VR for Construction Planning

The biggest challenge in the construction project is to meet the project schedule. The goal of this part to investigate how VR can be a helpful tool in construction planning and to what extent VR validates, visualize and control construction processes, handle data exchange, mitigate risks, and maximize predictability.

4.2.1 4D/VR/BIM model

The 4d BIM models that integrate the time factor to the 3D physical elements started to be used in construction projects worldwide for construction planning visualization.

4D models have been used during the project lifecycle from design to utilization. It is securing efficient collaboration between stakeholders and improve the decision-mak-ing process and optimize constructability and serviceability. Several studies were con-ducted to extend 3D geometric models to VR technology. Two studies of 4D models are implemented using only BIM tools and the second model with VR capacities.

Sampaio (Sampaio, 2018) implemented the 4D/BIM model by using Autodesk Revit, Navisworks, and MS project. The Navisworks enables the interconnections among ar-chitectural, structural, and MEP 3D models and grouped elements and objects in sets related to the construction activities sequence in MS project. The new 4D model sup-ported by the time factor provides the visual representation of the construction

activities. The ability to navigate through the model enables the user to explore, ana-lyze, and extract quantities takeoff for each step-in construction work.

Figure 21: 4D BIM-VR model interfaces

The essential advantage for the software in use that allows dividing elements to sup-port the 4D construction workflow as needed. In this context, two Revit capacities are essential to support modeling of the construction workflow.

• Dividing, ability to divide a single element, or object to discrete parts for inde-pendent scheduling.

• Assembling, ability to choose any number of elements to reform a new as-sembly for independent scheduling.

With the capacities of dividing and assembling, a part can be divided into smaller units and updated automatically to reflect any changes without changing the original ele-ment. For example, a wall system or floor finishing layer can be linked to a particular activity in the MS project schedule. This BIM capacity enables to put the of a wall or floor in a sequence of operations to define an independent period in the construction schedule. BIM software can extend with the VR environment to operate a 4D/BIM model. VR and BIM can be used as a managerial tool to develop a planning stage in the construction industry, as the obstacles can be checked at the interactive virtual environment before construction in the real world. Usually, any real conflict in tion site reverts in time delay and cost overrun. The 4D/BIM model helps the construc-tion team to follow the construcconstruc-tion sequence step by step, analyze, and apply correc-tions. The contribution of BIM and VR applications reduces cost and saves materials by avoiding site mistakes (Sampaio, 2018).

Figure 20: Parametric objects

Many researchers have developed in VR technology to support the interactive visual-ization in a construction project. According to Du, the personal interaction in the virtual environment is essential to the efficiency of collaboration and communication in a con-struction project. Multiuser walkthrough helps to share immersive experience in the virtual building, allows remote interaction for project stakeholders, where project activ-ities can be visualized to analyze and optimize the construction sequence. It can also extend to integrate with the cost to create a 5D/BIM simulation for any project stage.

The combination methodology is used to improve the quantity survey of project mate-rials and equipment, which have a direct connection to the cost databases (Shia & Du, 2016).

Figure 22: 4D/VR/BIM simulation process (Cimne, 2018).

4.2.2. 4D Site Installation (simulation of the project environment)

Preparation for the project is about organizing the whole development cycle. The se-quence of the construction flow depends on various constraints that define the interde-pendencies. The project duration is depending on the execution method, the environ-ment, and resource availability. Therefore, the characteristics of site installation ments such as location, size, and parameters are crucial for project success. All ele-ments need to be matched with the planning environment to provide a realistic display of the construction flow. It helps to involve also different participants from different backgrounds in the planning process. Site installation of construction project consists of site installation objects like a machine and temporary construction like scaffolding and supply utilities like electricity supply (Hollermann & Bargstädt, 2014).

The main phases of site installation are planning, execution, operation, and removal.

Suppose the different activity requires different site installation. Therefore, the site in-stallation is an agile activity happening on the whole project duration. Until now, the 2D site installation plans are commonly used in the construction site, but it provides only information for only one action. With the complexity of site installation machines such as crane towers and concrete pumps, the site still needs more real-time data to improve the construction site flow and installation elements

Figure 23: Example of site installation and example for site installation plan (Peri, 2016)

Building Information Models are a three-dimensional objects-oriented product and linked to schedule activities. Based on the 4D BIM, the objects have different attributes for the start, end, and duration of each process. The virtual model enables to analyse the site installation to different places through a navigation tour. Avoid detection and provide a better solution if any conflict happens between site installation of workgroups.

Site installation objects have different parameters, such as performance rate.

Figure 24: Example of a crane tower and work range parameters in VR (Liebherr, 2020).

The parametric data of the site installation objects such as work range, performance rate, and geometry must include in the model. Site installation element geometry and material are modelled, such as building elements and the working field modelled as coloured area. Additionally, site installation elements need to be placed in space.

Hence the user can point out in space. It is incredibly necessary to find out where space elements are to be located while several users work concurrently by linking the ele-ments to the BIM model in the virtual environment, easy to avoid clashes between different site installation elements, and other ongoing construction. The virtual model facilitates the data transfer from planners to site workers as well as clients and other participants.

Figure 25:Visualization of site installation elements (crane tower) in the construc-tion flow model

The 4D VR model provides an effective solution for planning the logistics in a crushing environment. The construction sequence in incredible and intricate locations is a tight function as if the finished floor area is the same as the site boundary. In this case, the 4D VR model is essential to move through the project program to check how will work will develop before it is on-site execution. In the “22 Bishopsgate,” a 62-story project and will be the tallest building in the city of London. The general contractor Multiplex is constructing the building by using the 4D VR model. The VR model allows the user to check the procedures and construction sequence virtually. The biggest challenge in this project was that the finishing height of the building is just nine meters below the aviation ceiling of the city, and the fitting trial of cranes tower with that space is very risky and challenging. 4D VR allows the project team to analyze and test it in the virtual environment to ensure the safety of this step. In terms of financial cost, when the pro-jects are in hundreds of thousands or millions, the 4D VR model will be in thousands.

So, the predictable cost will be justifiable (Mills, 2017).

Figure 26: 4D VR model of the 22 Bishop gate tower (Mills, 2017).

4.2.3. 4D-VR modeling key to Dubai twin tower with the longest cantilever in the world (case study)

Project Brief

Ithra Dubai is aiming to build a new landmark in the city. The twin building is a mega mixed-use project with a 480,000 built-up area. This building is a frame structure, in which reinforced concrete is employed. While 105 meters steel bridge is connecting between the two buildings; and floats 100 m above the ground with 7,500 tones. The contract is awarded to the main lead contractor ALEC. ALEC has to manage 65 sub-contractors to cover all architectural, structural, civil, MEP, and landscaping more. The complexity and the size of the project enforce the general contractor to turn away from traditional planning methods, such as tables, 2D plans, and graphs to use the 4D virtual model as an innovative solution to solve the issues in the virtual space rather than facing it on site (Bimplus, 2019).

Figure 27: The 4D-VR model provides clear visibility into the scheduling and structure (ALEC, 2019)

Challenges

• The operation condition would be very complicated. Many activities will be per-formed at a high level from the ground, and others will be taken under the ground.

• Multiple types of activities required an advanced level of cooperation and coordi-nation. The main section on the bridge is being constructed horizontally while the two towers are being built vertically.

• Supply of materials, labor force arrangement, and any other changes will take place on the site due to the busy road.

• All the activities are supposed to complete in the shortest duration.

The twin tower is constructed in a tight schedule but also has a very complex environ-ment. The general contractor (ALEC) uses Bentleys Synchro as a service developer to deliver the virtual model. According to the project planner, the main section of the bridge would be the biggest strand-jacked lift in the middle East. At the beginning of

the project, the project team was using traditional tools to build different scenarios to mitigate risks and figure out the whole project sequence (GCR, 2019).

The planned placement of opening for supporting the crane tower did not allow the crane to work before the steel frame was installed. At the same time, the steel frame is a critical activity in the project and has the longest duration of the project completion.

The crane visualization allows finding a new path for the crane to prevent this clash.

The new path for the crane help to start the erection of the steel frame on time. Besides, the erection of the steel bridge was constructed on six operation steps instead of seven.

Figure 28: The link bridge is being constructed at a horizontal level, and the main section will slide over the road before it being strand-jacked (ALEC, 2019).

Figure 29: The erection of the steel bridge linking between the two towers in six operation steps over the road (ALEC, 2019).

Benefits and outcomes

• The size and complexity of the project can lead to collisions during the execution phase

• The use of the virtual model has detected clashes between the steel frame and crane tower over the road, cutting $12m and 40 days from the schedule. The erection of the steel link bridge in six steps instead of seven, cutting $4m and 30 days from the plan.

• Using the model as a communication and collaboration tool helps the contractor to convince the authorities to approve for lifting the link bridge.

• The virtual model helped to predict the unforeseen risks and was used as the ba-sis for early decisions. It helps to project performance, increase the efficiency for extracting the information, and save time needed to prepare reports.