Views: 222 Author: Astin Publish Time: 2025-03-13 Origin: Site
Content Menu
● Introduction to Through Truss Bridges
● The Longest Through Truss Bridges
>> 2. Astoria-Megler Bridge (USA)
>> 3. Francis Scott Key Bridge (USA)
● The Most Famous Through Truss Bridges
>> 3. Sydney Harbour Bridge (Australia)
● Engineering Innovations in Through Truss Bridges
>> Seismic and Environmental Adaptations
● Preservation and Cultural Impact
>> 2. Dashengguan Yangtze River Bridge (China)
● Future of Through Truss Bridges
● FAQs
>> 1. Why are through truss bridges less common today?
>> 2. How do through truss bridges handle wind loads?
>> 3. What is the lifespan of a steel through truss bridge?
>> 4. Can through truss bridges be recycled?
>> 5. Are there wooden through truss bridges still in use?
Through truss bridges are engineering marvels that combine structural efficiency with iconic aesthetics. Characterized by their overhead truss systems framing a passage for traffic, these bridges have played pivotal roles in connecting regions, supporting economies, and showcasing technological advancements. This article explores the longest and most famous through truss bridges globally, their historical significance, engineering innovations, and enduring legacies.
A through truss bridge features truss structures on both sides of the deck, creating a "through" corridor for vehicles, trains, or pedestrians. The triangular arrangement of its members allows forces to be distributed as tension and compression, enabling long spans and heavy load capacities. These bridges became prominent during the Industrial Revolution, particularly for railways, and remain vital today for their adaptability and durability.
Total Length: 960 meters (3,150 feet)
Main Span: 400 meters (1,312 feet)
Year Completed: 1991
Design: Continuous steel through truss
Significance:
- The world's longest continuous through truss bridge, linking Ikitsuki Island to Hirado Island in Nagasaki Prefecture.
- Built to withstand Japan's seismic activity, it incorporates hydraulic dampers in its lower chords to absorb earthquake energy.
- In 2009, engineers discovered a 20 cm crack caused by wind-induced vibrations. The bridge was reinforced with high-tensile steel plates, showcasing adaptive maintenance practices.
Construction Challenges:
- Balancing the need for a lightweight design with seismic resilience.
- Assembly required floating cranes to position 500-ton truss sections over deep waters.
Total Length: 6,545 meters (21,474 feet)
Main Span: 376 meters (1,232 feet)
Year Completed: 1966
Design: Continuous steel through truss
Significance:
- The longest continuous truss bridge in North America, spanning the Columbia River between Oregon and Washington.
- A critical link in U.S. Route 101, supporting over 1.5 million vehicles annually.
- Its zinc-rich coatings combat corrosion from Pacific Ocean salt spray, demonstrating material innovation.
Engineering Feats:
- Prefabricated components were barged 160 km upstream and assembled on-site, reducing construction time.
- The bridge's 46-meter vertical clearance accommodates large cargo ships heading to Portland.
Total Length: 1,200 meters (3,900 feet)
Main Span: 370 meters (1,214 feet)
Year Completed: 1977
Design: Steel through truss with a curved alignment
Role:
- Crosses the Patapsco River in Baltimore, Maryland, serving as a major route for Interstate 695.
- Named after the author of "The Star-Spangled Banner," reflecting its cultural symbolism.
Unique Feature:
- The curved design minimizes land acquisition costs while providing panoramic views of Baltimore Harbor.
Type: Cantilever through truss
Main Span: 549 meters (1,800 feet)
Year Completed: 1917 (after two collapses in 1907 and 1916)
Historical Impact:
- The longest cantilever truss bridge span globally, declared a National Historic Site of Canada.
- The 1907 collapse, which killed 75 workers, stemmed from miscalculations in the weight of new steel alloys. The disaster led to stricter engineering standards worldwide.
Preservation Efforts:
- Regular ultrasonic testing detects micro-cracks in its 82,000-ton steel structure.
- A vital rail corridor, it handles 30 freight trains daily across the St. Lawrence River.
Type: Cantilever through truss
Main Span: 541 meters (1,775 feet)
Year Completed: 1890
UNESCO Recognition:
- A World Heritage Site since 2015, celebrated for pioneering the use of mild steel in large-scale construction.
- Its iconic red oxide paint scheme requires 240,000 liters of paint every 25 years.
Design Innovation:
- Three double-cantilever towers rise 110 meters above the Firth of Forth, supported by 55,000 tons of steel.
- The bridge's redundancy—multiple load paths—ensures stability even if individual members fail.
Type: Arch through truss
Main Span: 503 meters (1,650 feet)
Year Completed: 1932
Cultural Icon:
- Nicknamed "The Coathanger," it combines a steel arch with through truss supports.
- Hosts major events like New Year's Eve fireworks, attracting 1.5 million spectators annually.
Engineering Legacy:
- Construction required 6 million hand-driven rivets and 52,800 tons of steel.
- The arch design eliminated the need for temporary supports during building, a groundbreaking technique in the 1930s.
Type: Continuous through truss
Total Length: 1,859 meters (6,100 feet)
Year Completed: 1966
Location: Spanning the Taunton River in Massachusetts
Notable Features:
- Curved alignment accommodates tidal river navigation.
- Retrofitted in 2019 with fiber-reinforced polymer (FRP) decks to extend its lifespan by 50 years.
1. High-Performance Steel (HPS):
- Used in modern bridges like the Ikitsuki Bridge, HPS 70W steel offers 70,000 psi yield strength, reducing member thickness and weight.
2. Corrosion-Resistant Coatings:
- The Astoria-Megler Bridge's zinc-rich primers and epoxy topcoats combat saltwater exposure, a model for coastal structures.
3. Composite Materials:
- FRP decks in the Braga Bridge cut maintenance costs by 40% compared to traditional concrete.
1. Cantilever Method:
- Pioneered in the Forth and Quebec Bridges, this technique builds outward from piers without temporary supports, ideal for deep-water locations.
2. Modular Assembly:
- The Astoria-Megler Bridge's components were prefabricated and assembled on-site, slashing construction time by 30%.
1. Hydraulic Dampers:
- Japan's Ikitsuki Bridge uses these to dissipate 35% of earthquake energy, preventing resonance.
2. Scour-Resistant Foundations:
- The Francis Scott Key Bridge employs driven piles extending 45 meters into bedrock to resist riverbed erosion.
Predictive Technologies:
- The Forth Bridge uses drones with LiDAR to map corrosion, while the Quebec Bridge employs strain gauges for real-time stress monitoring.
- Community Engagement:
- Sydney's Harbour Bridge Climb attracts 4,000 visitors monthly, funding preservation through tourism revenue.
Trade Corridors:
- The Astoria-Megler Bridge facilitates $20 billion in annual cargo transport between Washington and Oregon.
Symbolic Landmarks:
- The Forth Bridge's image appears on Scottish £20 notes, symbolizing national pride.
Year Completed: 1781
Significance:
- The first major through truss bridge, using cast iron to span the River Severn.
- Inspired 19th-century metal truss designs despite its modest 30-meter span.
Main Span: 336 meters (1,102 feet)
Year Completed: 2011
Role:
- Part of the Beijing-Shanghai High-Speed Railway, handling trains at 300 km/h.
- Features a hybrid truss-arch design for aerodynamic stability.
IoT Sensors:
- Bridges like the Ikitsuki now transmit real-time data to AI systems, predicting fatigue cracks before they form.
Self-Healing Materials:
- Experimental concrete with bacteria that secrete limestone could autonomously repair cracks.
Solar Integration:
- Proposed retrofits to the Sydney Harbour Bridge include photovoltaic panels on walkways, generating 150 MWh annually.
Recycled Steel:
- The EU's “Green Truss Initiative” aims to use 80% recycled steel in new bridges by 2030.
Through truss bridges are testaments to human ingenuity, blending form and function across centuries. From the tragic lessons of the Quebec Bridge to the smart sensors of the Ikitsuki Bridge, these structures evolve with technological and societal needs. As climate change and heavier loads pose new challenges, innovations in materials and monitoring will ensure their continued role as lifelines of global infrastructure.
While efficient, their high material and labor costs make them less economical than cable-stayed or suspension bridges for ultra-long spans. However, they remain popular for specific applications like railways.
Their open framework allows wind to pass through, reducing lateral pressure. Bridges in hurricane zones, like the Ikitsuki, also incorporate aerodynamic truss shapes.
With proper maintenance, they can last over 100 years. The Forth Bridge, built in 1890, is a prime example.
Yes. Steel components are often repurposed. The UK's Iron Bridge was recently disassembled, with 90% of its material reused in new projects.
Few remain due to fire and rot risks. The Sandy Creek Covered Bridge (USA) is a preserved example, now a pedestrian trail.
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