The Hoffman H-Post
The idea was to ferret out any potential problems/challenges associated with a project of this nature which included exposure of concrete to sea water. The concrete support slab provided a stable foundation and runs the whole length of the seawall supporting the sidewalk and roadway. It consisted of 80 foot lengths which were 30 feet wide and 5 feet deep.
The $300 million Elliott Bay Seattle seawall was a high visibility project which was completed in just five years; the concrete support slab took about three years to construct.
This project was particularly challenging because of the concrete marine mix — a new design that never been used. This mix had to be cured differently based on ambient air temperatures. Another huge concern was that the support slab construction joint needed to be leak proof or risk leaking concrete slurry into the Puget Sound.
While pre-planning is pretty standard, this project took pre-planning to new levels.
“We treated the project like it was Spring training camp where team members can run scrimmages, do drills, and perfect skills that would be used during the regular season — because you don’t want to improvise or get experimental once the real work begins,” said Lyle Eiseman, Mortenson.
A typical/traditional pre-planning process is usually a fairly short process. The problem is that once construction is underway and the clock is started there’s no turning back and the cost of business increases dramatically.
Instead of doing things the way they have always been done, Mortenson took their inspiration from best practices from Kaizen and manufacturing assembly lines in which designers and assembly line workers get together on the line and simulate a scale model using a build out of cardboard and actually walk through a scale model of the finished product.
“We went up to our equipment facility and built two quarter scale mock-ups which consisted of formwork, reinforcing, rebar, drain pipes and construction joints,” explained Eiseman. “These were about five feet thick and ten feet wide so workers could walk around and inside them. The simulation was called 3P for Production Preparation Process.”
During the simulation and during actual construction of the concrete support slab, team members used a variety of lean construction practices and techniques. Workers practiced one touch — when you touch a tool or piece of equipment only once. For example, when dealing with material for the dumpster, trash carts were always nearby, so there was never a need to throw material on the ground to be dealt with later. You just put these materials in the right spot the first time.
On the job, team members practiced just in time delivery — inventory shouldn’t arrive onsite until it’s absolutely needed. So formwork delivered at 7:30 was used at 8 am — no taking it and laying it on the ground.
Throughout the simulation, team members practiced try-storming. This technique differs from brainstorming (writing ideas on a whiteboard). In try-storming, you come up with seven different ideas, test them out, select four and out of that, you come up with one way — typically the simplest one. This proved very useful when designing the best possible leak proof construction joint — critical in a waterfront project.
While many in the construction industry are familiar with 5S — sweep, sort, simplify, standardize, self-discipline — on this project attention was also given to 8 wastes — defects, over-production, non-utilization of talents, waiting, inventory, transportation, excess processing and motion.
Excessive motion is typical on most job sites. There seems to be a lot of working around. Why? Because tools and other resources are not conveniently located.
On this project, everything that was needed was in easy reach in the work area. Using the right people for the job whether their expertise was in carpentry or concrete was also practiced to maximize talents and minimize wasting time.
“If you fail in the 3P process, the clock isn’t ticking, and people aren’t getting nervous,” said Eiseman. “Failing is actually a good thing because you identify things that could go wrong when you go live and you don’t repeat those failures.”
Another benefit achieved during this project was improved ergonomics. Though not a specific focus of the simulation and the actual construction, ergonomics were improved by using elevated sawhorses and platforms, so workers didn’t have to bend over. Also, workers were instructed to use the two hours off/two hours on work model to minimize repetitive motion.
The team relied on integrated work plans, engineered formwork and standard work instructions throughout the project to maintain consistent and constant communication and best building practices which applied to installation of formwork at construction joints and placement of concrete.
Whether you refer to Kaizen or lean construction practices for inspiration, the goal is always continuous improvement — the idea that through practice, we can make things better for a better tomorrow.
By practicing and simulating work processes, the results here were as good as its gets: zero injuries and zero rework!