Planes, trains, and trucks that are too tall for bridges: It seems that the type of infrastructure
we connect with most strongly is the kind that gets us where we’re going.
I was overwhelmed with support on the last video, and I got a whole bunch of emails from
people who share my fascination with constructed facilities.
I guess I’ve stumbled onto something here, which feels probably as good as it can feel
to find out that your life’s calling might be to talk about infrastructure to strangers
on the internet.
I’m Grady and this is What’s that Infrastructure, where we divulge and discover the manmade
world around us.
I first want to say a huge thanks to all the people who sent in photographs to me since
the first video in this series.
I kind of tried this out on a whim, and the response was much bigger than I expected,
so thanks!
The vast majority of the submissions I’ve received have been about transportation infrastructure,
so I think we’ll continue in that vein for episode 2.
A lot of people were really interested in the bridge overheight impact protection and
let me know about this bridge in Durham, North Carolina that gets hit so frequently that
someone put up a webcam and made it a website.
It’s got a sacrificial steel beam that cuts up trucks like a canopener if they’re too
tall.
Check it out at 11foot8.com
Nick Moore sent me a video of an overheight warning system
in New Zealand that looks like it uses a pair of lasers to detect if a vehicle is too tall.
Presumably there are some warning lights that would flash if the beams were broken.
Interesting to see two system serving the same purpose but on complete opposite extremes
of cost and complexity.
Nick has a YouTube channel I like a lot with short tidbits of science and engineering,
and I’ll put a link to it in the description.
If you’ve ever driven into a tunnel on a sunny day, you know that feeling of being
plunged from brightness into complete darkness and there’s a period of time where you’re
basically driving completely blind while your eyes adjust.
Andreas sent in these pictures of a tunnel in Gothenburg Sweden that has a sunshade before
the entrance to allow driver’s eyes to adjust more gradually to the darkness.
Very cool idea, and even cooler because Andreas’s grandfather was one of the engineers that
helped design this system.
Tunnels aren’t just for people though.
Charlie from Scotland sent in a picture of a project he worked on that included a culvert
under a new road, not for water, but actually for badgers.
This provides a quote-unquote “mammal underpass” so that local wildlife can safely get across
the road.
Dylan sent in this photo of a freeway sign in California and was curious about the angled
frame around it.
This one stumped me, I’ve never seen something like this, so if you know what this is, let
us know in the comments.
If you ride a motorcycle, you might recognize this photo from Iwan in the UK.
This is an inductive-loop traffic detector which is used by a traffic signal to determine
if a vehicle is stopped at the light.
A metal vehicle stopped over the loop will induce eddy currents, reducing the inductance
which can be sensed by the light controller.
Some loops have a hard time sensing small vehicles like motorcycles which can leave
you stuck at a red light that never switches, so some riders install a magnet on their bikes
to try and increase the chances of triggering the light.
Dan is the county engineer for a county in Iowa, and he sent in this video his crew driving
a pile using a vibratory hammer.
Dan told me that they do all their engineering and construction with in-house staff which
is something you don’t see too often.
Here they’re using a traditional gravity hammer to check the bearing for the piles.
They’ll measure how far the piles moved after a certain number of blows from the hammer
and check that against the specification to determine if the piles pass or fail.
And speaking of bridges, you might know that the two most common materials used for in
their construction, steel and concrete, actually expand and contract due to changes in temperature.
For long structures like bridges, thermal movement even over the course of a single
day, can be on the order of inches or feet.
And civil engineers have developed quite a few ways of accounting for movement in bridge
designs.
Karl Jansen sent this photo of a bridge beam supported on a massive steel roller and this
photo of an interesting expansion joint.
Karl posts cool civil engineering photos on his blog which I’ll link below.
Greg sent in this photo of a bridge in Washington that’s supported on one side by a rocker
on a steel plate.
And here’s another rocker on a bridge in Connecticut sent in by Adam Buchbinder.
Jan sent in this photo of a bearing plate from a bridge in Wroclaw, Poland.
I thought it was interesting to see the CE marking on the name plate.
Structural bearings have strict regulations in Europe to ensure their safety.
Blaise sent in this photo of his kids Joe and Peregrine standing next to a huge roller
support on the Sorlie Bridge in North Dakota.
They also found a USGS stream gage mounted on the bridge.
Very cool to see kids interested in infrastructure.
Finally, Alvin sent in a photo of some pistons connected to bridge beams.
I believe these are lockup devices that allow the bridge to expand and contract due to normal
thermal movement to keep stresses from building up.
But, in the event of a strong motion event like an earthquake, the pistons resist movement,
locking the beams and columns together so the bridge can act as a composite structure
and minimize the chance of failure or falling debris.
Again, huge thanks to all the people who sent in photos.
If you’ve got a cool picture you’d like to share, send it in to Whats.That.Infrastructure@gmail.com.
Make sure you mention that it’s okay for me to use in a video, and include your mailing
address.
If I use your photo in a video, I’ll send you a Practical Engineering sticker.
For those wondering about the project videos, I promise I’m working on one, but with studying
for the PE exam and the brutal august heat in the garage, things are just taking a bit
longer.
Not to hype too hard, but it is the most awesome project I’ve ever worked on and it includes
lasers, so stay tuned.
As always, thanks for watching, and let me know what you think.