Tunnel Alignment Automation with Rebar Detailing

Problem Description

  • HCI is specialised in handling Metro Projects. Underground Metro has been a complex project which mandated a scope of innovation to improve project delivery.
  • One of the major tasks recognised in this was TBM ring placement and its process of execution was performed via 2D Drawings at majority of sites.
  • EIR of New/Upcoming Projects mandated Rebar to be modelled in 3D software specifically Revit for operation and maintenance concerns in future. Thus, an effective way to execute this task was asked to be researched and tested via in-house BIM Team.
Authored by
Sangeeth Kumar. P
Head – BIM (HCI IC)

Multiple Possibilities were worked out, Quickest way among those stood out was to devise an Automation Workflow for the entire process in fractions.

  • Developing an Automation Process for TBM along with Rebar required creation of various plugins and script that would consist of Interoperability in the form of data exchange across required modelling softwares.
  • Multiple Programming modules were analysed which would accelerate the process to achieve the desired output with minimal manual intervention.
  • Tunnel detail and arrangement was provided in the form of 2D Drawings. The project consisted of creating a Twin Tunnel model for a passage of 6 KM & 5.5 KM. Entire model was required to be located. Geolocated on actual Coordinates including Ground Depth.
  • Rebar Detailing Inputs were also provided in form of 2D Drawings. Due to presence of Multiple Overlapping Layers/Regions, this required to be modelled precisely which would remove the element of doubt.

  • Process Workflow

Using Revit Dynamo for tunnel ring alignment modeling has significantly improved our precision. The automation of complex geometric calculations for curved tunnel sections ensures a perfect fit of the tunnel rings, reducing manual errors. The automated process has saved us countless hours and ensures that even the smallest design variations are captured effortlessly.
Additionally, we are planning to implement this automation across all our heavy civil ongoing and upcoming projects, as the benefits of precision and efficiency extend to other areas of infrastructure development."

Senthil Kumar Ganapathy

Vice President & Head - EDRC (HCI IC)

Methodology & Tool used

  • Primary objective of this automation has always been to enable the end user to get access to utilisation and modification of complex modelling with a Minimal UI Inputs and easy learning curve requirement.
  • Existing software utilisation was the only preferred route to integrate the process which would reduce the cost of acquiring new software kit and it’s maintenance cycle.
  • The core principle was to analyse the programming support of existing Autodesk Toolset and prepare an additional set of plugin, program tab or scripts to execute the tasks without switching to any other additional tool.

Solutions / Innovation initiatives taken

  • A TBM ring was modelled in different family categories to analyse it’s movement and rotation that is required to modify at each instance.
  • Generic model of TBM contained parameter constraints which was resolved through developing an adaptive family of the same which provided better versatility and function.
  • Rebar modelling required custom set of bend and lapse to be designed and loaded as a placeable family under Rebar Tab as there is no native support for Indian Structural Codes for Reinforcement.
  • Rebar modelling was a complex task as it required to be made in groups so that they can be easily copied, moved and rotated as per specified Geolocation.

  • Tunnel Ring

Process:

Involvement of Program C#, VB.Net, Revit API and Dynamo:

  • C#

    C# is pronounced "C-Sharp". It is an object-oriented programming language created by Microsoft that runs on the .NET Framework. C# language is close to other popular languages like C++ and Java.

  • Visual Studio

    Visual Studio is the platform to write C# program that would execute as a plugin for Revit. This means that we will compile them into *.DLL files at the end, and they will be easily distribute-able as opposed to a Revit Macro that would remain attached to a Revit project file.

  • Revit API

    It is a Application Programming Interface of Revit that helps to bridge the extensions and in software tabs via .NET complaint language such as C#.

  • Dynamo + Python

    Dynamo is the Graphic User Interface Program which is utilised to create nodes to analyse and modify Revit components. Dynamo natively supports Python Programming which can be utilised to create executable scripts for Revit within the Dynamo Interface itself.

I had the opportunity to develop a Dynamo script and an AutoCAD plugin leveraging the AutoCAD and Revit APIs, utilizing .NET and Python. By integrating these tools with Revit and AutoCAD, we created an efficient and intuitive solution that significantly optimized our design workflow. This automation reduced modeling time by 90%, greatly enhancing productivity. I highly recommend this approach for projects involving tunnel alignment and rebar placement, given its substantial impact on both precision and efficiency.

Ajay Prakash K

BIM Engineer - Metros

Dynamo script with Python Programming

Creating Parametric Families:

  • Parametric Families of TBM ring was developed on Adaptive Family Category. It is made via 8 individual segments with unique curve on both sides. It contains multiple parameters which has in-place constraints for every segment including key segment.

  • Parametric Tunnel Ring Model

  • Automated 3D Tunnel Alignment

  • Rebar Modelling was done on one of the TBM ring’s Parametric Families. It’s complexity was addressed through reinforcement menu present in Structural Tab of Revit. Bar Bending was done in conjunction to Indian Structural Code of Reinforcement.

  • 3D Reinforcement Detailing of Tunnel Ring

Creating the Required Automation Plugins / Scripts:

  • Customised Plugin were developed from scratch for AutoCAD to fetch the coordinates and slope angle from the 2D CAD Tunnel Profile Drawing.

  • Input Data extracted from CAD Drawing

  • Output from these plugins are saved in form of HTML file.

  • Coordinates and Slope Data from CAD

  • Further these inputs are fed into customised plugin for Revit which was developed via use of C# and Visual Studio’s .Net Framework. It analyses the geolocation data and creates the TBM model accurately. These are done in a batch of 50 TBM rings per execution as this automation process is dependent on the processing power of the CPU as well as hardware acceleration of graphic card.

  • Input for Tunnel Ring Pattern

  • Next stage is to enclose rebar inside these structural elements. For this task we utilise the flexibility of Dynamo and made one single input to be given i.e. to select the TBM rings in the model. Post this, there is a Python Script embedded in the Dynamo node which analyses the TBM ring and places the Rebar inside it as per requirement.
  • Upon completion, these independent file of 50 TBM rings each is stitched together in one single file.

  • Rebar Placement in Tunnel Ring

The flexibility of Revit Dynamo for tunnel projects is unparalleled. We can quickly adjust our tunnel ring alignment and rebar details with minimal effort, allowing us to respond to design changes in real-time. This enhanced level of collaboration between design and engineering teams ensures that we stay on schedule while delivering a high-quality product.

Sangeeth Kumar. P

Head – BIM (HCI IC)

Business impact: Benefits delivered (Productivity, Quality, Cost, Safety & ESG)

  • Better Coordination and Clash Detection:
    Early detection and identification of Tunnel ring position and their clashes are easily resolvable at design stage itself.
  • Improved Onsite Collaboration & Communication:
    A preview of the entire Tunnel along with Rebar gives a better support for other disciplines such as Mechanical, Electrical and Plumbing Services to plan their services and avoid clashes.
  • Model Based Cost Estimation:
    As everything is modelled in 1:1 scale, so it’s easy to take accurate quantity of every element that adds cost to the project.
  • Increase Productivity with Prefabrication:
    Pre-Visualisation of entire stretch created an efficient roadmap for fabrication team to determine number of structural elements to be prefabricated without any wastage of material due to digital model with maximum accuracy.
  • Mitigate Risk and Better Safety on Construction Sites:
    3D model provided a pathway to showcase result to all the stakeholders on site before construction began which provided an upper hand by recognising weak points where there was a sign of safety hazard. Specific areas where tunnel had change in direction orientation is approached with maximum safety which was pre-planned due to presence of Digital Model of the same.

Before & After status

Before status

  • Complexity of 2D Rebar Drawings required highly experienced Engineer on site to understand and relay the information to the involved stakeholders.
  • 2D Drawing of TBM ring alignment is not able to justify the required impact on site before construction and thus it created a room for improvement and improvisation as project moved forward in each phase.

After status

  • 3D BIM Model showed up the in-depth layer present in rebar by showing all the lapse and bend that it carried in a 3D Orbit mode. It portrayed every detail which is accessible to every user without the requirement of a learning curve to understand it.
  • Pre-Visualisation of entire alignment helped to achieve the similar design output thus reducing the scope of pivoting or modifying the elements on site.
  • It also helps in creating and tracking progress on site with correlation to model and planning the activities much more efficiently.

With Revit Dynamo, the consistency of our tunnel ring alignments and rebar layouts has drastically improved. The automation ensures that each ring and rebar placement follows the same predefined parameters, which minimizes discrepancies. We no longer have to rely on manual updates, and the consistency across projects has greatly upgraded.

V. Senthilkumar

Joint General Manager – EDRC Metros

Horizontal deployment & sustainability of the initiative

Horizontal deployment

  • This automation is specifically targeted towards the concept of rebar automation and TBM ring alignment placement. This can be applied across various projects which require rebar detailing in 3D at design stage itself. It can provide various options to be tried and tested before implementation. Similarly, placement of repetitive elements in any linear projects such as elevated viaducts can be achieved through the similar concept with minor tweaks.

Sustainability

  • This solution has been integrated in the ongoing and will be the one stop solution for upcoming underground metro / road projects.
  • We have conducted training and awareness sessions within the IC to make aware of this available solution for linear projects.
  • Across HCI, this solution will be integrated in all viable projects as an initiative by HCI BIM team.

Revit Dynamo has revolutionized the way we approach rebar generation for tunnels. The ability to automatically generate reinforcement layouts based on the 3D tunnel geometry cuts down on manual detailing work. This not only accelerates the modeling process but also provides highly accurate reinforcement schedules, which directly benefits construction and procurement

V.Sadasivam

Head - EDRC (UT SBG)
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