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.
This video is sponsored by Brilliant,
the best way to learn math and science through problem solving. More on them later.
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.
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.
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.
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.
Building infrastructure is such a cool confluence of technical fields, combining
engineering, public administration, construction management, and a whole lot of skilled trades. I
think one of the easiest shortcuts to success in school, your career, or just life in general is
finding opportunities to mix and match areas of expertise like this. In niches, there are riches,
as they say. But it’s hard to gain technical knowledge in outside industries. That’s why I’m
thankful for Brilliant, the sponsor of today's video, for providing interactive courses in
topics that interest me, like this one about using logic to debunk false information. Sound familiar?
My videos give a thousand foot overview of many parts of engineering, but maybe you’re
watching one of my videos and thinking, “This is for me. This is what I’m interested in.”
Brilliant gives you the ability to dive into math and science topics so you can really learn
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and they’ve put a ton of effort into finding the best ways to help you gain technical knowledge
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at brilliant.org/PracticalEngineering. You don’t pay anything to sign up, and the first 200 people
that use the link will get 20% off an annual premium subscription. Again, it’s completely free
to sign up. That link is in the description. Thank you for watching, and let me know what you think.