September 3rd, 1967. The day Sweden’s roads changed overnight.
Known as Dagen H or H Day Sweden joined its European neighbours by
reversing traffic patterns from driving on the left-hand side of the road to the right.
Soon after was the opening of a major new six-lane motorway in the capital of Stockholm. And today,
It remains the only major thoroughfare in the city.
But with increasing population and congestion, the road has since doubled its initial capacity.
More lanes have been added but it’s not enough. And residents are starting to notice.
So officials looked for another solution. Enter the Stockholm Bypass. A $4BN road
and tunnel system that will go around the entire city. When it completes,
it will be one of the longest road tunnels in the world.
Of course, building under all of Stockholm's famous waterways and islands is no easy task.
But as more and more people move here, the race is on to dig itself out of this dilemma.
Stockholm, Sweden. A city of 14 islands, cold winters, and the home country of IKEA and ABBA.
Thanks to strong economic prosperity, it’s one of the fastest growing cities in all of Europe.
By 2100, the population is expected to swell over 43% to nearly 3.5M.
Of course, more people means more traffic. While Stockholm
does have an extensive public transit network - driving is still the most
popular form of transport. And the roadways are starting to take a hit.
So Stockholm is building the E4 Bypass to ease congestion on its existing roadway.
Here’s what it will look like.
Starting south of the city in Skärholmen the 21km system - which includes a massive 18 km tunnel -
will link up around to the north in Häggvik - diverting traffic westward of the city centre.
A twin set of tunnel tubes will carry three lanes of traffic each,
along with six interchanges which will connect existing roads,
and two roundabouts. At its deepest point, the route will reach nearly 100m below ground level.
When it completes in 2030, the $4BN project will
be one of the longest road tunnel systems in the world.
This enormous project isn’t built in a day. It requires incredible technical skill and
knowledge in the field of engineering. Curious about what it takes to gain these skills,
or want a glimpse at some of the complex math behind the world’s longest road tunnel system?
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Now, let’s get back to the one of the world’s longest road tunnel systems…
And you only have to look at a map of Stockholm
to realise why constructing this route is so complicated.
Digging a tunnel under land is one thing … but weaving in and out of
waterways and deep underground presents entirely new challenges.
To clear the route, workers began by drilling a ring of holes into
the rock. These are injected with a mixture of cement and water,
so that once hardened water can’t seep in through any natural cracks.
Then, more holes are drilled and filled with blasting material. Piece by piece,
the rocks are exploded away and scraped out, as the tunnel begins to take shape.
It will take years to just excavate the 22 million
tonnes of rock and sand needed to make way for the tunnels.
After the section is carved out, workers reinforce the tube with rock bolts and
spray the walls with concrete. It’s then clad with an inner wall and outer ceiling
to make doubly sure no water seeps in. But not all of the rock is the same and
different sections of the tunnels presented different challenges.
Some of the weaker rock needed extra reinforcement, while other
parts required more sealing than originally planned. Both of which slowed down progress.
Of course, digging the tunnels is only part of the challenge.
Ensuring drivers’ safety is critically important.
I don’t know about you, but if I am driving that far underground,
I want to know that I will be making it OUT to the other side.
To do this, a ventilation system with 250 reversible jet fans and four exhaust air
stations to maintain air quality. And in the case of vehicle fire, a water-based system will
be built in along the tunnel ceilings in 50 metre long sections throughout.
Now, of course, building a tunnel under a city is more technically complicated than
building a traditional road through it. But tunnelling will help reduce
the project’s impact on the environment and maintain more space for housing above ground.
Now, this all sounds like a lot of work to construct new infrastructure for cars at a
time when people are being encouraged to take public transit over driving. Sweden is even
banning petrol and diesel cars from parts of the city in an effort to clean up its air.
That’s all part of its goal of reducing carbon emissions by 30% by 2030.
The government says traffic emissions from the new
bypass, officials estimate it will only contribute less than 1% of CO2 emissions.
But one university research paper found that 1% figure might be understating the impact once you
take into account possible increases in traffic, construction materials and non-electric vehicles
The Stockholm Bypass has been a long awaited project. It was originally
supposed to be finished in 2018. But here we are in 2024. The roadway is still under
construction and it’s not expected to be finished until the end of the decade.
To make matters more complex, the country has blown through its initial $3.3BN budget by nearly
a billion dollars due to contract cancellations, worksite safety issues and politics.
As Stockholm’s population continues to rapidly swell,
it might not have much more time for additional delays. Traffic in the city centre is already
feeling strained, so the completion of the bypass will be a welcome relief.
This is one of the country’s largest ever infrastructure projects, the light at the
end of the tunnel is growing brighter and all eyes are on Sweden to see its success.
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