Bridge Foundation Installation & Construction

What are Bridge Foundations?

The bridge foundations utilize various types of deep foundation applications to support roads and bridges. The foundation’s purpose is to provide stability, maintain the structural stability of the entire bridge, and safely carry the load that will pass over the bridge. Also, the foundation, when chosen correctly and installed with precision, can extend the lifespan of the bridge.

Determined by the project location variables, specific bridge types provide the greatest stability, load bearing and safety of the bridge. Our engineers will determine which of the three foundation types to use after a site inspection depending on the landscape, nearby waterways, slope of the land, ground type, rock depth, and ground resistance.

There are three typical types of bridge foundations:

Pile Foundations
Spread Footing on Rock
Drill Shaft Foundation

What are the various types of Bridge Foundations and Benefits of each?

I. PILE INSTALLATION

Pile installation is a foundation which consists of long, slender shapes that are driven deep into the ground. The piles can be made of steel H-shape, steel pipe or concrete, and can extend several hundred feet into the ground based on the bridge load and soil conditions. Pile installation can be used if there is a minimum of ten feet of dirt over rock so there is ground capacity to drive the pile.

The piles are installed by large machinery that essentially ‘hammer’ the length of pile deep into the ground, doing so repeatedly until they reach a predetermined depth. Various equipment can be used to install the piles. An excavator mounted or crane suspended vibratory hammer can be used, which as per the name, uses vibration to drive piles into the ground. A diesel impact hammer is another option to drive the piles, and is the most predominantly utilized option in our area. Diesel Impact hammer drivers are typically preferred over vibrating hammers to ensure load capacity.

There are three types of piles that can be used:

H-Pile: H-Pile are “H’ shaped steel beams that are driven into ground, through dirt and weathered/soft rock layers, for a deep foundation application. H-piles are as wide as they are deep, offer better weight distribution over a wider area and can support heavier structures. They can be designed for skin friction, but they are most effective at transferring load through pile to tip.
Pipe Pile: Pipe piles are steel pipes that are either welded, spiral-welded or seamless used for deep, underground soil layers, that resist load pressure and allow for point bearing and skin friction. Pipe piles are typically utilized as “friction” piles, which utilized the friction of the pile in the soil rather for capacity than being driven to rock, but can be driven to rock as well. There are applications where a conical point or end cap can be used to increase the drivability and/or load bearing capacity.
Concrete Pile: Concrete piles are precast determined by length and girth needed, made with high-resistant concrete on rigid welded reinforcing cages for increased strength. Concrete piles are predominantly used as friction piles where rock is too deep to reach with H-Piles. While these piles are an option, they have become less common due to the weight and size of equipment required to handle them vs. pipe piles.

II. SPREAD FOOTING ON ROCK FOUNDATION

Spread footing is a process where excavation takes place into competent rock to create a large surface area so a reinforced concrete footing can be poured to support the structure. Essentially, like a snowshoe does not sink into the snow, the spread footing foundation has a wider bottom that “spreads” the weight of the structure over a larger area for greater stability. It is constructed using a concrete stem (a vertical and solid section) and then the concrete spread which distributes the load evenly over a large area.

The size of the spread is based on the load over the surface area, which is dependent on the bearing capacity of the rock strata. The spread can be as small as a 10’ x 10’ square or as large as a 40’ x 40’ square. One benefit of spread footing is that it’s typically the cheapest and simplest option when bedrock is shallow. Why?

It does not require specialized training or expertise, as it’s a less complicated installation process.
It does not require specialty equipment, as common earth-moving equipment is all that is needed to install and set the footing.
Less labor and man hours are needed to install.

III. DRILL SHAFT FOUNDATION

Drill shaft foundation is a process that entails drilling through the overburden and into rock, utilizing a shaft which is a concrete column reinforced with a steel casing pipe or cage. The process includes drilling a large diameter hole utilizing steel casing pipe through the overburden, then a slightly smaller diameter rock socket. Once drilling is complete and the shaft is cleaned out, a steel reinforcing cage is placed in the shaft and concrete is poured.

While this process is most costly, dependent on the location variables, engineers would determine this is the best option when the other foundations cannot safely bear the bridge load. Some benefits include:

Drill shaft foundations require minimal excavation,
Typically eliminates the need for temporary shoring.
It can usually be installed rather quickly and in locations where there is limited space to excavate.
Drilled shaft foundations have very high lateral and axial resistances, low ground vibrations and resistant to scour.

What is the Process of Determining which Foundation to use and of installation?

When determining the installation process and piles used, we complete a site survey to inspect the depth of dirt and rock, nearby waters ways, slope of the land, rate of erosion of the land or any potential scour issues.

*Scour is the engineering term for the erosion of soil surrounding a bridge foundation (piers and abutments). Bridge scour occurs when fast-moving water around a bridge removes sediment from around the bridge foundation, leaving behind scour holes. These holes can seriously compromise the bridge’s integrity.

Cost is always a factor in any project, so when we have the luxury of choosing which type of foundation that would provide the greatest load capacity, stability, and lifespan of the bridge, we will always do our best to reduce project costs.

When determining which foundation type is appropriate for the structure, we consult with Geotechnical Engineers, Structural Engineers, Field Operations and our Safety Team to ensure that we are proposing the best possible option. Some of the factors that are considered in this process are as follows:

Geology of the area;
Depth of rock;
Quality and density of rock;
Project budget and costs involved;
Topography of the area
Nearby waterways or risk of flooding;
Impacts to utilities or adjacent roadways
Safety of our workers and the traveling public

In some cases, a single bridge can have three different foundation types installed on the length of the bridge, depending on the location of each support. The team at Haydon Bridge Company always prioritize the safety, load capacity, quality, and lifespan of the bridge while maintaining the project budget when selecting the foundation type.

Case Studies of Bridge Foundations

Harrod Creek Project (Drill Shaft)

This bridge was included in the East End Crossing Project in Prospect, KY. There was a total of 16 shafts with common shaft sizes of 96” and a rock socket of 90”. Hayes Drilling was the drilling subcontractor for this project.

Johnson Creek Project (Drill Shaft)

This bridge is located on the Mountain Parkway over Johnson Creek. This set of twin bridges had a total of 18 shafts with common shaft size of 60” and a rock socket of 54”. Hayes Drilling was the drilling subcontractor for this project.

P & L Railroad Project (Drill Shaft)

This bridge was built for P&L Railroad located in West Point, KY. This bridge had a total of 20 shafts with a common shaft size of 84” and a rock socket of 78”. Hayes Drilling was the drilling subcontractor for this project.

Russell County Project (Spread Footers)

These spread footers are 22’ x 26’ x 5’-6” thick with a minimum of 1’ embedment into solid rock.

Why Choose Haydon Bridge Company for Bridge Foundation & Installation?

Each of these foundation types have various benefits and are chosen according to the variables presented by the geographical testing and site survey. In business for over 50 years, Haydon Bridge has a great deal of experience and expertise in design/build, various geotechnical conditions, safety planning and construction of each type of these bridge foundations.

We are fluent in understanding site conditions and various geotechnical conditions to choose the appropriate foundation type. We know not only how to determine which foundations is best suited, but with over 50 years and hundreds of bridges and roads in our portfolio, we have the expertise and resources to plan, excavate, drill, install and construct bridges and bridge foundations safely and securely.

We also have the knowledge and experience to pivot when unknown conditions arise. Occasionally unexpected issues arise, or original site surveys were incomplete in their statistics and results. Because we have years of experience in each foundation type, we feel comfortable in choosing option B or C, when we realize A will not provide the best solution.

From the Preconstruction Design Phase to Completion of the Project, we work closely with the design engineers, from the reviewing their plans, determining project objectives, to onsite construction as we keep them informed of all parameters or unexpected variables we encounter and collaborate as a team to keep the project moving forward.

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Haydon Bridge Company

Since 1972, Haydon Bridge Company offers bridge, box culvert and other highway concrete construction in Kentucky, Ohio, Indiana, West Virginia, Virginia and Tennessee.