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Latest versions of GCM
In GCM++ there are two major toolbars, “GAVRAN CLASSIC” and “GAVRAN NEW”. On Fig1-01, “GAVRAN CLASSIC” is aligned along the left edge of the screen, while “GAVRAN NEW” is on the right side. Apart from these two major toolbars, new toolbar “GavranSTL”, positioned below “GAVRAN NEW”, is added in GCM++.
Fig.1-01. GCM++ Toolbars
Each of these three major toolbars further opens new toolbars, each of them referring to a particular group of commands, or modules:
- “GAVRAN CLASSIC” contains 11 toolbars, or command groups: DTM, PLAN, PROF, TMPL, GRAD, PTS, EDITRI, TUTIL, XSEC, VOL and UTIL.
- “GAVRAN NEW” contains 7 more toolbars: GCMDRIVE, DYNPROF, CSC1, CSC2, CSCi, GCMTAB and GCMPAVE.
- “GavranSTL” contains 4 toolbars: ORIENT, INQUIRE, CORRECT and BUILD.
This group of commands is intended for digital terrain modeling and the modeling of existing civil engineering facilities. By using these commands, you can generate both the TIN and grid terrain model, generate contour lines of existing and proposed surfaces etc. There are also tools for the analyses of watersheds and drainage patterns, zero-line generation etc.
Triangles representing terrain surfaces, paved areas, graded areas, retaining walls and other natural and manmade surfaces could be placed into separate layers. You can quickly generate contours with different intervals from these separate groups of triangles.
While working in urban areas, you can combine TIN models with the models of underground facilities, buildings and overpasses which could be modelled by using GCM++ tools as well. All these facilities could be included into extracted cross sections and profiles.
While working in plan projection, most existing software solutions are tangent based. That is to say, tangents are drawn first and spiral-arc-spiral shapes are added at the tangent intersections. GCM++ supports both tangent based and floating geometry. When working with floating geometry, arcs and straight sections are set first. Then, these elements are slightly rotated around specified points and connected by using clothoids. If, for example, rotation points coincide with the corners of the nearby buildings, then you can be sure that, while rotating, no element will come closer to these buildings. By using floating geometry, you can construct reverse "S" curves with no straight sections.
When working with tangent based geometry, full dynamics is at your fingertips. Any change of tangents causes dynamic changes of spiral-arc-spiral shapes. For example, move some of the tangents and the entire centerline is modified, together with its offsets, stations, labels, accompanying files ... Even crossroads behave dynamically. Left and right turn lanes, traffic isles - everything could be rearranged automatically. Move one of the centerlines from the network and all elements and centerlines linked either to this particular centerline or to one of its offsets are changed automatically (together with their labels, stations, files etc.).
By using these commands, you can literally cut longitudinal profiles out from the terrain model or from the models of the existing structures, design vertical alignment, correlate horizontal and vertical alignment, label profiles etc. While working in dynamic longitudinal profiles, points of vertical intersections, tangents and vertical curves are dynamically linked, providing creation of fully dynamic vertical alignments. By moving some elements of vertical geometry, entire alignments are recalculated and modified, together with all accompanying labels.
Cross section’s arrangement and its changes along the centerline are defined by using, the so called templates. Based on horizontal alignment, vertical alignment and the templates, triangulated 3D model of a linear facility (highway, railway) is generated. Anything that can be drawn by using LINE entities might become a template: road, runway, riverbed, tunnel, bridge. The templates are attached to the key stations along the centerline, depicting both the superelevation concept and the arrangement of the road details.
Until GCM++, there were the two basic types of 3D models: the static models and the dynamic ones. Static models are complex triangulated structures, including all the details, such as pavement layers, drain pipes, curbs etc. Dynamic models are simpler, but they are created from the dynamically interlinked triangulated networks, thus enabling automatic model rearrangement whenever the centerline is modified. The dynamic models are generated from the templates dynamically attached to the key points along the centerline (or in relation to these key points), maintaining the appropriate superelevation concept.
GCM++ introduces a new kind of the dynamic 3D model. This kind of model consists of a two seamlessly linked models: the model of the pavement and the model of the road details along the pavement edges. The model of the pavement is generated upon the pavement blocks dynamically attached to the centreline (the same blocks serving CSC – Cross Section Constructor techniques introduced in GCM2006), while the road details come from the “*.csc” files. This type of files is explained in CSC1, CSC2 and CSCi sections. Basically, CSC details are defined separately for FU, FL, CU, CL, MU and ML cases. The meaning of these abbreviations is: the first letter (F or C) tells if the particular pavement edge is on the fill or in cut, while the second letter tells if the pavement edge is upper or lower edge (higher or lower than the opposite edge of the pavement). The last two cases, MU (median upper edge) and ML (median lower edge), refer to the median cases and are used only on motorways (dual carriageways).
While the pavement model is generated as a dynamic regular triangulated network, referring to the pavement blocks attached to the centerline, the road detail models are generated along the pavement edges like triangulated “accordions”. The “accordion” contains all CSC details (FU, FL, CU, CL along the outer pavement edges or MU, ML along the median edges). Imagine that the “accordion” is compressed and when the particular pavement edge at the specific cross section of the road during the generation of the model or during the model’s dynamic repositioning comes into the Fill Upper position, the “accordion” expands into the 3D form matching FU detail. At some other point, where the pavement edge comes into the Cut Lower position, the “bellows” of the “accordion” expand into the CL form. Dynamic cut and fill slopes are subsequently constructed through the appropriate strings of POINTs that are generated along the outer edges of the 3D CSC details.
Commands from group GRAD are used for the linear and conical slope design, modelling of curbs and sidewalks at crossroads, modelling of ditches etc. Geometry of cut/fill slope is based on these data:
- the cross section of the slope
- the string of POINTs through which the slope is constructed (to the left or to the right)
- the triangulated terrain surface in relation to which the slope is calculated
This is why GRAD commands start with three editors: slope editor, string editor and surface editor. The strings of POINTs could be automatically generated along the edges of linear 3D models constructed by using TMPL commands, but could be freely placed along the pavement edges at crossroads, around the parking lots, around airport aprons etc. At the crossroads, the strings could be automatically smoothed out in vertical projection, providing the finest shapes of pavement morphology. Along the crossroad strings, triangulated shoulder or sidewalk models are constructed first, followed by the construction of cut/fill slopes.
All the features constructed by using GRAD commands (cut/fill slopes, curbs, sidewalks, shoulders, ditches etc.) are composed from the dynamically interlinked triangulated networks, just as the linear 3D models created by using TMPL commands are.
PTS (PTS – Setting Points) – With these commands, you can import surveyed data and manipulate break lines to be fitted into the terrain model. You can also position points that will serve as a base (or as a skeleton) for modeling planar facilities.
EDIT (EDIT – Editing Triangulated surfaces) – These commands support editing of triangulated surfaces, especially manmade triangulated surfaces. The editing techniques include: intersections of triangulated surfaces (usually cut/fill slopes), freehand widening of the triangulated surfaces (such as the widening of the pavement approaching the crossroad) etc.
UTIL (TUTIL – Triangulation Utilities) – With these commands, you can create some specific triangulated surfaces, either simple ones, such as rows of paired triangles representing the simplest of the building pads, or more complex, such as lakes with the island openings.
After completing the 3D model of a linear facility, cross sections are extracted from the model. Series of cross sections are literally cut out from the triangulated model. Extracted cross sections are as much detailed as the 3D model is. Pavement layers, curbs, drainage pipes and other elements of the roadway, if modelled, will be included into extracted cross sections. Even nearby buildings, underground structures, overpasses and other modelled facilities could be included into cross sections. While arranging extracted cross sections, you can perform multiple labeling and multiple volume calculations. That is to say, you can label offsets and elevations for each layer within the pavement structure, calculate their volumes as well as cut/fill volumes etc.
While the basic options for cut and fill calculations are included in the labeling options of XSEC module, VOL commands primarily support grid cell volume calculations, which are more appropriate for planar facilities. There are also the tools for finding the centers of gravity (for cut and fill masses), the tools for mass haul diagram construction, the tools for the preliminary volume assessment from the longitudinal profiles etc. By combining PTS, DTM and VOL commands, it is possible to contour the depth of cut or fill, or the thickness of the pavement overlay and accurately calculate quantities.
These commands support layer manipulation, coordinate extraction and tabulating, rescaling labels etc.
The module starts with the commands that simulate movement of vehicles along the selected trajectories, providing dynamics. It means that all the trajectories are dynamically linked to the crossroads geometry, causing automatic repositioning of vehicles, while manipulating a crossroad’s layout. Interactive techniques of puling and pushing vehicles are introduced in GCM2009 (GCMx64).
Sight distance analyses are added to this group as well. While the 3D based calculation of the available sight distances was introduced in GCM2009, GCM++ introduces the analyses of the stopping sight distances calculated from the anticipated speed levels. Stopping sight distance requirements could be transferred into the cross sections, thus supporting the obstacle removal.
This module supports the speed analyses for both passenger cars and heavy vehicles. The anticipated speed levels for passenger cars are calculated from both the horizontal and the vertical alignment of the road. Stopping sight distances, calculated from the anticipated speed levels, are used by the GCMDRIVE commands for further optical analyses of the road. Besides the generation of speed diagrams, the travel time and fuel consumption data are calculated for heavy vehicles.
CSC1 (Cross Sections Constructor 1) – Design approach introduced in GCM2006, aims to produce highly detailed cross sections directly, avoiding template definition. Simple pavement definitions (pavement blocks) are attached to the key points along the centerline first. Based on these pavement definitions, the cross grade and the width of the pavement are calculated wherever the cross section is to be extracted. Thus, these rudimentary pavement descriptions (pavement LINEs) are automatically imported into “empty” cross sections (cross sections containing existing terrain only). Finally, by using roadway details stored in “*.csc” files, detailed cross sections are automatically constructed upon the pavement LINEs. All types of two lane road and motorway details are supported: complex drainage details, nonparallel pavement layers etc. Complex cut/fill slopes and filleted slopes may also be used.
“*.csc” files are the files written in a macro-language named CSC, whose syntax reflects the geometrical reasoning underlying cross section drafting. The file contains several sections: FU (Fill-Upper), FL (Fill-Lover), CU (Cut-Upper) and CL (Cut-Lower). Each section defines specific detail to be constructed upon the pavement edge - be it in Cut or on the Fill, be it Upper or Lower edge of the pavement. In some cases, there must be also Edit section, connecting the opposite edges of the pavement. When working with motorway cross sections, there are also MU (Median-Upper) and ML (Median-Lower) details.
CSC2 (CSC2 – Cross Sections Constructor 2) – Just as the strings of POINTs are used to mark important features (usually outer edges) of the 3D model, Xstrings (XSTR) are used to identify some important positions within the cross sections. Thus, for example, by using Xstrings, the ditches can be inserted into the cross sections and manipulated vertically. Also, by using Xstrings, cross sections can “communicate” with the 3D model by importing and exporting strings into 3D. The entire CSC2 module is intended for Xstrings’ manipulation. Automated application of XSTR based commands, through batch processing is introduced in GCM++. Construction of multiple cut/fill slopes, slopes’ filleting, topsoil removal, pavement widening, insertion of ditches and retaining walls, all of it can be done in one pass, by deploying an appropriate batch file.
CSCi (CSCi – Cross Sections Constructor i) – This group supports the graphical design of CSC details.
As the pavement blocks attached to the centerline determine the pavement configuration in general, thus presenting the starting step in the whole CSC process, XPAVE group automates the definition and attachment of these blocks to the centerline. These commands create and manipulate “The Superelevation Ruler” or superelevation scheme, the linear form containing pavement-crossgrade/pavement-width definitions at each important point along the centerline. Several methods of calculating cross grades are applicable, including those based on the anticipated speed levels (or speed diagrams generated by using SPEED commands). The content of “The Superelevation Ruler” is automatically transferred into the pavement blocks and attached to the centerline.
A few commands exporting coordinates, cross sections’ data, profiles’ data, quantities and volumes, all by using a new tabular format.
For road resurfacing projects. Several methods of scraping and leveling, optimizing vertical alignment, drafting resurfacing details within cross sections.
“GavranSTL” group, with its 4 toolbars, ORIENT, INQUIRE, CORRECT and BUILD, supports the conversion of GCM models into STL (Stereolithography) models, thus enabling 3D printing of GCM models. STL models are quite demanding: there must be no holes, point triangles, needle triangles, overlapping triangles and similar defects. The whole model must be created as a “watertight” closed triangulated surface. Each of the triangle’s vertices must be arrayed in counterclockwise direction, with the triangle’s outward normal oriented in accordance with “The Right Hand Rule”. Roughly speaking, ORIENT commands deal with the orientation ad reorientation of the triangles, INQUIRE commands examine the model (mainly orientation of the triangles), while CORRECT group fixes the defects on the model. The most interesting is the BUILD group that transforms triangulated networks generated in GCM into the closed watertight model. The final model resembles the solid shell of the sufficient thickness, with the strategically positioned supports, providing structural strength and saving the printing material at the same time.
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