When Welty-Boldt Production Engineer Graham Ryan tells a trade partner that he’s getting on the train, the partner isn’t going to be watching the bucolic views unfold along the Cuyahoga Valley Scenic Railroad.
The train Ryan is talking about is an outgrowth of Takt Planning, part of the lean process being used to construct Akron Children’s new medical tower, slated to open in spring 2015.
“Takt is derived from a German word meaning meter or rhythm,” said Ryan. “It allows construction to proceed with predictability and reliability. Picture a manufacturing line but instead of parts moving down the line, it’s people.”
Each floor of the new building is divided into 1 to 4 areas. A crew, with specific construction responsibilities, completes its work in 1 area in 5 days, then moves on to the next. Another crew builds on what has been completed, again finishing in 5 days.
Each crew represents the car of a train. The train works its way through the building, an area at a time, completing everything from electrical, plumbing, and dry wall hanging, through lighting, flooring, painting and interior design, until the building is complete.
“Crews don’t need to wait until an entire floor is done,” Ryan said. “They just wait for an area to be completed. The time savings can be counted in weeks.”
This location-based scheduling differs from the more traditional approach, where all the trade partners work together at the same time on the same level of a building.
“The traditional approach can be a free-for-all, as everyone competes to get their own work completed, creating quality and safety issues,” Ryan said. “Sometimes dry wall is hung before electrical or plumbing is completed, which results in tearing down the walls to finish what’s behind them.”
Using Takt, electrical and plumbing cars are in the front of the train, so those crews arrive in each area first to complete their work before the car representing the crew hanging the dry wall arrives.
Although this process results in faster construction, Ryan stresses that reliability is more important than speed.
“Each crew commits to having its work in each area completed in 5 days, so we not only know when the work will be finished, but we know that each task is completed accurately before the next step begins,” he said. “Information, materials and equipment, and safety procedures are in place before the next train car arrives.”
Since the same crew stays in the same train car throughout the entire building, the learning curve is very short.
“The crews are doing the same thing continuously,” said Ryan. “With no down time, they don’t need to relearn the tasks, so they become more productive and quality improves as they move through the building.”
Although this approach was first used in the construction of the Empire State Building in 1929, it languished until embraced again recently by companies using Lean construction techniques like Akron Children’s building project.