4D is 3D x time. 4D is what you get when you take a BIM (3D) model of your construction project and add a project schedule (or plan).

What I'm about to share is going to upset a lot of professionals, and possibly co-workers and friends. 4D is not the paradigm shift we were hoping for. Instead, 4D scheduling is an incremental improvement.

First, let's build some credibility: I've managed countless projects, big and small, since 2010 with 4D: airports, arenas, museums, hospitals, schools, bridges, condos, power plants, etc. totaling several billions of dollars. For years I was a paid consultant for Synchro to do 4D modeling and scheduling, and I've taught 4D to hundreds of professionals in construction across the USA. In 2018, a project I worked on for my current employer (Robins & Morton, a regional contractor) won Project of the Year for a global award for "Digital Construction" because of the 4D schedule.

Why would someone like me, who has invested so many years and most of my career into something and then go against that very thing? What seemed like the obvious answer to an obvious question 10 years ago now seems like the wrong answer to the wrong question.

Combining a 3D model that too few people reference with a project schedule that even fewer look at isn't "better".

My friend Jon Berkoe, whom I admire, wrote an article on the Lean Construction Blog a few months ago about 4D. Its a good read, and I encourage you, dear reader, to go back and read it. I think Jon is extremely talented and a great leader, I agree with almost everything he says, except... his solution is not realistic.

Jon's argument is that having a progressive 4D with BIM for planning and schedule validation on a continuous and inclusive basis will save time and money. Again, I whole-heartedly agree with this sentiment but the point of diminishing returns is too low.  What level of detail satisfies this?

If you scheduled and modeled to excruciating detail how much could you really save?  4D has been around long enough, if the savings were that great then we wouldn't we see more contractors adopting it?

What is 4D for?

The most important consideration to have when contemplating using 4D on your project is what is 4D good at? We can start by identifying what 4D is not good at. While we're here we should also consider what 4D is not marginally better at than the status quo.

4D is not marginally better at:

• Managing manpower
• Managing material resources
• Communicating the whole plan
• Last Planner
• accessible on mobile
• collaborative
• approachable by field staff

There's a lot to unpack here but essentially if all you have is a hammer, everything looks like a nail. Looking back at the above list, how could 4D execute on these?

When it comes to managing resources like manpower, equipment, and materials, yeah it's possible, but how is it in practice? I'll give you a clue,

4D is really good at:

• figuring out logistically challenging situations
• playing movies that win jobs

Should you use 4D BIM?

For contractors who want to win work and have the budget, 4D is an excellent tool to wow prospective clients. Usually you can hire a consultant or have someone in house put together a moel

For builders who want to eliminate waste and risk, there are some considerations to have before you go all in on 4D.

Don't get me wrong, 4D solves problems. Alice Technologies is a great example of that, their tool builds your schedules for you based off of BIM, its turned scheduling from an art to a science, and I believe the savings are real. The

Where is the paradigm shift?

J. Kevin Lloyd seems to think that CPM is well beyond its expiration date. I agree, but Oracle makes tons of cash off CPM and they will likely pay tons of cash to keep the status quo.

In the Army I was taught, "There are two types of soldiers in the Army: the infantry, and those that support us". I believe the same holds true for construction: actual workers (i.e. carpenters, iron workers, electricians, etc.) and those that support them. If we think like this, that these people are our #1 priority, we need to make sure they are kept doing productive work, have the resources (materials, information, space, equipment, etc.) they need to do their job, and are in a safe

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