1-2-3 Revit: BIM - Small, Medium? Extra Large!

Revit Worksharing helps teams collaborate on projects of all sizes

Over the past several years, the building industry's interest in BIM shifted from evaluation to implementation. Some firms take the immediate plunge into large-scale, mission-critical projects (see my previous article on how firms in South Africa have used BIM).

Others elect to start using BIM on a small pilot project -- testing the BIM waters before rolling out the system with more people on larger projects. But once they start, companies quickly see the advantages of BIM and are eager to use it on larger projects.

In this month's article, I'll describe how Autodesk's purpose-built BIM solution, Autodesk Revit, supports projects of all sizes -- from small residential projects to large, complex commercial building projects -- through Revit Worksharing.

Fits All Sizes
Revit Worksharing distributes the power of its parametric building modeling environment across the project team by offering a range of collaboration modes, letting design teams choose the best way to interact based on their workflow and project requirements.

For many projects, the team can simultaneously access a shared building model and ad-hoc editing of building elements as needed. Firms can divide large projects into discrete shared units -- usually based on separate architectural systems (core, envelope, etc.) or other physical features. For very large building projects made up of discrete wings or individual buildings, the team can separate the project into individual linked models.

On-The-Fly Editing
A purpose-built BIM system such as Revit typically reduces the manpower requirements of a project by coordinating the building information model and documents automatically. Given this happy circumstance, fewer people are required to complete a project. As a result, many projects only need a handful of users at any given point. The team simply shares the project model dynamically -- each user contributing his/her skill set when appropriate. If more than one person happens to be working on the building model at the same time, on-the-fly editing of model elements (a door, a wall, etc.) is accomplished in Revit via element borrowing.

Element borrowing lets multiple users dynamically access and edit shared portions of a project model, but nearly eliminates the possibility of editing conflict. When a user action causes an element to change, Revit checks to see if another user is editing that element. If it's not in use, Revit automatically assigns that element to the user, at which point other users are prevented from manipulating it. If it's already assigned to someone else, Revit provides a message to that user, asking if the first user can borrow that particular element for modification. If the answer is yes, Revit reassigns ownership to the requesting user. If no, Revit denies the request, providing a message to the first user informing him/her of the situation.

Zones of Responsibility
For very large projects and design teams -- where users need to simultaneously work on different portions of the project at the same time -- Revit Worksharing allows projects to be formally divided into worksets. This mode is also appropriate when a project manager wants to explicitly assign responsibilities for parts of the project to team members and limit access to others.

A workset is a logical grouping of objects in a building project that is reserved for editing by a single user at a time. Worksets usually correspond to specific zones of responsibility such as various architectural systems (shell, core, interior, ceiling, etc.) or physical features (stories, wings, tenants, etc.).

A user checks out a workset and works independently in that model, periodically posting changes back into the master project file and refreshing the workset with changes from other users. When done, the user relinquishes control of the workset by checking it back into the central file.

Worksets make it easier for an extended design team to work concurrently on a building project by limiting the prospect of multiple users trying to change the same element. As an example, one user is working on interior partitions and another is laying out furniture in the same area. To keep from bumping into each other, two worksets are created: one for interiors, one for furniture. Although all the elements of both worksets can be displayed, elements within a workset can only be edited by the user who checked out that workset.

Continuing with the example, because the ceiling grid matches the partitions, it makes sense for it to be in the interiors workset. The feature of element borrowing, described above, still allows components to be dynamically allocated to a user for specific editing irrespective of their workset assignments. So if the furniture layout user wants to edit a couple of furniture-specific light fixtures in the ceiling grid, he can do so on-the-fly by borrowing them from the interiors user. But depending on the situation, it might get tiresome to constantly ask for permission to borrow elements. In that case, the ceiling grid could be in its own workset, checked out in whole by whoever needs to modify it.

In addition to limiting editing conflicts, worksets can also improve the performance of the system by controlling graphic display. Worksets can be displayed as needed, avoiding the memory-intensive display of parts of the building model that aren't necessary for a specific design activity. For example, you may constantly want to see an exterior workset, whereas the display of the furniture workset can be toggled on or off to suit your needs.

Linked Models
Finally, for the very largest projects (especially multi-building projects or buildings with discrete wings) Revit Worksharing allows individual Revit building models to be linked together. Standard model-viewing mechanisms are supported for linked models, enabling a wide range of drawings to be created across the linked model; for instance section drawings spanning multiple buildings, or site plans. And similar to worksets, linked building projects also contains unique display settings, controlling how much of the overall project is displayed, which improves graphic performance.

Worksharing in Action
Founded in 1945 in Honolulu, Wimberly Allison Tong & Goo http://www.watg.com (WATG) is an architecture, design, planning and consulting firm with 300 employees in seven offices (Honolulu, Newport Beach, Los Angeles, Seattle, Orlando, London and Singapore) currently working on projects in 50 countries. The firm is a leading designer in the hospitality, leisure, and entertainment sectors.

In 2002, after a two-year evaluation and pilot projects period, WATG selected Autodesk Revit as its BIM solution. Starting with small projects that fit a predefined profile, WATG tested ideas about how BIM-based tools could improve the quality of design and documentation while increasing efficiency and productivity. These initial projects were relatively small projects, requiring limited use of Worksharing strategies.

Their initial implementation has grown to the point where WATG is now using Revit on large, complex projects such as the Quinta do Lorde Hotel and Marina Resort complex located on the island of Madeira off the coast of Portugal.

This 230,000 sq.ft. complex, due to begin construction in spring 2005, was modeled in Revit. The multi-building project is separated into discrete building models, linked together on an overall site plan. Each building model has a variety of worksets based on building systems and workflow, and the entire project file can be accessed by a design team located in WATG's North America and Europe offices. "When we first started using Revit, it was a challenge to model very large projects," admits Jim Balding, WATG's Revit implementation manager. "Things have really changed in just a few years! Now we're tackling projects of all sizes with relative ease - from clubhouses and villas to our Quinta do Lorde resort project with more, even larger projects, in the works."

Summary
State-of-the-art BIM with Autodesk Revit is proving itself on a range of projects - from small to very large. Firms are finding that Revit Worksharing provides the necessary range of collaboration features for their project design teams, customized to suit their unique requirements.

For BIM, one size may not fit all, but one BIM solution - Autodesk Revit - does fit all sizes.

Reference
Multi-user Collaboration with Revit Worksets whitepaper from Autodesk.