Optimising Survey Terrain In In Roads Final

Editor's Notes

• #2: The title of this presentation is “Optimising Survey Terrain in Inoads”. Richard has worked on some of the largest road projects undertaken in the State of Victoria over the past 20 years and has extensive experience in both the public and private sectors. His specialist expertise lies in the usage of InRoads and 3D terrain modelling. He has made presentations at previous local and international industry forums. Within PB, he is internally accredited as a Principal CADD Associate and is a member of the PB Global CADD Steering committee. Richard is the Principal Designer in the Melbourne Office and is currently seconded to the Tulla Sydney Alliance project
• #3: What is being looked at in this presentation is the project on which saw this new InRoads innovation, the importance of the survey, the usual method used for creating the survey and the improved streamlined method. In addition to this, we will see how models are combined and carved up to be useful for a range of InRoads 3D modelling purposes.
• #4: The M80 Ring Road Upgrade will improve the 38km Western and Metropolitan Ring Roads, from the Princes Freeway at Laverton North to the Greensborough Highway at Greensborough. The upgrade will improve safety, ease congestion, reduce travel times and improve reliability for all road users, especially during peak periods. The M80 Ring Road Upgrade is a $2.25 billion project, jointly funded by the Victorian and Australian governments and is expected to take more than 5 years to complete.
• #5: The following practice was developed on the Tulla Sydney Project for the widening of 8kms of road on the M80 Western Ring Road ($500M+) as an Alliance Project in Melbourne, Victoria, Australia.
• #6: The Tulla Sydney Alliance project begins in the vicinity of Steeles Creek, immediately west of the Calder Freeway Interchange. It then proceeds through the Airport Drive Interchange, Melrose Drive Ramps an the freeway to freeway interchange at Tullamarine Interchange. The road continues down through a the Moonee ponds creek gully, past the cut and cover tiunnel at the Pascoe Vale Road half diamond interchange, past Merlynston Creek and finishing in the vicinity of the Sydney Road Interchange.
• #7: The Project is of an Alliance kind unlike Design and Build (Construct) or a direct design. The key ingredient of an Alliance Project is that it is a partnership between State DOT, the Contractor, and , Design consultant. In an alliance venture the key parties are on the same team and have a different working relationship than that of a straight contractual nature. The risk borne by the project is the risk shared commonly together. Profits and losses are shared and distributed through the Alliance on a commensurate basis. These projects “share the gain and wear the pain”. The situation where one party has an advantage over the other does not exist.
• #8: The location of the Tulla Sydney Alliance Project is adjacent to the Greensborough Entry Ramp to the M80 on the Tullamarine Interchange at 122 Melrose Drive. It is a 20 minute drive from the city and 5 minutes to the airport. Being adjacent to the road construction makes it convenient to travel to site for inspections as the site is at the back door.
• #9: Too often projects go astray and lose time with the mismanagement of survey in the design environment. It is thought that if anyone can handle the survey why not give it to the junior drafter and free up the more valuable resources. The best potion for any project to be in is for the surveyor to pick the survey up in the field to the correct specification and issue the design team with a 3D CAD fie and in this case an InRoads digital terrain model of the same data. In my experience, this rarely happens. The job of creating the digital terrain model is often passed on to the designers to sort out. The survey is an extremely important component of any project. The whole of the design is based upon the survey. Therefore , if the survey is incorrect, the consequence is that the design will be also.
• #10: The survey is undertaken to attain a particular accuracy. The most common accuracy for road reconstruction projects is PAV 2 which provides a point accuracy of +/- 25mm ( 1inch in imperial measurement)
• #11: In the design office, the first task is to manage the survey and create the digital terrain model (.dtm) for the design to begin in the third dimension by establishing gradelines prior to the formation of the model There is a lot of confusion in the industry as to what constitutes a good digital terrain model, and, 4 different methods are most commonly used. Some would form dtms from 3D triangle wireframes displayed from other packages, some from a series of generic spot levels and breaklines, some from features with generic names, and, some would form a dtm correctly by creating features with intelligence.
• #12: It is sometimes said that importing triangles as breaklines provides the best result as the digital terrain model (dtm) will reflect the same result as what came from the surveyors package. It may do so but the file will be 5 times the size and all the features and spot levels will be lost. This type of dtm is very limited in functionality and is degraded.
• #13: The importing of spots and breakliones with generic description is also a method employed to create dtms. The shortcoming is also the degradation of the model with losing the feature name descriptions. All the breaklines are allocated a generic named layer so the ability to interrogate a linestring to ascertain what it is is lost. The lip of kerb cannot be distinguished from the back of kerb or the front of the kerb with this method.
• #14: This is similar to the previous example but the original data is no longer generically named but the import process rationalises the data out to assign a generic name. The shortcoming again is also the degradation of the model with losing the feature name descriptions. All the breaklines are allocated a generic named layer so the ability to interrogate a linestring to ascertain what it is is lost. The lip of kerb cannot be distinguished from the back of kerb or the front of the kerb with this method.
• #15: The most valuable type of dtm created is one where the features have intelligence so that like features can be interrogated and behave differently. The input symbology can be recreated and further options are opened up for display purposes and reduce drafting efforts.
• #16: The summary of import method shows that there are quick ways to create dtms that do not provide the value that they could. This is really summarised by taking a shortcut at the outset which will provide a long term penalty for the remainder of the project. In the consulting game, it is too easy to take the cheap and nasty route which will later turn around and bite you.
• #17: The same summary can be viewed in the table and its very apparent to see the differences in value according to the number of gold stars. The methods employed that have the least import time also have less integrity, less intelligence, and are less useful for editing. The issue of the triangle import is the worst where all the features are swallowed up in the triangle facets. Each side of the triangle also provides an overlap where every breakline is duplicated and the file size grows 5 times as large, also affecting the processing and handling times. What happens frequently is that users can’t be bothered to correctly import the surface as named features because it will hold them up in the work. This practice only transfers extra effort and cost down the line to the other users. What if there is a way to speed up the import of named features?
• #18: The normal import time can be time consuming. This dialog box is found under the file<import<surface command and each individual groups of like identities are imported one level at a time. Sometimes the selector button is used to separate different types of features contained in the same level e.g. topographic breaklines and topographic spots sharing the same level but are different entities. The time taken to use this import method may be between 1 to even three hours and this is repeated at every time when there is a survey update. This is reason why some users compromise the import so they can do it quicker. What if there is a way to do this just as quick or quicker than the inferior methods? The answer to that is there is!
• #19: Until recently, 6 months ago, this new feature hadn’t been known or investigated by the group of InRoads designers in our immediate circle. Most Designers are like the magician who only practices his same old tricks. Why? Because they work. When a new feature is introduced it is quite often ignored or overlooked because everything appears to work quite well as it is. But, is it cost effective and efficient. The Import Surface Advanced was introduced in the XM series of InRoads and is located under the more familiar import surface command. It works on a number of rules that are setup to determine how the CAD data is processed by isolating by symbology and writing to feature styles. Therefore, the breaklines and random points, exterior and interior boundaries will have triangulation instructions assigned to them and also names and descriptions. These rules are captured and stored in the xin preference file
• #20: The first step is to create the rule set. In this case it is for survey but it could also be for the proposed design. By adding the Kerb_Lip and opening it up to edit, a description is added, a feature style and a point type of breakline is assigned. This gives the rules of how it will be processed.
• #21: The next step is to capture the symbologies with the selection criteria. Elements can be filitered by level, type, colour, linestyle, weight or cell name. The match element properties captures the toggled items by using a picker directly onto the CAD element in the MicroStation file. The elements captured can be displayed as highlighted elements in the CAD file with the Highlight Matching Elements button
• #22: The selection criteria can be reviewed individually to show what attributes have been selected. In this case for the Kerb_Lip we can see that the types of elements that are to be picked up are those that contain Arcs, Curves, Lines, Line Strings and Shapes. It is not restricted to one type but may include multiple. It is the same for each of the other selection criterium
• #23: For this particular example, the kerb_Lip will include all the elements that have the defined symbology of level = 16 Kerb Lip, Type = Arc, Curve, Line, Lline String, Shape; Colour = 7; LineStyle = 0; and, weight =1
• #24: After the XIN file is completed for all the symbologies and features, the import process is completed and stored away ready to be used every time an import is needed from the CAD graphics. Open up the same dialog box, have the levels turned on in the CAD display and press apply. The data is imported. Then to complete the process, surface triangulate. Bingo – the import is complete
• #25: In this case, the existing surface was imported in 90 seconds and processed in another 90 seconds and all automated according to the rule set. And this was no small file. It contained 1616,802 Breaklines, 3902 Exterior Boundary points, 229 Interior Boundary Points, and, 28,905 Random points. When triangulated a total of 224,472 triangles were created in the Digital Terrain Model. This is a large terrain model!
• #26: If we now look at the surface summary Import Methods, it is demonstrated with this new method that the import time has been addressed with respect to time depicted on the bottom left by the red star. There is now no reason as to why the feature naming can be ignored.
• #27: Two basic survey dtms are used for the project. The first is a consolidated feature survey which comprises of a stitch up or joining of 5 individual surveys, all undertaken at various times under different contracts. The second survey formed is a composite survey extending far beyond the perimeter of the feasture survey and includes feature survey (PAV 2), photogrammetry survey (PAV 4) and Topography determined by older contour bases. The Consolidated feature survey is the most accurate and is used for most design purposes and the Composite is used as a supplementary terrain model for drainage and other evaluations.
• #28: The Feature Survey files originally consisted of 5 individual files tahat were picked up under different contracts. For these to be their most useful, they needed to be joined together as one file. Interfaces were matched and exterior boundaries were added to form one single digital terrain model
• #29: Once the feature survey was stitched together, the overall composite model could be formed. The first step was to join 3 photogrammetric based surveys shown in the darker blue and to splice in the consolidated feature survey. The merge surface command was used initially for this. As time moved on in the project, manual splices were sometimes used.
• #30: Once the feature survey was merged with the photogrammetry, the topogarphy shown in mustard could be added to form an overall composite. As can be seen this was quite and included a 10 x 120 kms area i.e. 120 sq kms.
• #31: As the project was being designed and constructed simultaneously with the design office just keeping in front of construction, additional survey was being identified and fed back into the process after the initial foramtion of the models. The areas in crimson show some of the additions. This is where the real value adding becomes apparent with the innovation of the import surface advance command as the processing time is reduced dramatically, a bit like using cruise control in your vehicle.
• #33: Now we need to have a micro look at what has been happening in the background prior to the creation of the dtms. There was one item in particular that needed to be addressed. When the feature survey comes in, it comprises of ground survey, bridge road surfaces, bridge undersides (soffits), and, bridge piers, columns and abutments. Any two points in the horizonatl position with a vertical difference will not triangulate successfully as they occupy the same position and are what are called crossing breaklines. The consequence is that all data crossing over other data needs to be removed. Therefore, the bridges are stripped from the consolidated dtm to form additional dtms, one for the Bridge Road Surface and another for the soffits or undersides. The existing dtms now amount to 4.
• #34: The slide depicts the feature survey as it was received showing the bridge crossing over ground features on the valley floor of Steele Creek
• #35: The first step is to remove the bridge from the ground features
• #36: The next step is to isolate the bridge road surface and create a single dtm. A consolidated dtm is formed with all the other bridge road surfaces
• #37: Following that, the bridge underside/ soffit is isolated on all other bridges to form a single dtm.
• #38: A section cut through the three surfaces, the Bridge Road, Bridge Soffit and the ground consolidated features shows the digital terrain models
• #39: The digital terrain models pertaining to survey do not stop there. The other models that are created include the Road Boundary, Pavement, Open Graded Friction Course (OGFC or OGA) Strip, No Go Zones around High Voltage Lines, Sub Strata surfaces from geotech boreholes, and, utilities like sewer and gas.
• #40: This diagram shows two of the auxiliary dtm models that are formed and are typical for every highways project. On the left we see the edge of the road reserve. In this case, the line at the boundary is draped on the existing surface and imported as a non-triangulable named feature. When this surface is cut with a cross section, the feature is displayed as an annotated cell to show the boundary. The other surface is the existing pavement. This is created from a copy of the consolidated feature surface dtm where a new exterior boundary is created at the pavement edge and interior boundaries are brought in for median gaps. The surfcae dtm symbology is then changed to display a hatched user defined linestyle. Whenever this pavement surface is cross sectioned, the pavement extents are clearly depicted with the hatching.
• #41: Another auxiliary model is one that was created to remove a non structural layer of asphalt from the existing surface. A wearing course known as Open Graded Friction or Open Graded Asphalt is laid on top of the Freeways to reduce tire noise from vehicles and to remove water from the pavement. Water filters through this layer and seeps out at the edges. The challenge is to recreates the surface with 30mm of OGFC stripping removed
• #42: The OGFC is not always visible on site, sometimes it is and appears as a step, and sometimes it is hidden in barriers, kerbs and edges of pavements. Each part of the road had to be assessed individually and rules as what to do with each scenario were made to determine the formation of the dtm
• #43: Another auxiliary model is one that was derived from historical records of the high transmission towers and wires and catenary pick up in the feature survey. The pylons were modelled in 3D in MicroStation. They were positioned from the survey feature base and from the high transmission wire surveyed at the connecting points on the tower
• #44: The wire that was picked up in the field was the one closest to the road. The remaining wires were generated and projected across with InRoads.
• #45: In grey to the right of the freeway are the transmission towers.
• #46: The new works not only a lateral clearance from the wires, but a vertical clearance. Further to these requirements, a clearance to a worst case scenario needs to be catered for. The no go zone is calculated from a day where the temperature reaches 72 degrees C with the wires swinging through 30 degrees. This was ascertained from historical design records, digitised and corridor modelled in 3D in InRoads.
• #47: The blue at the base is the ground features shown by triangles. Displayed above the ground in grey is the modelled clearance diagram under the swing area, and above is the swing. Being modelled in 3D as components assists in the checking and optimisation of the design.
• #48: Further survey terrain models are created to establish rock level surfaces from the boreholes observations taken prior to the initial construction of the freeway. The information is taken from a spreadsheet, pasted in a text file and imported into InRoads as a COGO geometry file, primarily to identify each log. A specific Wizard is set up to do this and captured in the XIN file to speedup the task.
• #49: The output can then be displayed as COGO geometry and the style allows a cell to be placed with Borehole Number, Easting, Northing and RL. Any borehole can now be located quickly in MicroStation with a text search for the borehole number.
• #50: The Text Import Wizard is also setup and captured in the XIN file to bring in the rock surface. The rock level is than captured as a surface containing random points which can be cut and displayed in cross sections and longsections.
• #51: Another survey model created is a utilities one. Services such as water, gas and sewer are surveyed or recreated in 3D in MicroStation. They are then imported into a utilities dtm as non-triangulable named features. When sectioned, these features are picked up in their true position and displayed as annotated cells bearing the diameter and description of the named feature.
• #52: Is the handling of survey related dtms are small matter? After nine months into this project, more than 50 digital terrain models have been handled and processed, including 30 continual updates.
• #53: The handling of survey is a key component of any project, the bigger the project the more comprehensive the task is. Survey needs to be resourced from the job’s outset. If not, that may impact on the availability of a designer and impede the delivery of the project. The task and effort in handling the survey is no small task and should not be underestimated. The most efficient and value added models are the ones that are formed correctly with named features The new “Import Surface Advanced” function provides the automated ability to achieve this quickly at the snap of the fingers. This function brings excitement and enthusiasm back to creating correctly formed digital terrain models in InRoads.
• #54: Questions will be taken at this closing point