Fellow Engineers, Modelers, Bentley Operators, etc.
Last year in July 2017 at the 9th International Visualization In Transportation Symposium I presented an abstract detailed an alternative approach to working with Corridor/template design.
This approach is called "3D Linear Method". It is the complete opposite on what Bentley encourages in their teaching workshops, and consequently the opposite what is demonstrated by every major Department of Transport I have encountered. A brief outline on how it works:
Instead of single templates/corridors spanning the whole width of each roadway alignment, the corridors are broken up by element. 1 corridor per curb, lane, shoulder, guard rail, end condition, wall, barrier, etc. Each piece is connected to each other, eventually connecting directly or indirectly to control lines.
While this creates 100's of extra corridors, the advantages make this technique far superior to the designer, and end user (client of contractor) than the current approach for the following reasons:
1) Templates are simple, easy to create, and have no complex display rules so they are functional for the novice user
2) The same template can be re-used 1000's of times, across any project, making the data consistent 100% of the time, giving reliable consistent symbology when the data is visualized
3) The consistent nature of common templates used always simpler digital quantities to be extracted, as similar objects can be collected by symbology
4) Changes are more manageable - change only the parts you need to change, and the connectivity of all the other corridors will automatically be adjusted
5) More than 1 user can work on the same road in the same section at the same time as everything is broken into smaller pieces
6) Simpler to train - for those unfamiliar with a 3D environment, this 3D Linear Method is identical to criteria
7) Processing is substantially reduced - it is quicker to process 100's of small corridors with no complex rules than 1 or 2 massive corridors with lots of display rules by a factor of 10.
This technique has been implemented across every designer I have worked directly with in Illinois over the past 4 years, and there has been 3 distinct reactions:
a) Those with some 3D knowledge embraced it fully, recognizing that this is the ONLY way to utilize the software, no exceptions
b) Those with minimal or zero 3D knowledge dismissed it entirely, citing "This is not the way Bentley teaches it"
c) Those with medium experience recognize its power, and use a toned down version of 3D Linear method - they build templates that span all lanes, 1 for shoulders, then 1 for end conditions, for example.
Overall it has been received positively from those who understand the software's limitations, and widely used across Illinois Tollway I-294 project currently underway.
This modeling technique has caused quite a controversy here from the State Government in Illinois (IDOT) due to the radically different approach. So I wanted to hear from the greater community regarding this technique.
If you would like to contact me directly about this, feel free to do so:
Alexander Badaoui, PE: P 312.467.0123 | abadaoui@terraengineering.com
The presentation I made showing this in more detail is found here:
https://www.youtube.com/watch?v=Se8oQvVNw_w&feature=youtu.be
The attached PDF is a summary of the abstract presented.
https://www.dropbox.com/s/7jwku3ns2cu7aql/Abstract%20-%20Developing%20Visualization%20Transportation%20Models%20-%203D%20Linear%20method.pdf?dl=0
This was geared towards a non-technical audience. The following power point below is more technically driven, detailing how the naming convention operates in Illinois:
https://www.dropbox.com/s/dxq9nrm5z5vc63i/2018-03_AB%20to%20IBUG_May%202018%20-%20Part%201.pptx?dl=0
Thanks in advance for your feedback on this technique.
Hello,
We are working on a project that requires modeling 150+ driveways along a 11+ mile rural corridor. How would you all suggest modeling these with the linear method?
Also, this question is not particularly related to the linear method (which I've been exploring, and it seems great), but since there are a lot of experienced modelers here, I'd thought I'd post it here:
When you're in the early stages of planning, and the alignments and profiles can change from day to day, what's the best way to set up the corridors so that you don't have to redo your model with every change? If I want to insert a curve into an alignment, it seems that the only way is to break it and re-complex the road. However, this effectively creates a new alignment that is no longer associated with its previously dependent corridors. Edits to profiles seem don't seem too bad, because you can break it and set the new profile as active again, and the corridors will still process (although the lack of ability to insert VPIs is still a pain); it's the changes to the alignments that make me think whether or not modeling is really effective for early stages of planning.
We also experienced a situation where another colleague made changes to a profile in the SS2 way with legacy tools, but since you can't import a profile without also importing a new alignment, the change cannot be perpetuated through the 3D model without recreating everything. Is there a workaround for this transition between SS2 and SS4?
The best advance I would give you, is model using a modular approach. Break your corridors into small segments and files. Eleven miles is a long corridor to model. Many designers out there still try to model larger areas like you have described in one file and one giant corridor. This can be done, but the processing and complexity of the corridors create a lot of problems down the road. To help with processing , I would suggest modeling your pavement separate from your end conditions and also separate the driveways (civil cells) into separate files.
The existing terrain will get processed from the limits of the terrain, so clipping the existing into a smaller piece or pieces is very beneficial to processing as well. Also , only attach the existing terrain to files that require it for processing. i.e. end conditions.
Zane,
If I understand you correctly, I would model only the pavement in one file, and then reference that file into another dgn to create the end conditions based on the 3D geometry created by the pavement file. This would eliminated the need to clip the main corridor, as I can create multiple corridors for the end conditions and leave gaps where I need to insert a driveway.
Also, many tutorials on the web trains people to build the end conditions along with the pavement into the civil cell. I'm assuming I would only create the pavement with a surface template and add in the end conditions once the civil cell has been placed.
I was suggesting modeling the pavement with corridors and modeling the end conditions with corridors and point controls or linear templates. Modeling all the pavement with surface templates is difficult do the geometry limitations in ORD. Not sure about civil cells and end conditions. Seems a little complicated.
What Zane is pointing to, which he demonstrated on a project we are working on together, is the processing time for analysing end conditions with an active terrain model is very resource intensive. If you have corridors that don't require an active surface (like pavement, curbs, etc), placing them in a separate file to the corridors that depend on the active surface (like End conditions) makes the processing for both files noticeably faster than if they were in the same file.
It may not seem logical, but 2 files with less data works faster than 1 file with lots of data. I can't speak for the processing time on ORD Connect, but in SS4 it makes hours of difference in processing time, especially on large projects with multiple alignments.