[Note that this article is a transcript of the video embedded above.]

Construction is something you probably either love or hate, depending on your commute or profession. Obviously, as a civil engineer, it’s something I think a lot about, and over the past 6 years of reading emails and comments from people who watch Practical Engineering, I know that parts of heavy construction are consistently misunderstood. Also, I talk a lot about failures and engineering mistakes in my videos because I think those stories are worth discussing, but if that’s all you ever hear about the civil engineering and construction industries, you can be forgiven for having an incomplete perspective of how things really work. So I combed through YouTube comments and emails over the past few years and pulled together a few of the most common misconceptions. I’m Grady and this is Practical Engineering. In today’s episode we’re debunking some myths about construction.

Myth: Construction Workers Just Stand Around

If you’re one of those people who hate construction, this is probably a frustrating image: one guy running the excavator and everyone else just standing around just watching. It seems like a familiar scene, especially when the project’s schedule is dragging along. But, looks can be deceiving. Think of it this way: contractors are running an extremely risky business on relatively thin margins. In most cases, they already know how much money they’ll be paid for a project, so the only way to make a profit is to carefully manage expenses. And what’s their biggest expense? Labor! A worker standing around with nothing to do is the first thing to get cut from a project. Individual laborers might be paid hourly, but their employers are paid by the contract and have every incentive to get the job done as quickly and efficiently as possible. So why do we see workers standing around? There are a few reasons.

Firstly, construction is complicated. Honestly, it’s a logistical nightmare to get materials, subcontractors, tools, equipment, and workers in the right place at the right time. Almost every task is sequential, which means anything that doesn’t line up perfectly affects the schedule of everything else. Construction is a hurry-up-and-wait operation, and the waiting is often easier to spot than the hurrying. Most of the folks you see on a construction site, whether they’re standing around or not, have been or will be hustling for most of the day, which leads me to my second point: construction is hard work.

Anyone working in the trades will tell you that it’s a physically demanding job. You can’t just show up at 6AM, run a shovel for 10 hours, go home, and do it again the next day. You need breaks if you’re working hard. Standing around is often as simple as that: workers resting from a difficult task. Plus a person with a shovel isn’t that useful when you have a tracked excavator on site that can do the work of 20. So, the laborers you see outside of machines are often doing jobs that are adjacent to the actual work like running tools, directing traffic, or documenting. That leads me to my third point: not everyone on a construction site is a tradesperson.

Keeping an eye on things is an actual job, and in some cases it is more than one. Inspectors are often on site to make sure a contractor doesn’t misinterpret a design or build something incorrectly. An engineer may be on site to answer questions or check on progress. And trust me, you don’t want us anywhere near the cab of a crane or excavator. Safety spotters are sometimes required to keep workers out of dangerous situations. Plus, foremen and supervisors are on site to direct their crews. These folks are doing necessary jobs that might look just like standing around if you’re not familiar with the roles.

Lastly, construction is often out in the open unlike many other jobs. Confirmation bias makes it easy to pass by a construction site in a car and notice the people who aren’t actively performing a task while ignoring the ones who are. If those construction workers stepped into any office building, they might see you hanging around the water cooler talking about your favorite YouTube channels and start a rumor that office workers are so lazy.

Myth: Ancient Roman Roads and Concrete Were Better

I made an entire video comparing “Roman concrete” to its modern equivalent, but I still get emails and comments all the time about the arcane secrets possessed by the ancient Romans that have since been lost to the sands of time. It’s not true, really. I mean, the ancient Roman concrete used in some structures did have some interesting and innovative properties, and the Romans did invest significantly in the durability of their streets and roads. But, I think a Roman engineer would be astounded to learn that most modern highways handle hundreds of thousands of trucks that can weigh upwards of 80,000 pounds before being replaced. And, I think a Roman engineer might wet their toga if they were to see a modern concrete-framed skyscraper. There are a few reasons why it seems that the Romans had us outclassed when it comes to structural longevity.

First there’s survivor bias. We only see the structures that lasted these past 2,000 years and not the vast majority of buildings and facilities, which were destroyed in one way or another. Second, there's the climate. I haven’t personally been to the parts of the world surrounding the Mediterranean Sea, but I hear most of them are quite nice. Cycles of freezing and thawing are absolutely devastating to almost every part of the constructed environment. The ancient Romans were in an area particularly well-suited to making long-lasting concrete structures, especially compared to the frozen wastelands that some other of Earth’s denizens call home. Finally, there’s just a difference in society and government. Ancient Rome was wildly different from modern countries in a lot of ways, but particularly in how much they were willing to spend on infrastructure and how they were willing to treat laborers. Modern concrete mixes and roadway designs are far superior to those of ancient Rome, but our collective willingness to spend money on infrastructure is different too.

I think a lot of the feedback I get on Roman construction is based on the extremely pervasive sentiment that “we just don’t build stuff like we used to.” It’s an easy shortcut to equate quality with longevity, especially for infrastructure projects where we aren’t directly involved in managing the costs. I regularly have people tell me that we shouldn’t use reinforcing steel in concrete, because when it corrodes, it decreases the lifespan (which is completely true). But also, unreinforced concrete is essentially just brick. And not to disparage masonry, but there’s a lot it can’t do in structural engineering.

A lot of people even go so far as to accuse engineers of using planned obsolescence - the idea that we design things with an intentionally limited useful life. And I don’t know anything about consumer goods or devices, but at least in civil engineering, those people are exactly right. We always think about and make conscious decisions regarding lifespan during the design of a project. But it’s not to be nefarious or create artificial job security. It’s because, in simplistic terms, the capital cost of a construction project and its lifespan exist on either side of a spectrum, and engineers (by necessity) have to choose where a project sits between the two. Will you build a bridge that’s inexpensive, but will have to be replaced in 25 years, or will you spend twice the money for more concrete and more steel to make it last for 50? We make this decision constantly when we pay for things in our own lives, choosing between alternatives that have various costs and benefits. But it’s much more complicated to draw that line as the steward of tax dollars for an entire population.

That’s why engineering exists in the first place. With an unlimited budget, my 2-year-old could design a bridge that carries monster trucks over the English channel for a million years. Engineers compare the relative costs and benefits of design decisions from start to finish to meet project requirements, protect public safety, and do so with the limited available resources. Part of that is evaluating alternatives like the cheap bridge versus the expensive bridge, plus their long-term maintenance and replacement costs to see which one can best meet the project goals. In that case, planned obsolescence means being a good steward of public money (which is always limited), by not gold-plating where it’s not necessary so that funds can be used where they’re needed most.

Myth: Lowest Bidder = Lowest Quality

There’s a story about legendary astronaut John Glenn being asked by a reporter about what it felt like to be inside the Mercury capsule on top of an Atlas LV-3B rocket before takeoff. He reportedly said he felt exactly how one would feel sitting on top of two million parts - all built by the lowest bidder on a government contract. And indeed, most construction projects are contracted using bids, and regulations require that public entities award the contract to the lowest bidder. Those rules are in place to make sure that the taxpayer is getting the most value for their money. But, it doesn’t necessarily mean that our infrastructure projects suffer in quality as a result.

Most construction projects are bid using a set of drawings and a book of specifications that include all the detail necessary to build them. An engineer, architect, or both has gone to great lengths to draw and specify exactly what a contractor should build, often to the tiniest details about products, testing, and procedures. You can see for yourself; just google your city or state, plus “standard specifications,” and scroll through what you find to get a sense of how detailed contract documents can be. We go to that level of detail in defining the project before construction so that it can be let for bidding with the confidence that an owner will end up with essentially the same product at the end of construction, no matter which contractor wins the job.

Bidding on contracts is a tough way to win work, by the way. Imagine if on January 1st, your employer gave you a list of all the tasks that needed to be complete by the end of the year, and you had to guess how many hours it would take. And, if you guessed a higher number than your coworker, you got fired. And if you guessed lower than the actual number of hours it took, too bad, you only got paid for the hours you guessed. It might incentivize you to look for innovative ways to get your job done more efficiently, but (admittedly) it might also encourage you to cut corners and ignore opportunities to add value where it’s not explicitly required.

Many public entities are moving away from contracting using the lowest bidder model for types of procurement that allow them to recognize and award other measures of value than just cost like innovation, schedule, and past experience. These alternative delivery methods can help foster a more collaborative relationship between the owner, contractor, and designer, making the construction process smoother and more efficient. But, the lowest bidder model is still used around the world because it generally rewards efficient use of public funds. After all, John Glenn did make it safely to space, became the first American to orbit the earth, and came back with no issues on those two million parts provided by the lowest bidders.

Myth: Foundations Must Go To Bedrock

If you’ve ever played minecraft, you know that at a certain depth below the ground, you reach an impenetrable layer of voxels called bedrock. And indeed, in most parts of the world, geologic layers do get firmer and more stable, the farther down you go. Engineers often take advantage of this fact to secure tall buildings and major structures using deep foundation systems like driven or drilled piles. “Bedrock” is such a familiar concept that it’s easy to look at the world through minecraft-colored glasses and assume there’s (always and everywhere) some firm layer below - but not too far from - the surface of the earth, and all tall buildings and structures must sit atop it. But, the real world is a little more complicated than that. Different geologic layers may be considered bedrock, depending on whether you’re a well driller, foundation designer, pile driver, or geology textbook author. There’s no strict definition of bedrock, and there are vast spectrums of soil and rock properties that might make stable foundations depending on the loading and environmental conditions.
In engineering especially, there doesn’t always exist a firm geologic layer at a reasonable depth below the surface of the earth our buildings and structures can be attached to. And even if there is, that may not be the most cost-effective way to meet design requirements. There may be shallow foundation concepts that are appropriate (and much cheaper) depending on the situation. There’s a famous parable about a wise man who built his house on the rock, but not every wise man can afford a piece of property on the rocky side of town, especially in today’s real estate market. Civil engineers don’t always have the luxury of founding structures on the most stable of subgrades, so we’ve come up with foundations that keep structures secure on sand, silt, clay, and even floating on water. When the rain comes down, and the streams rise, and the winds blow and beat against our structures, they almost always remain standing no matter what the geology is below.