Big Owners are not satisfied with the ROI their GCs are getting from BIM.  (That was certainly the case at the Dallas AGC BIM Forum.) They feel they have already paid for coordinated drawings and model, so clash detection ROI is not enough. Instead, Owners are looking for true ROI with schedule compression. If the model has been coordinated, and all elements can be quantified, why can't buildings be built faster? Using model-based quantities and optimal productivity rates to drive the Location-Based Management System is the solution.

Model-based quantities

GCs in the US are increasingly using 3D models to perform quantity takeoffs. To enable schedule compression by the use of LBMS, the quantity takeoff needs to produce the following information:

~ Quantities for each task

~ Quantities for each location

Quantities for each task

Each line item in the schedule should have at least one associated quantity item. A task in LBMS is defined as "work which can be completely finished by one crew in a location before moving to the next location."  Therefore, tasks should only contain scope which can be performed by one subcontractor. Any task which hands work off to another subcontractor should be included in the schedule.

Because this means that, for example, formwork and rebar need to be quantified, either a very detailed model is required or specialized quantity takeoff software, such as Vico Office Takeoff Manager, needs to be used.

Quantities for each location

LBMS requires quantities by location. Location Breakdown Structure is a critical planning decision. We have seen projects where a change in project's Location Breakdown Structure resulted in schedule compression of 10% with no increase in resource requirements or risk. To achieve this, Location Breakdown Structure needs to be an automatic, real-time feature of the construction management system, allowing different scenarios to be tried and quantities to be recalculated on click of a button.  Vico Office has a dedicated LBS Manager to achieve these functions.

Optimal productivity rates

The US construction industry typically schedules using historical durations which are not based on quantities, productivity rates, or resource assumptions. Therefore, the goals and total durations of projects are defined based on historical performance. Production rate requirements or resource needs are not known because they are thought to be the subcontractor's problem. This is, in my opinion, the main reason why the ROI of BIM has not been consistently achieved so far.

Historical productivity databases, such as RS Means, do exist. They have similar problems. Productivity has been measured based on average productivity in projects which did not use methods to improve productivity. Because the resulting standards include a lot of waste, using these productivity rates will bloat durations or result in excessive resource needs.

Instead of using historical productivity rates, optimal productivity rates should be used for planning. The goal is to provide optimal circumstances for the subcontractor to do work. When the subcontractor starts, the location should be clean, all RFIs resolved, as-built data of previous trades available, model and drawings should be coordinated, materials available and all prerequisite work completed. In addition, there should be continuous flow from one location to the next to remove starts and stops and to maximize learning benefits. If all this has been done before the subcontractor starts, workers will be able to achieve optimal productivity. They are only constrained by their skill level and production rates of predecessor tasks. This optimal productivity has been tracked separately from average, historical productivity in Finland and has been shown to be 10-40% higher, depending on trade.

The ROI of BIM can be achieved by creating optimal conditions for subcontractors, quantifying those optimal conditions, and adjusting subcontract agreements to reward the GC for providing optimal conditions.  The subcontractors need to produce according to agreed-on production rates when optimal conditions are available and to completely finish one location before moving to the next location.  Together with schedule optimization and prevention of cascading delays, these productivity gains should allow reliable schedule compression of at least 20%, concentrating on finishes and MEP phase. Location-based Management System, together with software tools such as Vico Office, makes this schedule compression possible.

To read more about schedule compression, please review the Kamppi Center Case Study.  This massive multi-use facility in the heart of downtown Helsinki was completed six months ahead of schedule.

We have a demonstration of Vico Control from the Phoenix AGC BIM Forum.  Klorman Construction illustrates how you can use the alarms in Control during your forecast meetings to prevent bottlenecks and crew pile-ups in advance.

We also offer two informative webinars:

BIM 401: Model-Based Estimating

Scheduling Strategies in a Hard Bid

Tell me your experiences.  When you complete a coordination meeting, do any of the resolved issues result in schedule compression?  Are you able to generate shop drawings from the coordinated model which equals more pre-fabrication off-site and streamlined assembly on-site?