The World’s 10 Most Expensive Bridges – And What It Takes to Protect Them

Bridges

The world is shrinking. Communication takes place worldwide, in moments. But it’s not just the internet; the speed with which we can move people and goods across the surface of the planet is increasing all the time.

At the heart of this are the world’s new mega bridges, which can take hours, if not days, of travel between distant shores. Allowing nations to expand trade and exert influence – not all of it welcome.

In some ways, these mega-bridges represent the ultimate test of structural engineering. Spanning active seismic zones, freezing oceans and immense physical distances, these structures represent the pinnacle of human ambition. They also represent staggering financial investments.

When a nation spends billions of pounds on a single transport link, waiting for visual signs of structural failure before acting is a critical mistake.

Here are ten of the most expensive bridges ever built – and a look at why preserving our existing infrastructure is the most valuable engineering challenge of the 21st century.

Falling just outside the top 10 most expensive bridges, the very beautiful Samuel De Champlain Bridge, Canada

Falling just outside the top 10 most expensive bridges, the very beautiful Samuel De Champlain Bridge, Canada

#1. Hong Kong–Zhuhai–Macau Bridge, China

Currently holding the record as the longest sea-crossing system in the world and the world’s most expensive bridge, this mammoth took nine years to build. It incorporates three cable-stayed bridges, an undersea tunnel and four artificial islands. Designed to withstand super typhoons and magnitude 8 earthquakes, the immense cost is a testament to the harsh marine environment it spans.

Concrete & Maintenance Challenge

Crossing a harsh marine estuary required a highly specialised concrete mix to resist aggressive chloride ingress and sulphate attack. With a design life of 120 years, maintenance teams must constantly monitor the underwater piles for rust jacking caused by saltwater penetrating the concrete cover.

Estimated Cost£15 billion
Length34 miles (55 km)
LocationPearl River Delta, China [view on map]
Carries6 lanes of road traffic
Architects / EngineersArup
China Communications Construction Company

#2. Danyang–Kunshan Grand Bridge, China

Holding the Guinness World Record for the longest bridge in the world, this viaduct runs roughly parallel to the Yangtze River, traversing lowland rice paddies, canals and lakes. The sheer volume of concrete and steel required to suspend a high-speed railway for over a hundred miles drove the cost into the billions.

Concrete & Maintenance Challenge

Built over soft marshland and lakes, the viaduct relies on hundreds of thousands of precast concrete box girders and deep piles. The primary ongoing challenge is monitoring the massive concrete substructure for differential settlement and managing the dynamic fatigue caused by high-speed trains passing overhead.

Estimated Cost£6.5 billion
Length102.4 miles (164.8 km)
LocationJiangsu Province, China [view on map]
CarriesBeijing–Shanghai High-Speed Railway
Architects / EngineersChina Communications Construction Company

#3. Great Seto Bridge, Japan

Built across the Seto Inland Sea, this is not a single bridge but a complex series of double-deck structures connecting Honshu and Shikoku. The project navigated treacherous underwater currents and complex geological fault lines, resulting in a staggering construction bill when it was completed in 1988.

Concrete & Maintenance Challenge

The massive underwater concrete piers were cast directly into the seabed amidst severe tidal currents. Today, the primary structural threat is the relentless exposure to marine salt spray, requiring continuous non-destructive testing to detect early-stage rebar corrosion before catastrophic spalling occurs.

Estimated Cost£5.5 billion
Length8.1 miles (13.1 km)
LocationSeto Inland Sea, Japan
[view on map]
Carries4 lanes of road traffic, double-track railway
Architects / EngineersHonshu-Shikoku Bridge Authority

#4. San Francisco–Oakland Bay Bridge (Eastern Span), USA

Following the 1989 Loma Prieta earthquake, the original eastern span of the Bay Bridge was deemed seismically unsafe. The replacement project became one of the most expensive public works in Californian history. The new self-anchored suspension bridge features a single massive tower and is engineered to absorb immense kinetic energy during future seismic events.

Concrete & Maintenance Challenge

Sited in a highly active seismic zone, the concrete foundations required intricate internal steel reinforcement matrices to ensure extreme ductility. Maintenance requires intensive structural diagnostics to identify hidden micro-fractures in the concrete shear zones following any seismic activity.

The structural integrity relies heavily on the foundations driven deep into the bay mud. Any sign of foundation settlement requires immediate, precision ground engineering to re-level the massive concrete piers.

Estimated Cost£5 billion
Length2.2 miles (3.5 km)
LocationCalifornia, USA [view on map]
Carries10 lanes of road traffic, pedestrian and cycle path
Architects / EngineersT.Y. Lin International
Moffatt & Nichol

#5. Evergreen Point Floating Bridge, USA

Spanning Lake Washington, this is the longest floating bridge in the world. Because the lakebed is too deep and soft for traditional structural piers, the massive roadway is supported by 77 colossal concrete pontoons anchored to the lake floor with high-tensile steel cables.

Concrete & Maintenance Challenge

Floating directly on the water, the structural integrity of this bridge relies entirely on keeping the concrete perfectly buoyant and watertight. Even microscopic thermal cracking can allow water ingress, meaning continuous scanning and immediate resin injection repairs are a matter of survival rather than standard maintenance.

Estimated Cost£3.5 billion
Length1.4 miles (2.3 km floating section)
LocationSeattle, Washington [view on map]
Carries6 lanes of road traffic, shared-use path
Architects / EngineersWashington State Department of Transportation

#6. Gordie Howe International Bridge

Boasting the longest cable-stayed main span in North America, this monumental border crossing relies on two massive A-frame concrete towers.

Concrete & Maintenance Challenge

The primary engineering challenge is immense wind shear combined with severe freeze-thaw cycles over the Detroit River. The vast concrete decks and cable anchorages will require relentless structural monitoring and the application of highly advanced anti-carbonation coatings to prevent the heavy winter de-icing salts from causing premature reinforcement corrosion.

Estimated Cost£3.3 Billion
Length1.5 miles (2.5 km)
LocationDetroit River, United States / Canada [View on Map]
Carries6 lanes of highway, pedestrian path
Architects / EngineersBridging North America

#7. The Padma Multipurpose Bridge

This two-level steel truss bridge is a geotechnical marvel. Built to connect the southwest of the country to the northern and eastern regions, it completely transforms the local logistics network while traversing one of the most unpredictable waterways on earth.

Concrete & Maintenance Challenge

The Padma River is notorious for extreme river scour, where fast-flowing water rapidly washes away the sediment supporting the bridge piers. To survive, engineers had to drive tubular steel piles up to 120 metres deep. Maintaining this structure requires continuous underwater sonar scanning and the rapid deployment of structural ground anchoring to consolidate shifting soils around the foundations.

Estimated Cost£2.8 Billion
Length3.8 miles (6.1 km)
LocationMunshiganj, Bangladesh – [View on Map]
Carries4 lanes of highway, single-track railway
Architects / EngineersAECOM

#8. The Kerch Bridge, Russia / Crimea

Spanning the Kerch Strait, this pair of parallel bridges – one for road and one for rail – is the longest bridge in Europe. It serves as an extreme modern test case for both bridge construction and preservation under hostile conditions.

Concrete & Maintenance Challenge

Love it or hate it, the fact that the structure has never been permanently out of service – despite ingenious and repeated kinetic attacks – stands as a testament to the phenomenal strength of well-engineered concrete. When marine infrastructure suffers extreme blast loads or lateral shear failure, survival dictates the rapid deployment of emergency structural propping followed by aerospace-grade carbon fibre reinforcement to restore load capacity.

Estimated Cost£2.8 Billion
Length11.9 miles (19 km)
LocationKerch Strait, Russia / Crimea [View on Map]
Carries4 lanes of highway, double-track railway
Architects / EngineersGiprostroymost

#9. Øresund Bridge, Denmark to Sweden

A marvel of integrated engineering, the Øresund connects Copenhagen and Malmö via a multi-modal bridge that seamlessly transitions into an underwater tunnel via an artificial island. This design prevents the bridge towers from interfering with air traffic from nearby Copenhagen Airport while allowing large ships to pass safely above the tunnel section.

Concrete & Maintenance Challenge

The immersed concrete tunnel section demanded absolute watertightness, requiring strict temperature control during the pouring phase to prevent early thermal cracking. Maintenance teams must rigorously combat the effects of aggressive freeze-thaw cycles and de-icing salts during the brutal Scandinavian winters.

Estimated Cost£3.5 billion
Length4.9 miles (7.8 km)
LocationØresund Strait [view on map]
Carries4 lanes of road traffic, double-track railway
Architects / EngineersGeorge K.S. Rotne
Arup

#10. Akashi Kaikyō Bridge, Japan

With a central span of nearly two kilometres, the Pearl Bridge was the longest suspension bridge in the world for over two decades. Construction was incredibly perilous, requiring the massive steel towers to withstand violent typhoons and the harsh, corrosive saltwater environment of the Akashi Strait.

Concrete & Maintenance Challenge

Constructing the colossal anchorages required a bespoke underwater-setting concrete that could be poured 60 metres deep without washing away in the strong currents. Maintaining these massive concrete blocks involves managing immense thermal stress and protecting the outer layers from the highly corrosive marine environment.

Estimated Cost£2.8 billion
Length2.4 miles (3.9 km)
LocationAkashi Strait, Japan [view on map]
Carries6 lanes of road traffic
Architects / EngineersSatoshi Kashima

Honourable Mention: Queensferry Crossing, UK

Falling just outside the global top 10 by cost, this structure remains the longest three-tower, cable-stayed bridge in the world, carrying the M90 motorway across the Firth of Forth alongside two older, historic crossings.

Concrete & Maintenance Challenge

Concrete & Maintenance Challenge

Engineered to last 120 years, the Queensferry Crossing features advanced structural monitoring sensors embedded directly into the concrete. However, sensors only flag the data. Physical maintenance requires specialist engineers to execute targeted concrete rehabilitation to address the inevitable wear and tear caused by heavy Scottish coastal winds and driving rain.

Estimated Cost£1.35 billion
Length1.7 miles (2.7 km)
LocationFirth of Forth, Scotland [view on map]
Carries4 lanes of road traffic
Architects / EngineersDissing+Weitling
Jacobs
Arup

World’s 10 Most Expensive Bridges and The True Cost of Structural Failure

These mega-structures command headlines because of their price tags, but they highlight a universal truth in civil engineering: building new infrastructure is astronomically expensive.

Whether you are managing a £15 billion sea crossing or a vital concrete overpass on the M42, the financial and carbon costs of demolition and replacement are vast. Concrete and steel endure immense daily stress from dynamic vibration, thermal expansion and water ingress. If left unchecked, this leads to rust jacking, delamination and eventual structural failure.

At Structural Repairs, we believe the most sustainable bridge is the one already standing.

We do not wait for concrete to fall. We use advanced non-destructive testing (NDT), Ground Penetrating Radar (GPR) and 3D laser scanning to look deep inside the structural matrix. By diagnosing hidden defects and executing precision structural repairs early, we restore load-bearing capacity and permanently extend the life of vital assets.

Do not wait for structural failure to force your hand. Protect your infrastructure before the damage becomes critical.

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Images courtesy of WikiMedia Commons and Adobe Stock. Masthead image, the Hong Kong–Zhuhai–Macau Bridge at sunset.