I used to think driving getting more and more dangerous
and one reason is the media loves to sensationalize car accidents
Multi-car pileup in North Texas has killed at least six people
Incredible!
And with those kinds of stories
I was surprised by how the fatality rate
has steeply dropped over the decades
even with more drivers today on our roads today
We save more lives because of better seat belts enforcement
and catching intoxicated drivers
Cars are also safer with crumple zones,
Airbags
and ABS brakes
But did you know we've greatly improved the design
and engineering of road barriers in the last 60 years?
Like this connection between a guardrail and concrete barrier
In the past vehicles used to be crushed
but now they gracefully bounce off
and I’ll tell you why later
We also removed these terminals from highways
which in the 60s made you look like a hot dog
and replaced them with something far safer
My name is Andrew
and let's uncover how good road barriers have gotten
to save more lives
Roadside safety equipment is made by different companies
and their products undergo real-life crash tests
to prove their products work
In the United States
that standard has gotten more rigorous over time
and the latest is MASH
or the Manual for Assessing Safety hardware
Compared to the older 1998 standard
MASH uses heavier vehicles
faster speeds
and higher angles.
MASH-rated equipment has to be built better
to handle the much higher impact forces
Europe uses a different standard,
EN 1317
but the safety principles are similar
In this video
I'll be focusing on MASH
and how it's made our roads safer
MASH-rated products have six safety ratings
the lowest is TL1 with higher ratings requiring
products to stop heavier vehicles at faster speeds
The highest TL6 barriers that can stop tanker trucks
are massive structures and rarely used on our roads today
For each level, all equipment has to pass three tests
Number 1
It must keep the vehicle upright with no rollovers
which can cause severe injury to occupants
which means this product would fail and would need a redesign
Number 2
The vehicle can't tip more than 75 degrees
or go over the barrier
that means this barrier does not pass MASH testing
Number 3
There can be no penetration
or crushing of the passenger compartment
and impact forces must be
below the maximum allowed
All of this data is recorded and analyzed to
figure out if a product fails or passes
MASH-rated equipment has been mandated
for new installations like this concrete barrier
and is an important part of the safety system
Barriers prevent vehicles from driving into hazards
like buildings
bodies of water
and oncoming traffic
But, crash barriers are themselves a danger
they're longer, closer, and easier to hit
which increases the number of crashes
even though severe injuries and deaths are greatly reduced
It's far better to have vehicles run off the road
into a safe area of land called the clear zone
which allows drivers to recover or reduce the severity of a crash
Engineers can create clear zones by removing hazards
and grading the land according to guidelines
which covers things like the steepness and the width required
But it might not make financial sense
or it's not possible to create a large enough clear zone
which is when barriers can be used
These barriers come in three categories
concrete, guardrail, and cable
You'll often see concrete walls like this one
While it seems simple
there's some surprisingly well-thought-out engineering
If you look at their profile
many aren't vertical
but sculpted to reduce crash forces
When hit
your vehicle rides up the sloped surface
and this vertical motion dissipates energy
which reduces vehicle damage and impact on occupants
Unfortunately
this lifting motion can cause the vehicle
to roll over under high speeds and impact angles
To improve this engineers tested many shapes
and while the New Jersey barrier is popular,
Single Sloped and F-Shape are better
as they don't lift the vehicle as high
which increases stability and prevents rollovers
In comparison
vertical barriers minimize upwards movement.
They're often used on bridges
as you don't want vehicles to be catapulted over the sides
Unfortunately
that increases the impact forces and wheel damage
which could cause the vehicle to veer sharply into traffic
As well higher lateral forces
can push your head through the window
which can cause head slap
and greatly increase your chance of dying
For those reasons
you'll mainly see sloped barriers on highways today
Concrete walls are often used where you can't have any movement
for example
if it's close to a hazard
When there's more space
you'll often see a semi-rigid system instead
These can use a box-beam or more commonly
you'll see a flat corrugated guardrail connected
to a wooden or metal beam for support
These are driven into the ground
and often use a strong post system which is quite ingenious
When hit the posts rotate outwards and down
transferring kinetic energy through the soil
which reduces impact forces
As well
the rail detaches so it stays at the right height
and in contact with the vehicle
which also helps prevent tearing
On older designs
the rail more likely to remain connected and can rip
letting the vehicle through
This tearing can also happen if the posts
can't easily rotate which pulls down the rail
The new
safer MASH-rated guardrail
only used a minor height increase and
connection change versus the older rail
to better contain heavier vehicles
and prevent taller ones from jumping over the guardrail
It's also likely there's an offset block that
keeps your wheel from snagging
This helps the guardrail improve stability
and reduce sudden impact forces on occupants
Remember this guardrail and concrete connection I mentioned earlier?
Engineers figured out they need to add extra posts
to prevent vehicles from behind crushed
If the connection between the two is not reinforced
the guardrail bends and tears
with the vehicle smashing into the concrete face with horrific outcomes
Engineers added posts to stiffen the connection
and allow the vehicle to bounce off as it was designed
Finally
we have Cable Barriers that are placed in medians
to prevent vehicles from flying across and striking oncoming traffic
These have existed for decades
as you can see in this 1930s Missouri Transportation video
Modern systems use three or four cables to safely catch vehicles
and are under high tension to withstand multiple impacts
and reduce movement
Unlike concrete or guardrail
there's some controversy with cable barriers.
Critics say they're dangerous
and only put in because of the low price
Transportation engineers argue they reduce serious injuries
and can save more lives
Let's look deeper
Cable barriers are several times cheaper than concrete
and 40% cheaper than guardrails
because it uses fewer materials and lighter machinery
which reduces logistics, construction, and product costs
You can also install cable barriers on slopes
which saves money on landscaping
In comparison
concrete barriers can require heavy machinery, a sewage system,
flat ground, troublesome logistics, and more time
The big downside with cable barriers is the greater vehicle penetration
as it's easier to slip between the ropes
This is shown in two studies evaluating over 10000 crashes
which compared concrete, guardrail, and cable systems
From this
people say cable barriers are unsafe
and cause way more deaths
But that's not completely accurate
In fact, these two large studies showed an
equal or slightly higher fatality rate versus concrete
As well
what isn't mentioned enough
is that cable barriers can reduce injuries.
Cable barriers stretch when hit
which decreases injuries due to reduced impact forces
Both studies found a big reduction in total injuries
As well this stretching helps prevent the vehicle from bouncing back into traffic
and causing a second, more dangerous accident
More importantly
the lower price lets you build more cable barriers versus other types
and the added length saves more lives
That's important as we don't live in a world with unlimited money
and there are many construction projects
and many miles of unprotected roadways
I could keep going
but this isn't a video about cable barriers versus the world
Instead, I wanted to show that each barrier has its benefits and drawbacks
To pick the right system engineers weigh factors
like traffic, volume, vehicle types, and landscape
So besides the barrier itself
at both ends you'll often find a protective terminal
like this one
that saves drivers if they run into it
In the 60s, the state-of-the-art was fishtail or spoon designs
that tried to distribute the impact across more of the vehicle
These were widely used decades ago and were awful
Unfortunately this act as a spear when struck head-on
and can result in catastrophic injuries
In the late 60s turn-down ends were used
which bent the rail 45 degrees and buried it in the ground
These prevented spearing
but vehicles could easily vault or roll over
which caused serious injuries or fatalities
In the early 70s various breakaway cable terminals like this one here
were invented to minimize spearing
It works by having the end roll away
with posts breaking off to redirect vehicles into a clear zone
These were used for twenty years
but phased out as they were too stiff for small vehicles
and could still spear occupants
In this test footage
the guardrail smashes into the side of the vehicle
and would dice up any occupants inside
Nowadays we have energy-absorbing terminals
that let people walk away from highway speed crashes.
For example, this is the MSKT
MASH Sequential Kinking Terminal System
and costs around $3000 US Dollars
All terminals including this one have to do two things
protect occupants that hit it head-on and anchor the guardrail
The MSKT when hit head-on
dissipates kinetic energy by crushing and kinking the rail
while shooting it out the side
Its post and anchor are designed to breakaway safely
as the head travels down the guardrail
and slows and controls the vehicle
What I found impressive
is the terminal has to do the exact opposite
and provide tension when the rail is hit
The cable and ground strut keeps the posts and rail
from being pulled down
which is called anchoring
Otherwise
the guardrail releases from the end post
and the vehicle runs into the hazard
Also if hit where the rail isn't strong enough to redirect vehicles
the MSKT safely lets vehicle through which is known as gating
That's not a problem as engineers add a clear zone behind it
While there are other terminals
I'm going to talk one more because it's cool
This is the Trinity Softstop.
When struck head-on
it crushes the guardrail vertically
pulls it through the impact head
and shoots it under the vehicle
You can see how the guardrail slides through the impact head as seen in this assembly video
and what the rail looks like after its been crushed
Not only does this keep the guardrail off the road
improving safety
but it keeps the rail anchored and maintains tension in the system
While the terminals for guardrails were fairly compact
I discovered these larger units are different
They're called crash cushions
and are placed in front of fixed structures such as bridges
toll booths, and concrete barriers
Before crash cushions were created in the 80s
engineers used ramped ends which
produced dramatic and dangerous results
Nowadays we use crash cushions in these
three categories to safely stop vehicles
Starting with sacrificial systems like sand barrels
these slow vehicles down through the transfer of momentum
They're arranged by weight
from lightest to heaviest
so small vehicles can be gently slowed down
and still protect heavier ones
These systems are cheap around $3000 for the parts
but anything hit needs to be replaced
and it's messy to clean up
These are also useful for construction sites
with one model using a metal sled that controls the vehicle
as it crashes through the water-filled cartridges
There's also a mobile version that is mounted to the back of trucks
that are used to protect road crews
Next, we have cushions like this QuadGuard M10
that are better for frequently hit locations
When hit the steel structure collapses but is designed to survive
and can often be reused by pulling it out with a truck
Afterwards
you'll have to replace the cartridges inside
which can cost around $900 each
Larger systems can use six of these
which can get expensive if hit often
For spots with many collisions
engineers use cushions that bounce back
or be easily reset when hit
and requires less time and money to repair
There are many designs
but I found SCI's Smart Cushion particularly interesting
What's neat is the gas cylinder inside
adjusts the stopping force based on weight and speed
so cars and trucks have the right resistance
After an impact
the smart cushion can be quickly reset
by pulling it out and replacing a few bolts
Other systems like Traffix's Compressor
use high-density polyurethane to absorb and bounce back after an impact
While restorable cushions can be double or triple
the price of units that use replaceable cartridges
the repair costs are much lower and with enough crashes
restorable units save money in the long term
This is just one example of how engineers can maximize protection
and justify how your money is spent
That brings us to how governments figure out
how much money is worth spending
to save your life or prevent a serious injury
Those values are called crash costs
and are used to determine if safety improvement projects
are economically justified
Engineers compare costs like adding a barrier
to the benefits like saving your life
to figure out what safety measures should be added
Governments value your life and limbs differently
depending on your location
but the average to save your life in 33 states is
4 million dollars
If you want to learn more
about how these values were calculated and used
I'd recommend you google the podcast
"Lives vs The Economy" by NPR's Planet Money
if you're interested
While it's nice that the government is thrifty at spending your money
imagine being told saving your life isn't cost-effective
That's what happened in my province of Ontario
on a stretch of Highway called "Carnage Alley"
which had no median barriers
After a series of deaths from vehicles
crossing the median and hitting oncoming traffic
local groups like "Build the Barrier" were created
and they lobbied to have the road upgraded with a concrete wall
The Ministry of Transportation MTO disagreed
and as you can imagine people were not happy
The MTO claimed it wasn't worthwhile to make carnage alley safer
because of a lack of traffic on that stretch of the 401
The government's position speaker is appalling
Well with public pressure a cable barrier was installed
and later the government committed to concrete barriers
along the entire stretch
What I learned is that that road safety can be about public perception
as it is with engineers trying to protect as many people as possible
But, I hope with this video
you can appreciate our roads, engineers
and even the government a little more
As to the future of this channel
while I focused on dashcam reviews
I want to do more videos like this one
and reveal the hidden world of how businesses
and governments pick and use products
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consider donating, there’s a link in the description
Would love to hear your comments and thanks for watching