OverlayBrokenBackBetweenEdges

This subassembly is used to overlay a four-lane crowned corridor between gutter flange points on each side, holding to required slope and breakover ranges. This subassembly differs from OverlayBrokenBackOverGutter because it overlays between known flange points, rather than overlaying existing gutter to a known profile on the face of curb.

To use this subassembly, you should have separate alignments defining the left and right edges. Elevations at these points could come from surfaces or profiles. Furthermore, if the component defining the edges (for example, curb and gutter) is also a rehab component, then they could be passed in as marked points, thus transferring offset and elevation information.

Attachment

The attachment point is (near) the crown point of the subassembly. This is typically at the assembly baseline point. While in layout mode, this point coincides with crown point, in the corridor state the finshed grade profile point (or baseline marker point) may not be same as crown point, since its offset and elevation are computed by edge of pavement data.

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
Left Flange Offset	Distance between default attachment point to left edge of pavement. This value is used only if no alignment or marked point is associated to left edge.	Numeric	- 18ft
Right Flange Offset	Distance between default attachment point to right edge of pavement. This value is used only if no alignment or marked point is associated to right edge.	Numeric	6m and 18ft
Left Flange – Marked Point	Provides existing left edge of pavement offset and elevation to start the subassembly. (OPTIONAL)	String	None
Right Flange – Marked Point	Provides existing right edge of pavement offset and elevation to start the subassembly. (OPTIONAL)	String	None
Minimum Overlay	Minimum depth of overlay at the quarter points and crown.	Numeric	0.1m and 0.33ft
Inside Min %Slope	Minimum % slope allowed for the inside lanes, in the outward direction from the attachment point.	Numeric	-1%
Inside Max %Slope	Maximum % slope allowed for the inside lanes, in the outward direction from the attachment point.	Numeric	-4%
Outside Min %Slope	Minimum % slope allowed for the outside lanes, in the outward direction from the attachment point.	Numeric	-2%
Outside Max %Slope	Maximum % slope allowed for the outside lanes, in the outward direction from the attachment point.	Numeric	-6%
Max Breakover	Maximum breakover, in % slope, at the centerline.	Numeric	4%
Min Crown Deflections	Minimum crown deflection at the quarter points.	Numeric	0.05m and 0.16ft

Note that if target parameters are provided, the preceding parameters (namely default offsets and marked points) will be ignored as applicable.

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
Left Flange Point	Provides left edge of pavement offset value with respect to the attachment point. The following object types can be used as targets for specifying this: alignments, polylines, feature lines, or survey figures.	Optional
Right Flange Point	Provides right edge of pavement offset value with respect to the attachment point. The following object types can be used as targets for specifying this: alignments, polylines, feature lines, or survey figures.	Optional
Left Flange Profile	Provides left edge of pavement elevation value with respect to the attachment point. The following object types can be used as targets for specifying this: profiles, 3D polylines, feature lines, or survey figures.	Optional
Right Flange Profile	Provides right edge of pavement elevation value with respect to the attachment point. The following object types can be used as targets for specifying this: profiles, 3D polylines, feature lines, or survey figures.	Optional
EGTopSurf	If profiles are not supplied for left/right edge of pavement elevations, then this surface elevation at that offset will be picked up as elevation value (for left/right) respectively. The following object types can be used as targets for specifying this surface: surfaces.	Required

Output Parameters

Parameter	Description	Type
Left Outside Lane %Slope	% slope of the left outside lane	Numeric
Left Inside Lane %Slope	% slope of the left inside lane	Numeric
Right Outside Lane %Slope	% slope of the right outside lane	Numeric
Right Inside Lane %Slope	% slope of the right inside lane	Numeric

Behavior

This subassembly uses an iterative process to develop acceptable slopes of the inside and outside links. The initial slopes are set as described below. Each time the slope of one link is adjusted, resulting changes in the adjacent links may put them out of design tolerances. If a solution is not obtained within 10 iterations, a message is displayed and the process is aborted.

Left Edge of Pavement

From the attachment point, the left edge of the pavement point is located based on: (a) the location of the alignment through the "Left Flange Point" target parameter, (b) if this is not provided, it is based on the assigned marked point (to Left Flange Point), or (c) if both of these are not provided, then it is based on the default (Left Flange Offset) offset value.

Similarly, the elevation for this point is computed based on: (a) the Left Flange profile target parameter, (b) if this is not provided, then the surface elevation is determined from the "EGTopSurf" Logical assignment , or (c) if both of these are not provided, then the assigned marked point determines the elevation. An error message results if none of these two conditions are met and the corridor fails to build.

Right Edge of Pavement

From the attachment point, the right edge of pavement point is located based on: (a) location of alignment through "Right Flange Point" target parameters, (b) if previous is not provided, based on the assigned marked point (to Right Flange Point), or (c) if both are not provided based on the default (Right Flange Offset) offset value.

Similarly, elevation for this point is computed based on: (a) Right Flange profile target parameters assignment, or (b) if previous is not provided then finding out the surface elevation from "EGTopSurf" Logical assignment, or (c) if the previous two are not provided, the assigned marked point determines the elevation. An error message results if none of these two conditions are met and the corridor fails to build.

Crown Point

The Crown Point (offset) is located at halfway between the left edge and right edge of pavements.

Elevation of the crown point is the sum of "average elevation of left and right edges" and the "crown height" parameter value.

Bottom of Overlay

Bottom of overlay surface is computed by offsetting the proposed finish grade (Left Edge point to New Crown Point to Right Edge Point) by Overlay depth value.

Quarter Points and Crown Point Offsets

The distance between left and right flange points is divided by four to get the two quarter points and the crown point. These points elevations are computed by adding the minimum overlay depth to the existing ground at these offsets.

Inside and Outside Pavement Slopes

The resulting overlay links from the previous steps are checked for being within the slope tolerances for the outside and inside lanes. If the slopes are within the tolerence, then the case is a simple overlay as shown in the following diagram.

If overlay links are too steep, or if the Maximum Breakover is exceeded at the centerline, or the Min Crown Deflection is not obtained, some or all links are flattened to their maximum slopes. Milling surfaces are inserted to hold the minimum overlay depths at the quarter points and centerline.

If overlay links are too shallow, the depth of overlay is increased to achieve the minimum slopes. If this results in too much breakover, further adjustments and milling may occur. The following diagram explains overlay with milling case:

Special Cases

A positive slope may be allowed on one inside link if the other inside link has a negative slope, as shown below.

Layout Mode Operation

In layout mode, this subassembly inserts two lanes at either side of the attachment point. First two edge points will be located based on left/right offsets. These left and right point elevations are calculated (in layout mode) by subtracting crown height from the ordinate of attachment point. Then the "Crown Point" is located halfway between these two points. However, since the programatic defaults are the same for both left and right, by default the crown point matches with attachment point. Lane slopes in layout mode are equal to the "Min % Outside/Inside Slope" value. Thickness of pavement is equal to Minimum Overlay depth.

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, P5	ETW	Edges of lane on finish grade
P6, P10	ETW_Overlay	Edges of lane on Overlay
P3	Crown	Crown (grade break) on finish grade
P8	Crown_Overlay	Crown (grade break) on Overlay
P2. P4	LaneBreak	Grade break point at quarter points
P7, P9	LaneBreak_Overlay	Grade break point at quarter points on overlay surface
L1, L2, L3, L4	Top, Pave	Finish grade surface
L5, L6, L7, L8	Overlay	Overlay surface
S1	Overlay	Overlay area