HISTORY124 - Bridges

The history of bridges has been on my blog ideas list for a long time.  In discussing possible blog subjects recently, noting that I had recently written about Roman aqueduct bridges, Pat suggested that I might want to broaden that topic to the history of all kinds of bridges.

 

After a short introduction, I will identify the six main types of bridges, then discuss the history of bridges from ancient times to today, next notable bridge failures, and finish with some interesting facts about bridges.

As usual, I will include my primary resources at the end.

 

Introduction

The history of bridges is a chronicle of humanity's evolving engineering skills, from simple logs laid across streams to complex structures of iron, steel, and concrete spanning vast distances.

A bridge is a structure carrying a road, railroad, path, or canal across a river, lake, railroad, road, ravine, or other obstacle.  It is constructed for the purpose of providing passage over an obstacle, which is otherwise difficult or impossible to cross.  Its primary function is to transport vehicles, trains, and pedestrians, but bridges may also accommodate pipelines, buildings, wildlife, and canals. 

The design of a bridge must satisfy many requirements, such as connecting to a transportation network, giving adequate clearances, and providing safe transport for its users.  Additional factors include cost, aesthetics, and longevity.  A bridge must be strong enough to support the weight of the bridge itself, as well as the traffic passing over the bridge.  It must also tolerate stresses imposed by the environment, such as wind, snow, earthquakes, water currents, flooding, and temperature fluctuations. 

 

Types of Bridges

Designs of bridges vary depending on factors such as the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, the material used to make it, and the funds available to build it.  The six main types of bridges are shown below:

The six main types of bridges.

Here is a description of each of these bridge types in their modern form:

Beam Bridges. The simplest and oldest bridge design, consisting of a horizontal beam supported at each end by a pier or abutment.  Weight on the deck is pushed straight down onto the supports.  Typically used for short spans, like highway overpasses or pedestrian walkways.  Modern beam bridges often use prestressed concrete, which is concrete strengthened with steel bars (rebar).  This makes the bridge strong against both pushing and pulling forces.

Arch Bridges. An arch bridge has a curved, arch-shaped structure with abutments at each end.  It is under constant compression, with forces pushing the weight outward along the curve to the abutments.  This makes it very stable.  Suitable for longer spans than beam bridges and can be built higher to allow for boat traffic.  Stone, brick, and other materials that are very strong when pushed (in compression) are used for arch bridges.

Truss Bridges. A truss bridge uses a framework of interconnected triangles, known as a trusses, to support the roadway. The truss can be built above, below, or on the sides of the deck.  The triangular units distribute the load, or force, from a single point over a wider area, creating a rigid structure with a high strength-to-weight ratio.  Effective for carrying heavy loads over medium-to-long distances, such as railway bridges.  The triangular parts of truss bridges are made from straight bars, usually of steel.

Suspension Bridges.  The deck hangs from vertical suspender cables, which in turn connect to two or more main cables that are suspended between towers and anchored at each end.  The load from the deck is transferred by the vertical suspenders to the main cables, which then distribute the weight to the towers and anchorages.  Ideal for the longest spans, often over 3,000 feet.  The main cables are usually made of steel cables, often coated with zinc to prevent rust.  Most of the bridge structure is also steel, but some parts might use steel-reinforced concrete.

Cantilever Bridges. A cantilever is a rigid structural element, like a beam, supported at only one end.  Cantilever bridges are built outwards from each support, with spans meeting in the middle.  Supported by counterbalanced beams that extend from the central pillar, often reinforced with trusses.  Built for spans that are too long for simple beam bridges but not long enough for the most massive suspension bridges.  Smaller bridges might use simple beams.  Large cantilever bridges for cars or trains use strong structural steel frames or concrete box girders structural beams in the shape of a hollow box).

Cable-Stayed Bridges. The bridge deck is supported by cables that run directly from the roadway up to one or more towers.  The cables transfer the bridge's weight directly to the towers, which carry the load down to the foundation.  Unlike suspension bridges, they do not require large ground anchorages.  Optimal for medium-to-long span lengths, generally falling between the lengths suitable for cantilever and suspension bridges.  Cable-stayed bridges primarily use steel and reinforced or prestressed concrete for their main components like the towers, deck, and foundations.  High-strength steel cables are used for the stay cables, though some modern designs may incorporate carbon fiber-reinforced polymers or other composites for the cables.  The specific materials are often a combination, such as composite decks made of steel and concrete.  

Less common types of bridges are movable bridges, double deck bridges, pontoon bridges, and military bridges.  They may also be categorized by their materials, which include wood, brick, stone, iron, steel, and concrete.

 

History of Bridges

The history of bridges reflects the evolution of humankind's engineering technologies. The ancient Romans and Chinese built major bridges of stone and timber.  During the Renaissance, advances in science and engineering led to wider bridge spans and more elegant designs.  Concrete was perfected in the early 1800s, and proved to be superior to stone in many regards.  With the Industrial Revolution came mass-produced steel, which revolutionized bridge design and enabled the creation of suspension and cable-stayed bridges that spanned wide obstacles.

Antiquity.  The earliest forms of bridges were wooden logs or boardwalks for crossing creeks and swamps.  Bridges made of wooden planks, supported on stone piers were the next evolution of bridges (earliest beam type).  Bridges constructed by progressively overlapping stone layers were used in early civilizations, but were limited to short spans.

For valleys and other wider channels - especially in East Asia and South America, ropes made of various grasses and vines tied together were hung in suspension for single-file crossing.

The ancient Romans were the greatest bridge builders of antiquity, constructing large, permanent structures for their extensive road systems and to carry water long distances on aqueducts.  Roman engineers perfected the circular arch, allowing them to construct longer and more durable stone bridges.  The Romans were also the first to use concrete in bridge building.  They developed a waterproof cement, which was used for foundations and piers, allowing them to build in rivers with soft riverbeds.  Because of these sophisticated techniques; many of their bridges are still standing today.  (See my blogs on Roman roads and aqueducts.)

The Roman Pont du Gard aqueduct was built in southern France in the first century AD to carry water over 31 miles to the Roman colony of Nîmes.

Middle Ages to Renaissance. After the fall of the Roman Empire, much of the knowledge of stone bridge building was lost in Europe, but it was revived during the 11^th to 14^th centuries.  Early bridges in this period were often made of wood and were not durable.  However, the use of stone and mortar was re-established by the 12^th century.

Middle Ages bridges were often sites of commerce and religion, with shops, houses, and chapels built on them.  They were also frequently fortified with towers and ramparts.  Some featured a drawbridge.  The most famous bridge of that age was Old London Bridge, completed in 1209, and soon held a jumble of houses and shops. The uneven quality of construction resulted in a frequent need for repair, but the bridge survived more than 600 years before being replaced.

 Old London Bridge completed in 1209, with the 4-story Nonsuch House added in 157

In 15^th to 17^th century Europe, the Renaissance brought a new emphasis on science and engineering that applied a rigorous, analytic approach to architecture and building.  Bridges had structurally advanced designs, including segmented arches, a type of masonry arch with a circular arc of less than 180 degrees, meaning it has a shallower curve than a traditional round arch.  Flatter arches enabled longer spans, fewer piers, and required less material.  

Florence's Ponte Santa Trinita segmented arch bridge completed in 1569.

Industrial Revolution. The Industrial Revolution of the 18^th and 19^th centuries introduced new materials and scientific approaches that revolutionized bridge construction. 

Cast iron became an important construction material for bridges.  In 1779, the Iron Bridge across the River Severn in England became the world's first major bridge constructed entirely of cast iron, marking the birth of the Industrial Age in bridge building.

The first major cast iron bridge was constructed in 1779 to cross the Severn River in England.

As technology improved, more ductile wrought iron (iron alloy with a very low carbon content) became preferred over brittle cast iron.  The development of truss systems using interconnected triangular elements allowed for stronger, longer spans, particularly for the heavy loads of railways. 

The first modern cantilever bridge was built over the Main River in Germany in 1867 using wrought iron.   The design, which used two cantilevers projecting from opposite banks that met in the middle, allowed for longer spans without supports in the middle, making it possible to cross wide rivers or deep gorges.

The first cantilever bridge was built of wrought iron in Germany in 1867.

Steel and Concrete Era. The mass production of steel in the late 1800s and the development of modern concrete in the late 19^th and 20^th centuries opened the door for record-breaking bridge spans.  Steel provided a much stronger and lighter material than iron.

The first cantilever bridge was built of wrought iron in Germany in 1867.

Steel allowed the creation of new types of structures, including suspension and cable-stayed bridges.  The first steel suspension bridge was the Brooklyn Bridge, completed in 1883.  It used galvanized steel wire for its cables, which allowed for a much larger main span than earlier bridges. 

The Brooklyn Bridge, the first steel suspension bridge (1883), used galvanized steel wire for cables.

Portland cement, invented in the early 1800s, improved Roman-era concrete.  When combined with steel, it created reinforced and prestressed concrete, an inexpensive and strong material, and replaced stone and masonry as the primary material for bridge foundations. 

Cable-stayed bridges - which use cables as the exclusive means of support - became a popular bridge design following World War II.

New Cooper River cable-stayed bridge (2005) in Charleston, South Carolina.

Contemporary Innovations. Today, bridge engineering continues to advance through new technology and construction methods.  Many modern bridges are equipped with sensors to collect real-time data on their structural behavior, helping engineers monitor for stress, vibration, and deterioration.  Innovations include the use of advanced cementitious materials (substances that, when mixed with water, harden into a solid, durable mass, acting as a binder to hold aggregates together), new seismic-resistant designs, and accelerated bridge construction methods that minimize disruption.  Contemporary bridges also serve many functions beyond human crossings, including wildlife crossings, and supports for utilities and restaurants. 

 

Notable Bridge Failures

Bridge failures and disasters are catastrophic events caused by factors like structural flaws, material fatigue, natural disasters, extreme weather, and collisions with boats, often resulting in loss of life and property damage.  Here are some examples of bridge disasters in the United States:

Francis Scott Key Bridge (2024): Baltimore Island.  Continuous truss road bridge that collapsed after being struck by a container ship, resulting in multiple fatalities and major disruption.  Complete collapse of main span.  6 people killed, 2 injured. 

I-35W Mississippi River Bridge (2007): Design flaw in arch/truss bridge, specifically a too-narrow center support, contributed to the collapse during peak hour traffic. Total bridge failure.  13 people killed, 145 injured. 

Sunshine Skyway Bridge (1980): Near St. Petersburg, Florida.  A freighter collided with the steel cantilever bridge's pier during a storm, causing a large section to collapse into Tampa Bay.  35 people killed, 1 injured.

Tacoma Narrows Bridge (1940): Washington State.  Cable suspension bridge collapsed due to "aeroelastic flutter," a phenomenon where wind caused the bridge to oscillate violently and eventually break apart.  No fatalities or injuries.

Ashtabula River Railroad Bridge (1876): Ohio.  Wrought iron truss bridge failed during a severe winter flood, causing a train to plunge into the river below.  Possible fatigue failure of cast iron elements.  92 people killed, 64 injured.

 

Interesting Facts about Bridges

Here are a few interesting facts about bridges:

1. The Danyang-Kunshan Grand Bridge in China is the longest bridge in the world, with a length of 102.4 miles.   Opened in June 2011, this massive viaduct is part of the Beijing-Shanghai High-Speed Railway system.  It spans a wide variety of terrain, including low-lying plains, rivers, canals, lakes, and rice paddies in the Yangtze River Delta.  A 5.6-mile section crosses the open water of Yangcheng Lake near Suzhou and is supported by approximately 2,000 pillars. 

2. The highest bridge in the world is the Huajiang Grand Canyon Bridge in Guizhou, China, which opened in September 2025.  It stands approximately 2,051 feet above the Beipan River.

3. When building the Golden Gate Bridge, the lead structural engineer insisted on the installation of a safety net even though its $130,000 cost was deemed exorbitant.  Over the four years of its construction, the net saved 19 men, who named themselves the “Halfway to Hell Club.”

Golden Gate Bridge in San Francisco.

4. The five-mile-long Mackinac Bridge (a suspension bridge that connects the Upper and Lower peninsulas of Michigan) has a program that sends a crew member to drive people across if they’re too afraid to drive themselves.  It gets between 1,200 to 1,400 calls every year.

5. The Oresund Bridge, connecting Sweden with Denmark, ends overwater and continues underwater.  (The justification for the additional expenditure and complexity of digging a tunnel for part of the way, was to avoid interfering with air traffic from the nearby Copenhagen Airport, to provide a clear channel for ships in good weather or bad, and to prevent ice floes from blocking the strait.)

The Oresund Bridge connecting Sweden with Denmark.

6. In 1848, to begin construction on the Niagara Falls Suspension Bridge, engineers needed to secure a line across the 800-foot chasm. The lead engineer held a kite-flying contest and eventually paid a local boy $5 for securing the first line over the river.

7. There are no bridges over the Amazon River.

8. On May 26, 2002, a guy showed up to an I-40 bridge collapse southeast of Webbers Falls, Oklahoma and took command of the federal disaster response by impersonating a U.S. Army Captain.  The two-time convicted felon led the response effort for two days before fleeing.

9. Albert Gunton, a London city bus drive, in 1952 found himself driving his route crossing Tower Bridge when the bridge began to rise to allow a ship to pass.  He accelerated and jumped the gap, and was awarded £10 for bravery.

10. A German graffiti artist painted a 250 square meter bridge to make it look like it was made from Legos.

11. Soldiers are required to “route step” (or walk out of step) when crossing bridges because, in 1831, the rhythmic march of British soldiers broke a bridge, throwing soldiers off the bridge.

12. The Verrazano-Narrows Bridge (suspension bridge connecting the boroughs of Staten Island and Brooklyn in New York City) has support towers that are so tall and far apart that, due to the curvature of the earth, are almost two inches farther apart at the top than the bottom.

13. The Lake Pontchartrain Causeway in Louisiana, the longest continuous bridge passing over water, is so long that for 8 of its 24 miles, you can’t see land in any direction.

The Lake Pontchartrain Causeway in Louisiana.

14. One of the earliest weapons of mass destruction was used during the Siege of Antwerp in 1585.  A Dutch explosive fire ship containing 4 tons of explosive rammed a fortified Spanish bridge, killing 800 Spaniards, causing a small tsunami, and vibrating windows 22 miles away.

15. The original London bridge is now located in Lake Havasu City, Arizona.

The original London Bridge.

16. There is a bridge in North Carolina with a clearance of 11’8″ that has destroyed dozens of trucks trying to pass under it.

17. The Golden Gate Bridge in San Francisco was not originally going to be painted orange.  The orange color was only supposed to be for a sealant, and was to be painted with black and yellow stripes to ensure visibility by passing ships.  The orange color worked better for fog so it was kept instead. 

18. On May 2, 1845, a bridge in Great Yarmouth, England, collapsed when thousands gathered on it to watch a clown travel down the river in a tub pulled by geese. 400 people went into the river, 79 died, 59 of which were children.

19. After the opening of the New York’s Brooklyn Bridge, a rumor came about that the Bridge was unstable and was going to collapse.  To prove it was safe, P.T. Barnum led 21 elephants across it on May 17, 1884.

20. Around 11% of U.S. highway bridges are considered structurally deficient.

21. There’s a “barrier transfer machine” on the Golden Gate Bridge that shifts medians from one lane to another to increase traffic flow in either direction.

22. George C. Parker, a con man, would sell the Brooklyn Bridge twice a week to tourists; the buyers would sometimes try to put up toll barriers.

23. There is a water bridge across the river Elbe in Germany, it is 1 kilometer long, 34 meters wide, and allows cargo ships to cross the river.

24. There are hidden wine cellars beneath the expanse of the Brooklyn Bridge.  Though no longer in use, they were created to help supplement the building costs as merchants would pay to store expensive bottles in the always cool vaults.

 

We build too many walls and not enough bridges - Isaac Newton

 

Sources

My principal sources include: “Bridge,” “History of Bridges,” and “List of Bridge Failures,” Wikipedia.com; “7 Types pf Bridges Every Engineer Should Know About,” blog.enerpac.com; “The History of Bridge Design,” Brittanica.com; ”Bridge Facts for Kinds,” kids.kiddle.co/bridge; “40 Interesting Facts About Bridges,” kickassfacts.com; plus, numerous other online sources, including answers to many queries using Google in AI Mode.