For the next eight minutes, we're going to talk about traffic. Why? Because it's fun to know things!
For example, did you know the study of traffic flow is an insanely
complex field of mathematics and civil engineering?
I know nothing about either of those things, but since we're on the internet
there's nothing stopping me from pretending like I do!
Traffic is frustrating for everyone, but especially for those who are working to improve it.
If you're an engineer and you're trying to figure out the best design for a building,
you could eventually find your way to a solution.
But, if you're an engineer trying to figure out how to design roads for mass transportation...
Good luck!
The amount of factors involved in the flow of traffic are practically endless!
The reactions of individual drivers, the fluctuating population of communities...
the activity level of various locations during any given time of day, motor vehicle accidents...
road construction... road conditions... the city's budget... the weather...
The list is long and our runtime is short, you get the idea.
Perhaps the biggest headache for the folks in charge of road construction is the dreaded interchange.
A road junction where you can access major highways through entrance and exit ramps.
Highways are high speed, but eventually, you need to get off of them, so that means slowing down.
Interchanges are utilized to provide a safe method for cars to either get on the road or get off the road
while avoiding the rest of the cars that need to keep going.
Here's the problem though, intersections are TERRIFYING.
Where two two-lane roadways intersect, there are thirty-two opportunities for drivers to collide into each other.
Have fun sleeping tonight knowing that, but there's good news to be had.
Engineers are finding ways to fix this. Enter the Diverging Diamond Interchange.
First employed in 1970's France, the design has been retooled and is now slowly,
yet surely, making its way to the United States.
I know this because I live in Springfield, Missouri, the first city in the US to use them.
Springfield is the perfect mass transit guinea pig. It's a former small town with a growing population
that has the perfect mix of back roads and multi-lane monstrosities.
Traffic fluctuates depending whether college is in session or not, and on top of that,
being smack dab in the middle of Tornado Alley means our fair city can be used to test
the latest and greatest traffic innovations against a variety of elements.
The first Diverging Diamond Interchange in America was opened here on June 21, 2009,
at Kansas Expressway and Interstate 44.
If you're from around my neck of the woods, you know this area was notorious
for backups during peek hours of the day.
Like, one to two-mile backups. Waiting twenty-five minutes or more was not
uncommon, especially in the event of an accident.
Today, thanks to the Diverging Diamond Interchange, traffic moves through this area in a matter of minutes.
In fact, the Interchange was such a success story,
Popular Science magazine featured it as one of the best new engineering innovations of 2009.
Today this Interchange design has expanded to other trouble spots in the city,
including National Avenue and James River Freeway...
Kansas Expressway and James River Freeway...
Chestnut Expressway and Highway 65...
and Battlefield Road and Highway 65.
Let's head out to this one and see how it all works.
This is the intersection of National Avenue and James River Freeway.
Two high traffic roads that have tons of congestion during peek hours
thanks in part to the nearby hospitals, which account for a large portion of Springfield's employees.
This is what it looks like when you are driving down National, and you cross over James River.
Taking a right onto the freeway seems pretty straightforward.
But driving straight through involves crossing over to a completely different side of the road
and heading down a windy path of windy-ness.
All of this looks and feels terribly confusing the first time you do it.
The tilted traffic lights in the middle here made me freak out the first time I drove past them,
yet for whatever reason, when you follow the dotted line...
you're not sure why it works, but it just does.
Things look like a convoluted mess of lines, lights, and barriers from the ground...
but when you take to the skies, things become a bit clearer.
Here's a quick mock-up of how things worked before the new system:
Intersections were placed on either end of the entrance and exit ramps,
which resulted in constant stops and traffic backups
here, here, here, here, here and here.
The new system temporarily shifts the traffic into the opposite lane,
and allows vehicles leaving an easier way to exit, while the vehicles continuing down the road
can move along at a steady clip controlled by traffic lights.
This allows for two-phase operation at all signalized intersections,
cars no longer have to clear opposing traffic when making long turns, making things much safer.
Long story short: The new system is designed to shorten the time you're stopped,
and these barriers coupled with this lane design eliminate opportunities for car accidents.
Check this out, huge semi-truck takes the exit ramp onto National Avenue.
Under the old system, this semi would either have had to stop at the intersection and wait for a green light,
or if there was a designated turning lane, he or she had to stop and wait for room to make his or her turn
while having an obstructed view if other cars happen to pull up too far.
This means the truck could be stopped for around sixty seconds or more,
which would cause a traffic backup on the ramp, which would stretch out onto the freeway itself.
Very dangerous. A lot of accidents happen this way, believe me.
The new system? He yields for a few seconds...
and he's on his way!
Or she... you get what I mean.
The truck's stop time is shortened, there's plenty of space for other vehicles to cohabitate,
the driver's field of view is no longer obstructed, and because the same system is being employed
on the other end of the interchange, the traffic that stopped the truck before is moving.
So...yeah, no backup.
By the way, I love this. Check out how easy it is for big rigs to make a left onto the highway now.
No stop.
Easy visibility and they've eliminated the possibility of accidents from oncoming traffic
because there IS no oncoming traffic. That's been shifted to the other side of the road.
Flip the pic around, and you'll see the benefits go both ways.
Now maybe this makes sense to you, maybe it doesn't.
But let's address the biggest complaint naysayers seem to have about this design.
Mainly: "It's too confusing to know what to do!"
It really isn't. The cool thing about this design is that... well, you don't really have an opportunity to mess up.
If you had never seen this intersection before and you suddenly came upon it, you'd come to a stop
at the red light, and once it turned green, you'd follow the lane... and you'd get through it!
These barriers prevent you from driving anywhere other than where you are supposed to go.
The road itself is designed to eliminate the chances of collisions.
There are thirty-two potential accident spots at a regular interchange, this design lowers that to fourteen.
Now, when the Diverging Diamond Interchange was first proposed in America,
it got a lot of flak from this guy, Charles Morone.
A "recovering" engineer whose major complaint was that the design was ugly,
unfriendly to pedestrians and likely that it looked so wonky, that more accidents would be caused by
people who didn't understand how it worked than anything.
In fact, he made this- like- cutthroat video lambasting the design in 2011 practically forecasting its utter failure.
Well, it's been seven years and rather than spawning the Interchange Apocalypse
it turns out injury accidents at these locations have seen a sixty percent drop.
The study of traffic and mass transportation systems is incredibly complicated.
I just can't explain it all in a YouTube video. The point is that there's no magic bullet to stopping traffic jams
and cities have to do the best with the money they have.
So, the next time you see annoying road construction, just remember that although road improvements
sometimes seem to move at a snail's pace, things are improving.
And a lot of people are working really hard to make sure you arrive at your destination safely.
Also, while I have you here... these are turn signals,
they let other drivers know what you are doing, and you should use them!
... See ya!
Thanks to my patrons. I get contacted a lot by teachers who show my videos in their classrooms...
if there's a topic you would like me to cover, then let me know in the comments below
and I'll pretend to consider it.
Also, if you're really bored, I have linked to a thirty-three-page document about the
Diverging Diamond Interchange by the Missouri Department of Transportation.
But before you do that, share this video with everyone on earth.
And subscribe to my channel... or don't, I don't really care.