Whitepaper: 04.26.2012

Making the Case for 4-D

Linking the project schedule to the 3-D BIM model is providing real benefits at St. Jude Medical Center in Fullerton, California.

Building Information Modeling (BIM) continues to revolutionize efficiencies during the design and construction process. In the hands of a true builder, utilizing 4-D software at the job-site level to enhance the communication amongst all parties is proving an effective extension of the 3-D model. The definition of a 4-D schedule is a schedule linked to a 3-D model. This integration provides a graphical representation of the traditional Gantt chart, as well as offers the project sequence in the form of a short movie or animation. The animation software utilizes the schedule tasks, logic, durations and timeframes, providing an accurate graphical representation of the work sequence as outlined in the schedule. While a 3-D model is a useful representation of the project in a final condition, it is static as it relates to time. The 4-D representation can reflect the project at any stage of construction.

Project Background
The St. Jude Northwest Tower project is Southern California’s first 100% design-build hospital project. The project consists of a four-story, 200,000-square-foot hospital and a 15,000-square-foot central plant. McCarthy has an excellent relationship with the St. Joseph Health System after completing four very successful projects where innovation and excellence are a continued expectation and delivery from McCarthy.

The St. Jude project is utilizing two different types of scheduling approaches to plan the project. Each method is able to produce a 4-D simulation — Line and Balance and the traditional Critical Path Method (CPM) scheduling approach. Line and Balance scheduling requires a model to first be resource-loaded with quantities. It then uses production rates in order to determine durations. The software being used to accomplish this task on the St. Jude project is VICO.

The project team is also using Synchro, 4-D software that uses the CPM schedule to link to the 3-D model. While both VICO and Synchro can produce 4-D simulations based on a schedule, this case study will focus on Synchro.

Project Uses of 4-D Simulation

Project Safety
McCarthy is constantly planning for and implementing new ways to make the company’s jobsites safe and injury free. With this vigilant focus on safety, the project team at St. Jude is using the 4-D simulation to talk to staff and subcontractors about current potential safety issues in the field. This is very important as it is more than reviewing a 3-D model; it is examining the way the field conditions actually look right now.

One example of this coordination relates to the locations of heavy equipment and current blind spots the construction has created. The team also reviewed the closed temporary road and opening of a new access road for the hospital. The issues arising from this were reviewed using the model so the subcontractors could be aware of new traffic patterns.

Pre-Planning Sessions
The project team at St. Jude held a preplanning meeting with the structural steel erection subcontractor. The sub had been told that it was a very tight site with extremely limited access for trucks, deliveries and the crane. Nevertheless, it was not until the project team presented the 4-D model to the subcontractor that this was truly clear. The 4-D simulation revealed the condition of the site at the time the steel was to be erected. Fortunately, this meeting was held months prior to erection giving the subcontractor ample time to develop a feasible and productive erection plan and to determine the proper equipment.

Weekly Subcontractor Meetings
Most projects have weekly subcontractor meetings in which a “look-ahead” schedule is distributed. While the St. Jude project is no exception to this, the project team takes these meetings to a new level. While the team does distribute Gantt-style schedules, the team also presents the 4-D simulation of work to come over the next few weeks.

Unlike other meetings, there is no flipping through drawings trying to explain the upcoming construction activities. Site logistics are also discussed using real time 3-D representation of the field. For example, a change in site and hospital delivery access posed new challenges. Much more than simply knowing where to take deliveries, the change in traffic patterns meant large trucks would have to take an entirely different route to exit the site. Rather than planning in the field once the conditions changed, McCarthy was able to communicate with the subcontractors prior to the road change, reducing confusion in the field.

Owner Communication
In addition to the ongoing monthly scheduling reporting on the project, McCarthy also provides the owner with weekly updates to report progress. More than simply telling the owner what is ongoing and if work is ahead or behind schedule, the team at St. Jude uses photos and 4-D to enhance communication.

The use of photos is nothing new when reporting progress to project stakeholders. The limitation, however, is that photos cannot reference a schedule to determine the status of the project. The use of the 4-D scheduling solves this issue. Every week the Synchro 4-D schedule is updated to the same day a photo is taken. The picture and the 4-D schedule are then presented together to clearly convey the project’s status. Furthermore, the 4-D simulation generates visual representation of the project on a monthly basis. This is created with the baseline schedule so at any month the owner can review the project by simply viewing and comparing photos with the following sample Synchro screen shots:

Conclusion
4-D scheduling has moved from simply being a buzz word or the flavor of the month to a real solution that the St. Jude Northwest Tower team has embraced. It is a practical tool that leads to increased safety, schedule and cost savings, as well as increased productivity. 

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