Timeline Matrix

The problem with Gantt charts

Gantt charts are long task lists. Without the left half of the Gantt chart, known as the bar chart, this task list would be useless.

Gantt charts are not glanceable. With an average of 75-100 activities per tabloid-sized page and 2,000 activities per $100M of construction value, you’re left with hundreds of pages of task list.

Do you want to know when you need to install lockers on the 3rd-floor spa? You’ll need several minutes of page turning to find your dates.

Want to know what’s blocking you and how much wiggle room you have in your start and finish dates? You can try all day, but you’ll never find the answer to this.

Do your dates seem a bit off? Are you curious what the scheduler has blocking you? Too bad, the schedule provides hard dates, start and finish only, with no indication of how flexible or important your activities are.

What if designs were communicated like Gantt charts?

Construction documents typically include sets of sheets for each discipline, for each floor, for each elevation, with no shortage of cut sheets, details, and cross sections.

This means the structural column on the first floor will appear in multiple drawings: the first floor plan for all disciplines, any enlarged floor plans, the column schedule, the foundation plan, and possibly a few details. It’s important to note that you may find specific information about the column in certain locations and other information in different places. In some instances, the column serves primarily as context for other elements in the design.

The design documents are communicated in many dimensions, primarily x, y, and z, with additional information layered on top.

If designers provided designs like we provided schedules using Gantt charts, then we would get something like the following:

Sometimes we would get designs broken up by discipline, sometimes not.
The architect would design the Structure, MEP, finishes, etc., with no input from consultants.
Like milestones, Grid lines would move with every revision.
One grid line wouldn’t move until the very end of the project, and it would be an as-built.
There would be no details on how different building elements interface with each other.
Huge areas like the pool would be completely missing.
Enlarged floor plans would be issued just weeks before they were worked on.
Instead of a mechanical room design, we would just get a label that says Mechanical Room.
There would be one drawing only for the entire design.
The design would be redesigned every two weeks.
Nothing would be clouded.
The project would be about 30% larger than originally planned

The last one is generally true due to design-related change orders. Imagine if we had properly planned and executed a project, we could see a 30% increase in efficiency.

As Dwight D. Eisenhower famously said, “Planning is essential, plans are useless.” What he meant was that figuring out what needs to be built, how to do it, in what order, identifying roadblocks, and assigning resources, etc, the process of doing that is essential. The final product itself, especially your first version, is often useless. Once again, the process of creating the plan is crucial, but the plan itself is likely not of any use.

With that in mind, we cannot reasonably expect extreme detail; after all, tasks are represented by days, not hours or minutes. Additionally, it’s often best practice to limit tasks to one subcontractor each, and each task should release work for another subcontractor (See checkpoints if you want to get more detailed).

Additionally, in construction, things happen all the time that mess with plans. That doesn’t mean we should plan as if everything will go perfectly. There should be some wiggle room in our plan to account for these. Designs have tolerances, and schedules should, too.

Some will say that if you show the wiggle room to the subcontractors, the first ones will take it all. This is true in CPM, not LeanCPM, as the wiggle room is built in on the front and back of each task, and spread between milestones.

What if schedules were communicated like designs?

We would have a plan for each trade or group of trades, with other trades shown for context.
We would have ‘section cuts’ for critical areas, like an “Electrical Rooms” plan.
There would be key plans included in the schedule.
The same task would show up on multiple pages to show dependencies.
Sheets would have different axes; the x-axis represents time, but the y-axis can represent labor, area, or work quantity, etc.
Sheets would be color-coded according to trade or other metadata.
Views would be provided to show the quantity of work and productivity for different tasks.
We would have fewer pages and less paper to print on.

Goals

Goals are represented as rectangles in the timeline matrix view. Depending on their relative size, they may show just the name of the goal, but they could also show a summary of their tasks.

A note on redundancy

There is no doubt that there is redundancy in the timeline matrix view. However, this is still significantly less redundant than Gantt charts. In a Gantt chart, we often see the area of work the task refers to in the task name itself. So you might see “Area B Level 3” written on 200 activities. Whereas in a timeline matrix, you’ll see the same “Remove Reshores” task within a few different Areas and Goals (e.g., the structural and buildout goals).

This form of redundancy is more accessible.