highest elevation on the projection line is the control point for a Minimum Clearance value greater than zero. The one with the lowest is the control point for a Minimum Clearance value less than zero.

Layout Mode Operation

In layout mode, this subassembly displays the overlay layer positioned from any convenient point of attachment at a slope of -2%.

Point, Link, and Shape Codes

The following table lists the point, link, and shape codes for this subassembly that have codes assigned to them. Point, link, or shape codes for this subassembly that do not have codes assigned are not included in this table.

Point, Link, or Shape	Code	Description
P1	Crown	Crown on finish grade
P2, P3	EOV	Overlay edges on finish grade
P4	Crown_Overlay	Crown on bottom-of-overlay
P5, P6	EOV_Overlay	Edges of bottom-of-overlay
L1, L2	Top, Pave	Top of overlay
L3 – L6	Overlay	Overlay links. Note that L5, L6 go from the bottom-of-overlay to top-of-overlay in both the Leveling and Milling cases.
L7, L8	Level Mill	Verticals from existing surface to bottom-of-overlay: Level - For the Leveling case. Mill - For the Milling case.
S1	Overlay	Area between the top and bottom of overlay. This overlaps the milling area (S3) for the Milling case as shown below.
S2	Level	Area above existing surface and below the bottom of overlay (Leveling case)
S3	Mill	Area below the existing surface and above the bottom of overlay (Milling case). This area overlaps the Overlay area as shown below.