Innovative bridge engineering, denmark
The Great belt link - tying a nation together
Tackling tricky aerodynamics paved the way to the world’s longest suspension bridge. The great belt link has united Denmark and moved boundaries within bridge engineering.
If you were to build the longest suspension bridge in the world, what would be the biggest hurdles from an engineering perspective?
Looking closer at the East Bridge which forms part of the Great Belt Link in Denmark, one element looms larger than the rest: The strong winds swirling in from the Atlantic Ocean.
GREAT BELT LINK = TWO BRIDGES, ONE TUNNEL
Sprogø, in the middle of Storebælt (Great Belt), connects the two bridges and the tunnel. As part of the construction work, the island was expanded and is now four times its original size.
A FIXED LINK TO REDUCE TRAVEL TIME
Before we look closer at the challenging wind conditions, let's zoom in on the bigger purpose behind the Great Belt Link.
In the past millennium, people with family, friends, work or other interests at the other side of the Great Belt had to take a ferry or cross it by foot during the icy winters.
Ideas for a fixed link were first discussed in the 1850s, with a view to reducing travel times.
Finally, in 1986 a political agreement was reached and a new law was passed that gave the green light for the project to start.
“Time savings and ticket price savings for customers were the main drivers for the bridge,” explains Lars Fuhr, CTO and Technical Director at Sund & Bælt Holding A/S.
“Before the bridge, when we had the ferries, crossing the Storebaelt took an hour plus waiting time and meant planning ahead. Now, it takes 12 minutes,” Lars Fuhr says.
making travel easier
The Great Belt Link has made travelling around in Denmark much easier. For example, the number of available train seats have gone up from 11,000 to 40,000 per year.
ENTERING NEW Territory WITHIN BRIDGE ENGINEERING
The link across the Great Belt is 18 km long and connects the eastern and western parts of Denmark. It consists of two bridges and a tunnel, and with a main span of 1,624 metres, the East Bridge was designed to have the longest suspension span in the world.
Before the link's construction, it was argued whether such a large-scale infrastructure project was even technically and financially feasible. Not least due to the strong winds.
“We were entering completely new territory within bridge engineering. Nobody had succeeded in building a bridge with such a great span. A major issue was how to tame the wind inside the bridge's structure,” explains Allan Larsen, Chief Engineer at COWI.
Before the bridge, when we had the ferries, crossing the Great Belt took an hour, and meant planning ahead. Now, it takes 12 minutes.”
What do a bridge, a flute and a guitar have in common?
Chief Engineer Allan Larsen gives you the answer.
Breaking new ground
The tricky aerodynamics were far from the only technical challenge. Lars Hauge, Senior Vice President at COWI, had only just joined the company as a young engineer when the Great Belt Link project kicked off.
a huge impact on society
In June 1997, the first passenger train rolled through the tunnel under the Great Belt, and the bridge for car traffic opened the following year, in 1998.
The Great Belt connection is one of the world's largest bridge and tunnel constructions, and the connection has had a tremendous impact on the millions of Danes who use it.
“The link has increased growth and mobility. One example is that lorry traffic has more than doubled, ensuring flexible distribution. Companies within the industry have also benefitted greatly from knowledge gains in tunnel and bridge engineering by contributing to the construction. Today, several of them, including COWI, are industry leaders in bridge and tunnel design and construction,” says Lars Fuhr.
Lorry traffic has more than doubled ensuring flexible distribution.
The ferries transported around 8,000 cars across the Belt per day. Now, more than 35,000 cars use the link every day, making it a key element in connecting Denmark’s different regions.
An analysis, published by the Ministry of Transport and Sund & Bælt, shows that over the course of 50 years the Great Belt Link will give Danish society a gain of DKK 379 billion, equivalent to an annual gain of DKK 9 billion.
The gains come from benefits like less time spent crossing the Great Belt and reduced costs and more flexibility when doing business across the different regions.
Take a ride with the Rope Access TEam
COWI is responsible for maintenance of the Great Belt Bridge. Most of the inspection work is now handled by drones, whereas repairs are still in the hands of humans. Join the Rope Access Team at the top of the bridge, where they inspect it for cracks, hollows or corrosion in the concrete.
Facts about the Great Belt Link
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The East Bridge was designed to have the longest suspension bridge span in the world, but was eventually surpassed by the Akashi Kaikyō Bridge in Japan and the Xihoumen Bridge in China. Today, the East Bridge has the world's third-longest suspension bridge span.
- At 8,024 m long the East Tunnel for trains is Europe's third-longest bored tunnel.
- Environmental considerations affected the choice of alignment and determination of the design. In 1997, a report concluded that the marine environment was at least as good as before construction work began.
- There have been significant savings in energy consumption by switching from ferries to the fixed link. In terms the total carbon footprint, including the carbon used during construction, the bridge was carbon-neutral after seven years of operation compared to the ferries.
- A breakdown of the total number of driving trips shows that motorists with private errands, including commuting, account for approx. 78%, while just under 1/4 of trips are for business purposes.
- Today, the ticket price is half the cost of the ferry ticket from 1998 (adjusted in line with the consumer price index).
Report from Sund & Bælt Holding (only in Danish): http://bit.ly/2CboH4Q
The east bridge
COWI's services on the east bridge
- Conceptual design
- Tender evaluation assistance
- Tender design
- Detailed design
- General supervision during construction
- Inspection and maintenance of steel structures, equipment and mechanical installations
- Implementation of IT management systemmanagement system
PROJECT DETAILS
LOCATION:
Denmark
PERIOD:
1986-1998
CLIENT:
A/S Storebæltsforbindelsen (subsidiary to Sund & Bælt Holding A/S)
Get in contact
Lars Hauge
Regional Vice President
Bridge, Tunnel and Marine Structures, Denmark
Tel:
+45 56402881
lhe@cowi.com