**3.2 Horizontal-vertical alignment**

*Models and Technologies for Smart, Sustainable and Safe Transportation Systems*

plied, and stores the result in a digital file for easy retrieval.

Civil 3D, Open Roads Designer, ArcGIS, etc.

Breakline Data, and Contour Data.

Digital Terrain Modeling (DTM) is a concept that underlies all calculations in Civil Engineering involving elevation or slope - profiles, cross sections, grading and

The process of DTM involves the creation of a data structure that the software can instantly "touch" to retrieve elevations or slopes, representing either existing or

DTM mathematically completes all interpolation possible between the data sup-

Surfaces can certainly be produced from other data types, including point data. There are certain data types that are universally applicable to any DTM effort in Civil Engineering and Surveying. These data types are constant in any program:

The three data types which can be used in constructing a DTM are Point Data,

• Point Data - Point Data for DTM consist of individual discrete X, Y and Z locations, without connecting features between them. Typically, these will be spot elevations in a contour drawing, or the mass points themselves in a Mass Points and Breaklines drawing. Critically, the Point Data must have an elevation or Z component that can be processed in some fashion in building the elevation model. Spot elevation text at elevation 0 in a drawing can be used and processed by Map into an ASCII file, and ASCII files of XYZ format can be used as well.

• Breakline Data - Breaklines are also referred to as Faults, or Features.

Breaklines, as used in this context, represent the linear edges of site features along which there is a noticeable change in grade. Successfully applied, a breakline forces a deflection in a contour to show a grade change. Examples are edges of pavement, shoulders, toes or tops of slope, toes or tops of wall, water features, etc. λ Contour Data - The definition of contour Data for Digital Terrain Modeling is very specific, and not necessarily what one would expect.

• Contour Data are strings of point data connected by segments in complex objects; the CAD representation is a polyline. Contour Data do not have to be at constant elevation, as one typically thinks of contours. Contour Data are a fast means of selecting and processing point data, utilizing the vertices of the objects. Most Digital Terrain Modeling applications will also process the segments between the vertices as breakline data, and can filter out vertices too close together or add interpolated vertices if required. Contour Data must be at a correct Z elevation to be processed in a Terrain Model. Polylines must be at a correct Z, either constant as a 2D polyline, or varying, as a 3D polyline. GIS data can again be used, and CAD Map can read elevation attributes from GIS Contour Data and apply them to polylines through a Property Alteration Query.

Most Civil Engineering and Surveying applications will utilize some combination of data types in a Terrain Model; having two types present is common and all

Triangular irregular networks (TIN) are a representation of a continuous surface consisting entirely of triangular facets, used mainly as Discrete Global Grid

**3. Road modeling**

volume calculations.

proposed conditions.

**3.1 Digital terrain model**

**240**

three is not unusual at all.

in primary elevation modeling.

Creating and defining a horizontal alignment is one of the first steps in infrastructure design.

In **Figure 3** a workflow to design and edit alignments is shown.

You can draw the alignment geometry as a polyline, and then create the named alignment from that geometry. For greater control, you can create an alignment object or You can also make edits to alignments using grips.

Create alignments in many ways, such as creating them from polylines, from pipe networks, and from LandXML data.

The alignment can be created using fixed, floating, and free elements:

• Fixed elements have its position totally defined by specifying a combination of start/end points or center, length, bearing or angle, and radius. However, as the fixed position of a computator is defined by points that are dependent (referenced) on other elements, a fixed computator is actually free to move as the referenced elements move. It is "fixed" in respect of its location to the referenced element;

**Figure 2.** *Digital terrain model.*

**Figure 3.**

*Workflow: To design and edit alignments.*


Once it is determined which element type best suits the design context, it can be selected the appropriate line, curve, transition, or combination based on available design data, such as whether you have a known through point, length, or radius.

When you create an alignment, you can use the criteria-based design feature to ensure that your alignment design meets minimum local standards and consequently easily identify and report standards violations.

The alignment is an interactive line with profiles, both existing ground and planned work.

Using profiles, you can view changes in elevation along a horizontal alignment. In addition to the centerline profile, you can create offset profiles for features such as waterway or ditch banks. On a profile view, you can also superimpose the profile of a different horizontal alignment that is in the same area. And like LandDesktop you can create a temporary profile that can help you view information at locations where there is no alignment (i.e. line, polyline, feature, or along a series of points you select).

The horizontal and the vertical alignments need to match in length exactly or else the corridor will not be created properly.

**Figure 4** shows an example of road alignment with its relative ground and vertical profile.

Once both alignments are created, the next step is to create a section type, with surface depths, sub-earth depth, kerbing, banking, etc.

**243**

**Figure 5.**

*Section types. (a) Fill, (b) bridge.*

*BIM Approach for Smart Infrastructure Design and Maintenance Operations*

Assembly objects contain and manage a collection of subassemblies that are used

An assembly is an 3D drawing object that manages a collection of subassembly objects. Together, assemblies and subassemblies function as the basic building

Adding one or more subassembly objects, such as travel lanes, curbs, and side slopes, to an assembly baseline creates an assembly object. This forms the design for

It is also possible to create more advanced assemblies referred to as conditional assemblies. A conditional assembly contains one or more conditional subassemblies, which apply subsequent subassemblies when specified conditions at a given

In **Figure 5** is shown a typical section type for fill and in presence of a bridge. Specific BIM-based tools as Subassembly Composer/ Generative Components provide an interface for composing and modifying complex subassemblies, without the need for programming. Without the need to be an expert in programming, users can create custom subassemblies to meet their specific needs, making corridors

For example, in presence of a retaining wall characterized by a variation of the geometric characteristics in terms of height/weight along the road layout, it is possible to create a flowchart (see **Figure 6**) set with decision variables that change as

In the case in question, the section changes dimensional characteristics as the

distance between the road surface and the ground surface changes.

a corridor section. The subassemblies are provided in a set of catalogs.

*DOI: http://dx.doi.org/10.5772/intechopen.94242*

to form the basic structure of a 3D corridor model.

blocks of a roadway or other alignment-based design.

**3.3 Section type**

*Road alignment and its vertical profile.*

**Figure 4.**

station are met.

have endless possibilities.

the boundary conditions vary.

*BIM Approach for Smart Infrastructure Design and Maintenance Operations DOI: http://dx.doi.org/10.5772/intechopen.94242*

**Figure 4.** *Road alignment and its vertical profile.*

#### **3.3 Section type**

*Models and Technologies for Smart, Sustainable and Safe Transportation Systems*

• Floating elements have one unknown, which becomes the "floating" part. The unknown part can be the length, angle, point/centre, or radius. The other parts

• Free elements are totally unconstrained and will be defined by the adjoining elements. Whilst an arc has two unknowns with only the radius, or one point,

Once it is determined which element type best suits the design context, it can be selected the appropriate line, curve, transition, or combination based on available design data, such as whether you have a known through point, length,

When you create an alignment, you can use the criteria-based design feature to ensure that your alignment design meets minimum local standards and conse-

The alignment is an interactive line with profiles, both existing ground and

Using profiles, you can view changes in elevation along a horizontal alignment. In addition to the centerline profile, you can create offset profiles for features such as waterway or ditch banks. On a profile view, you can also superimpose the profile of a different horizontal alignment that is in the same area. And like LandDesktop you can create a temporary profile that can help you view information at locations where there is no alignment (i.e. line, polyline, feature, or along a series of points

The horizontal and the vertical alignments need to match in length exactly or

Once both alignments are created, the next step is to create a section type, with

**Figure 4** shows an example of road alignment with its relative ground and

(one for lines, two for arcs) are fixed in position;

quently easily identify and report standards violations.

else the corridor will not be created properly.

surface depths, sub-earth depth, kerbing, banking, etc.

or length defined.

*Workflow: To design and edit alignments.*

or radius.

**Figure 3.**

planned work.

you select).

vertical profile.

**242**

Assembly objects contain and manage a collection of subassemblies that are used to form the basic structure of a 3D corridor model.

An assembly is an 3D drawing object that manages a collection of subassembly objects. Together, assemblies and subassemblies function as the basic building blocks of a roadway or other alignment-based design.

Adding one or more subassembly objects, such as travel lanes, curbs, and side slopes, to an assembly baseline creates an assembly object. This forms the design for a corridor section. The subassemblies are provided in a set of catalogs.

It is also possible to create more advanced assemblies referred to as conditional assemblies. A conditional assembly contains one or more conditional subassemblies, which apply subsequent subassemblies when specified conditions at a given station are met.

In **Figure 5** is shown a typical section type for fill and in presence of a bridge.

Specific BIM-based tools as Subassembly Composer/ Generative Components provide an interface for composing and modifying complex subassemblies, without the need for programming. Without the need to be an expert in programming, users can create custom subassemblies to meet their specific needs, making corridors have endless possibilities.

For example, in presence of a retaining wall characterized by a variation of the geometric characteristics in terms of height/weight along the road layout, it is possible to create a flowchart (see **Figure 6**) set with decision variables that change as the boundary conditions vary.

In the case in question, the section changes dimensional characteristics as the distance between the road surface and the ground surface changes.

**Figure 5.** *Section types. (a) Fill, (b) bridge.*

#### **Figure 6.**

*Modeling retaining walls using subassembly composer. (a) Workflow, (b) result.*

Once your assembly is built you need to apply this to your alignment using the corridor function and hey presto, you will have a corridor and basic road design.
