How Much Does It Cost to Build a Bridge?
Bridges are one of the most important parts of modern infrastructure. From small wooden bridges over small rivers to massive suspension bridges that span across entire bays, there is a huge range of sizes and shapes that bridges can take.
If you have ever thought about doing an engineering project, bridges are a great place to begin.
Overall, you can expect to pay an absolute minimum of $3,000 for a simple bridge for personal use. A bridge meant for public pedestrian use will cost at least $250,000 or more.
Alternatively, larger bridges for road traffic can easily cost $10 million or more, depending on the size and materials used. The cost of building a bridge is affected by the choice of materials, bridge size, and bridge layout.
There are several things that factor into the cost of building a bridge. We will talk about costs for the different types of bridges and factors that affect the cost to build a bridge. We will also answer some frequently asked questions about bridge construction costs.
How Much Does it Cost to Build a Bridge?
There are several types of bridges that you can build, so we will consider a few different types.
Personal Bridge
If you own some property and want to install a small bridge for personal use over a creek or some ravine, then you can expect to spend a minimum of $3,000 for a professional, permanent installation.
The simplest kind of bridge is probably a swinging suspension bridge, which consists of four posts with a series of planks hung between them.
You can buy a prefabricated swinging bridge for anywhere between $1,000 to $3,000, though you will likely end up paying closer to the more expensive end of the range once you factor in landscaping and other materials.
Alternatively, you can build your own simple plank bridge for as little as $500 if you use the right materials. For example, many people build bridges using powerline rods and planks.
You can pick up recycled telephone poles for as little as $1-$2 per foot and place down two as the main supports. From there, pressure-treated boards should cost about $5 per plank.
Pedestrian Bridge
Pedestrian bridges are those meant mainly for foot traffic. The range of pedestrian bridges spreads from small walkable bridges in parks to massive boardwalks that support hundreds of people and buildings. The costs for pedestrian bridges vary significantly because of the variance in designs, shapes, and sizes.
As an absolute minimum, you can expect to pay around $250,000 for a pedestrian bridge that can comfortably carry between 10-20 people at once. That cost is split between materials, landscaping costs, labor, and permits.
Another way to estimate the cost of a pedestrian bridge is $2,000-$3,000 per linear foot. So for a 120-foot pedestrian bridge, you will most likely pay between $240,000-$360,000 for construction. This cost will also be dictated by the kinds of materials you choose.
Automobile Bridge
The last kind of bridge is also the most expensive. Bridges for automobiles are made from durable materials like steel and concrete and can easily span hundreds of feet.
A standard auto bridge can easily cost over $5 million and is closer to $10 million on average. A double lane bridge for cars will likely cost a minimum of $50 million to build.
One way to calculate the cost of a highway bridge is $4,000 per linear foot. So for a 4,000-footbridge, you are looking at at least a $4 million price tag. The largest bridges in the world span several thousands of feet and can cost billions to build.
For example, the Oakland Bay Bridge in Oakland, CA, cost an estimated $6.4 billion. The Macau/Hong Kong Bridge cost an estimated $20 billion to construct.
Factors that Affect the Cost to Build a Bridge
Materials
Materials significantly affect a bridge’s overall strength and overall configuration. When it comes to modern bridges, there are three major materials used: wood, metal, and synthetic polymers.
Wood is the classic bridge material and is commonly used for pedestrian bridges and bridges for small cars. Wood is relatively cheap compared to other materials, but it is not as durable and long-lasting. A well-built wooden bridge can last between 25-35 years, assuming normal weather conditions.
Steel and aluminum are two common metals used in modern bridge construction. Large bridges with multiple lanes for cars consist of a steel frame with concrete foundation blocks.
Steel is incredibly strong but is susceptible to rust and corrosion over time. Steel is also heavy and, depending on the size of the bridge, may require heavy machinery to move and assemble.
Concrete is one of the most common materials for bridges that have automobile traffic. Concrete is a good choice because it is easy to form and is resistant to cracking from heat expansion and contraction. The main downsides of concrete are that it is heavy, requires a lot of equipment to set up, and is expensive.
The last major material is synthetics like fiber-reinforced polymers (FRP). FRPs are chosen for their low weight and durability and also have excellent water and corrosion resistance. FRP bridges are often combined with other materials such as concrete and metal to create strong structures. Materials that incorporate FRP can last for over 50 years.
Intended Use
The intended use of your bridge will determine its overall size and the kind of materials you should select. Length is determined by how far the bridge needs to traverse (e.g., does it go over a creek, river, lake, etc.?), whether the bridge will carry foot traffic or automobile traffic, and the presence of handrails or guardrails.
Keep in mind that all bridge configurations must be built according to National AASHTO Standards to ensure safety and engineering integrity. In order to build a bridge according to standards, you may have to make some trade-offs in design, which could affect the cost and amount of materials and labor.
Construction Site
No matter what kind of bridge you want to build, you will probably need to do some work on the construction site before you begin putting the bridge together. Factors like the distance between the top of the bridge and soil, the span of the bridge, the type of soul, and the water level will all affect site development costs.
Local weather also plays a role. For example, a bridge in place that receives a lot of rain may require extra maintenance to maintain soil integrity. Lastly, the kind of soils also matters. If your selected location has tough bedrock, you may have to do some digging to install the support beams.
Associated Costs
Bridges are associated with several miscellaneous costs, especially as the size and scope of the project increase. If you want to make a small bridge for personal foot traffic, you won’t need to do much extra work.
But if you want to make a larger bridge for public transport, then you will likely need to conduct safety and environmental safety tests. You will also have to acquire permits for building in areas that see public foot traffic.
Lastly, if your bridge is a large project, you will have to pay for equipment rentals and labor. Rental prices and labor costs can vary significantly depending on your location and the type of construction site you are working with.
Frequently Asked Questions
How much does it cost to build a bridge?
It depends heavily on the kind of bridge you are building. A small bridge for personal use can cost as little as $3,000 for a prefabricated solution and as little as $500 for a budget DIY solution.
A larger pedestrian bridge will cost at least $250,000 to construct and can cost several millions of dollars. Large highway bridges for cars and trucks easily cost over $10 million to fund and construct.
Can anyone build a bridge?
It depends on the kind of bridge. If you want to make a small bridge for personal use on your property, then yes, anyone can do it with little to no restrictions.
However, if you want to build a bridge that will see public use, you will have to go through an official process to have your bridge design inspected and tested.
How large is the average bridge?
The average single-lane bridge for an automobile is about 14 feet wide. Small bridges for pedestrians can measure as small as 5 feet wide.
Large bridges with multiple lanes for traffic and walking can easily span over 100 feet wide.
What is the cheapest kind of bridge to build?
The cheapest kind of permanent bridge is a simple beam bridge formed by underlying trusses and planks on top. They are simple to create and can be made from recycled materials.
The cheapest kind of prefabricated bridge is a swinging bridge that should cost about $3,000.
Final Words
Bridges are one of the most useful engineering projects in modern society and form an important part of our infrastructure.
However, there is a huge range of bridges ranging from small pedestrian bridges to multi-lane highway bridges. Bridges represent a massive investment and there are several ways you can reduce the overall costs of construction.
