Imperfect Intersections

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Imperfect Intersections

We'll repeat the process for the last intersection with Alley 3 and Alley 4. Notice that because of

the transitioning geometry at the northwest curb return, the pavement edge is setback beyond the10' lane width value we have been using. This is not a problem because instead of configuring a

lane width of 10' for the primary road left offset parameters, we'll tie it to Road A's left offsetalignment created to generate the curb/gutter baselines. We will perform this for the Alley 3intersection. Alley 4 will be configured like the others.

So as we run through the intersection routine for Alley 3, we'll make this change to our processfor offset parameters:

Four-way Intersections with Three Alignments

We're defining each alley using the intersection tool. Before using the intersection tool, an

assembly set needs to be created. I determined that the following set of assemblies would serve

my purpose for Alley 1 and probably the remaining intersections as well. My reasons shouldbecome clear as we work through this example.
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On the second page of the wizard is where the values listed out above are entered. Hitting theappropriate buttons will allow us to configure those values.

Offset Parameters (Lane Widths):

Curb Return Parameters (Radii at EP):


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Lane Slope Parameters (Lane Cross Slopes):

On the third and final page of the wizard, we're creating a new corridor and configuring our threeassemblies into the assembly set. Since the primary road is already modeled, we're using the null

assembly there. Since the intersection is very close to being perpendicular, we will not have anyhalf sections for the secondary road. Since we will be reusing this configuration, we can save theset out for later use. The intersection can now be created.


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To finish off Alley 1, we'll grab the diamond shape grip at the end of the intersection and drag it

to the end of the alignment.

Next we'll go to the corridor properties of Alley 1, create its surface, apply its boundary, and then

paste it into the FG-Roads surface for the overall roadway.

The next intersection appears to be a 4-way intersection but the alleys here, Alley 2 and Alley 5,

are represented by their own alignments.


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Civil 3D cannot do 4-way intersections with 3 alignments. If you try, it fails to produce the curb

return profiles correctly. So to work around this, we have to treat this as two 3-way intersections.To make the program think this is a 3-way intersection, we'll temporarily move the start point for

the Alley 2 alignment away from the intersection point. This will temporarily change the existing

profile. The proposed profile will stay intact.

We then run the intersection tool on the 3-way alignment by repeating the entire process for

Alley 1.

We return the start point of the Alley 2 alignment to the intersection point; move the start point

of the Alley 5 alignment, then run the intersection process on Alley 2. Then we return the start

point of the Alley 5 alignment back to the intersection point.

Multiple Corridors for One Surface

In this example, you could create the entire roadway network in one corridor. Since there are somany baselines in the Road A corridor, the rebuild isn't instant. Creating each alley in isolated

corridors will allow us to save time on rebuilds. Plus since the entire pavement area was done in

one baseline, the triangle cleanup at the alley intersections will be better if we pasted theroadways together in one overall FG surface.
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Create the Road A surface in corridor properties using the top links. Add the corridor extents as

the outer boundary.

Create an overall roadway surface that will contain the roadway network.

Paste the surface for Road A into the overall roadway surface.


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Modeling Curb & Gutter in Parking Areas

To add the curb and gutter from Road A, we create baselines along each section of curb andconfigure assemblies containing the curb subassembly only. Since one side of the road is

catching, the other side is spilling, and header curbs are being used in various locations, the

following assemblies were created using the UrbanCurbGutterGeneral subassembly:
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To create alignments along the edges of the corridor, we extract alignments and profiles from theleft and right edges of pavement from the corridor feature lines. To do this successfully, go to the

Codes tab of the corridor properties of Road A. Change the code set to turn off feature lines that

are not associated with the top of your corridor if your default code set does not. This will ensure

that we are selecting the correct feature line for this task.

Extract:

Be sure you chose the corridor, not the underlying extracted feature line from the previousexercise or the command will not work:


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Name the alignments and profiles accordingly. There will be one alignment representing the left

and another representing the right.

Add baselines for each section of curb/gutter:

Continue to add baselines creating sections of curb/gutter:

Corridor Targets

In this example, we need to maintain the planar 3% cross slope but extend the pavement into the

parking areas while respecting the curb returns. With the Feature Line from Objects command,the edge of pavement for the corridor can be extracted from the preliminary drawing and joined
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at the intersection. There will be on feature line for the left of side Road A and another for the

right side of Road A. These feature lines do not require elevation.

Open up the corridor properties for Road A. On the Parameters tab, click set all targets, and

configure both feature lines to their respected assembly sides as Width or Offset Targets:

Slope or Elevation Targets are not necessary since we are allowing the default cross slopes in the

assemblies have control:


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Results:

Note: Select corridor and use Add a Section to tighten up small curve radii and 90 degreecorners.


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Create Simple Corridor

In this example, we have a main road called Road A and five alleys called Alley 1, Alley 2,

Alley 3, Alley 4, and Alley 5. The centerline alignments and profiles have been created for theseroads. The edge of pavement meanders along Road A because of the parking areas.

Two assemblies have been created. The assembly for Road A is planar maintaining a 3% cross

slope draining from right to left. The assembly for Alley 1 5 is v shaped maintaining 2% cross
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slopes on both sides. These typical sections will be maintained throughout the corridor. At the

intersections, the alleys will transition to the edges of Road A.

Create a simple corridor for Road A. Adjust the start and end stations to coincide with thetransition start points on the curb return. Set your frequency to 1 for tangents, curves, spirals and

profile curves.

Default frequency values can be configured on the Settings tab so that they do not have to beconfigured with each corridor.


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Currently, this corridor has one baseline with one region and no targets.

The Basics of Corridor & Assembly Planning

Corridors are 3-dimensional models based on:

Alignments

Profiles Assemblies (typical cross sectional template)

Corridors are composed of

Baselines (alignments and their associated profile)

Regions (segments along an alignment where an assembly is assigned.

A corridor can contain more than one baseline. A baseline can contain more than one region.
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Assemblies are composed of subassemblies i.e. pavement sections, curb/gutter sections, shouldersections, sidewalk sections, and daylighting instructions. Subassemblies are composed of

programming code that enables Civil 3D to do things like run quantities, change lane widths, and

gutter dimensions.

Corridors, like surfaces must rebuild when changes occur. This can be done manually or

automatically depending on your corridor settings and the size of your corridor; large, complexcorridors should be rebuilt manually.

Subassemblies cannot be stored up on the server since they are a product of a combination of

DVB, DLL, and XML files residing in your Civil 3D installation. However, they can be attachedto an assembly and write-blocked out to a central folder on the server. This can be a time saver

when working with typical sections that differ in dimensions from the Civil 3D stock

subassemblies.

When an assembly has been created, subassemblies are attached from the Tool Palettes. When anassembly has been selected, the Properties palette opens displaying the advanced parameters

controlling the physical characteristics of the subassembly.


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Help with the subassembly can be displayed by right-clicking on the subassembly in the Tool

Palette and selecting Help.

Townhouse Corridors

Townhouse corridors are complex. Parking stalls, odd transitions, and even intersections are

difficult to model with a typical section. With planning, perseverance, and a complete

understanding of corridors, near perfect contours can be created in a short amount of time.
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This workflow will be divided into the following posts:

The Basics of Corridor & Assembly Planning

Create Simple Corridor

Corridor Targets

Modeling Curb & Gutter in Parking Areas

Multiple Corridors for One Surface

Four-way Intersections with Three Alignments

Imperfect Intersections
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Imperfect Intersections