Retaining Walls for Transportation Infrastructure

Designing the Support Behind the Structure

At McClure, we approach retaining wall design with precision and purpose, understanding they are integral to the safety, functionality, and longevity of transportation infrastructure. Our expertise lies in creating designs that stabilize slopes, manage groundwater effectively, and ensure long-term structural durability. By applying advanced geotechnical and structural engineering principles, we provide solutions that adapt to site-specific challenges and withstand the demands of modern transportation systems.

The Role of Retaining Walls in Transportation Engineering

Retaining walls are indispensable in civil and transportation engineering. In bridge and highway construction, they create stable platforms for roadways, ramps, and embankments where natural ground conditions are insufficient. Beyond holding back soil, retaining walls:

• Prevent roadway and structural failure caused by earth movement.
• Control water flow through engineered drainage systems.
• Enable infrastructure to be built in challenging topographies.
• Reduce environmental disruption by limiting grading and excavation.

A well-executed retaining wall design not only preserves structural safety but also enhances aesthetics by blending engineered infrastructure with the surrounding natural or urban environment.

Types of Retaining Walls

Each retaining wall system has unique characteristics, advantages, and limitations depending on site conditions, load requirements, and project objectives. Below are common wall types and their typical applications:

Gravity Walls: Rely on their own mass—typically stone, concrete, or precast modular blocks—to counteract lateral earth pressures.

Applications: Low-height walls along rural roadways, landscaping for transportation corridors, or where ample footprint space allows wider bases.

Cantilever Walls: Typically utilize a reinforced concrete stem and base slab (masonry can be used for the stem on short or lightly loaded walls), with the weight of the soil above the base used to help resist overturning. Efficient for medium to tall walls, particularly where footprint space is limited.

Applications: Urban highways with limited right-of-way, bridge approaches, and interchange embankments.

Counterfort Walls: A variation of cantilever walls, strengthened by thin vertical concrete webs (counterforts) connecting the wall stem to the base slab. These reduce bending stresses and material requirements, making them cost-effective for very tall walls.

Applications: Large highway embankments, bridge abutments in constrained spaces, and airport or rail infrastructure requiring tall, durable wall systems.

Sheet Pile Walls: Typically made of interlocking steel sections driven deep into the ground. Best for areas with soft soils or where excavation depth is limited. Can be fully cantilevered or utilize tiebacks into the retained soil (permanent walls) or internal bracing (cofferdams and temporary shoring) to provide additional lateral capacity.

Applications: Port facilities, riverfront embankments, cofferdams for bridge construction, and temporary shoring in tight urban work zones.

Soldier Pile and Lagging Walls: Constructed by installing vertical steel H-piles at regular intervals, with timber, precast concrete, or steel panels (“lagging”) placed between them as excavation proceeds. These walls provide quick and flexible earth retention, often serving as temporary shoring but adaptable for permanent use with reinforced facing.

Applications: Urban excavations with limited right-of-way, temporary support during bridge or roadway reconstruction, and long-term walls in constrained sites where speed and adaptability are critical.

Anchored Walls: Sheet pile, soldier pile, or cantilever retaining walls reinforced with tieback rods drilled into rock or soil behind the wall. Appropriate for tall walls, slender wall sections, or sites with restricted space at the base.

Applications: Deep cuts along highways, excavation support for bridge abutments, and areas where wall height exceeds the practical limit of gravity or cantilever designs.

Mechanically Stabilized Earth (MSE) / Segmental Retaining Walls (SRW): Consist of precast concrete panels or modular blocks combined with soil reinforcement (metal strips or geosynthetic grids) embedded in compacted backfill. Highly versatile, cost-efficient, and widely used for highway and bridge approaches due to rapid construction and excellent performance.

Applications: Bridge abutments, highway ramps and interchanges, retaining walls along rail corridors, and areas requiring aesthetic architectural treatments.

Tangent, Secant, and Diaphragm Walls: Constructed by drilling or excavating closely spaced shafts or panels.

• Tangent Walls: Overlapping drilled shafts with minimal or no structural connection, often used for temporary shoring.
• Secant Walls: Interlocking reinforced and unreinforced shafts, providing groundwater cutoff and higher strength.
• Diaphragm Walls: Reinforced concrete panels built in slurry trenches, offering high stiffness and durability.

Applications: Deep urban excavations, tunnel portals, cut-and-cover structures, and permanent retaining systems in constrained metropolitan areas.

Gabion Walls: Built from wire mesh baskets filled with stone or rock. Their permeable nature provides excellent drainage, while their flexibility accommodates minor ground movement.

Applications: Streambank protection, erosion control near culverts and waterways, rural highway embankments, and slope stabilization in flood-prone areas.

Crib Walls: Modular frameworks of precast concrete or timber units, filled with granular material. They combine structural interlocking with mass to resist earth pressures.

Applications: Roadway embankments on steep terrain, mining or forestry access roads, and medium-height walls where foundations are shallow.

Selecting the right wall type depends on geotechnical conditions, available space, environmental impacts, load demands, and budget. Our engineers carefully evaluate these factors to design retaining walls that deliver both performance and constructability.

Our Design Process

The McClure design process integrates geotechnical, structural, and environmental considerations to ensure long-lasting performance:

1. Soil Analysis: Working with our geotechnical subconsultant partners, a comprehensive investigation is completed, including borings, laboratory testing, and slope stability modeling, establish the foundation of wall design by determining soil type, density, moisture content, shear strength, and load-bearing properties.
2. Load Calculation: Static and dynamic load combinations are assessed, factoring in lateral earth pressures, surcharge loads from traffic or adjacent structures, hydrostatic forces, seismic effects, and wind loads. These evaluations ensure the wall can safely resist all applied forces.
3. Geometric and Geotechnical Considerations: Our engineers evaluate overall stability and foundation performance through several key checks:

• Overturning: Ensuring the wall resists rotational failure by providing adequate resisting moments.
• Sliding: Designing sufficient base friction, keying, or anchorage to prevent horizontal movement.
• Bearing Capacity: Confirming soil beneath the foundation can safely carry vertical loads without shear failure.
• Settlement: Estimating and limiting both total and differential settlement to prevent cracking or deformation of the wall or adjacent infrastructure.

Geometric parameters such as wall height, base width, batter (tilt), and drainage details are optimized to balance stability, constructability, and cost.

4. Material Selection: Materials are chosen based on structural requirements, durability, aesthetics, and sustainability. Options include cast-in-place reinforced concrete, precast panels, segmental modular blocks, natural stone, steel, or hybrid systems.
5. Structural Design: Using custom design spreadsheets and advanced software, our engineers create detailed models that define wall geometry, reinforcement layout, drainage systems, and load interactions with adjacent structures.
6. Compliance and Constructability: All designs are prepared in accordance with AASHTO LRFD Bridge Design Specifications and applicable state DOT and local standards. Constructability reviews ensure that the selected wall type can be efficiently built under site constraints while minimizing long-term maintenance needs.

Through this process, McClure ensures that each retaining wall design achieves the required safety factors, provides efficient use of materials, and supports infrastructure performance for decades.

Retaining Walls in Bridge and Highway Design

Bridges rely heavily on retaining walls to manage soil and load conditions at their ends. Uses include:

• Abutments: Function as retaining structures while also transferring loads from the bridge superstructure to the foundation. In addition to the bridge superstructure loads, they must resist earth pressures, water infiltration, and frost action. Retaining walls are also often used in front of bridge abutments in conditions where sloped abutment embankments are not feasible due to site constraints.
• Wing Walls: Extend laterally from abutments to retain roadway embankments, ensuring smooth transitions between bridge decks and approach roads.
• Construction: Sheet pile walls, cofferdams, and other temporary structures are utilized to retain soil from the excavations that are necessary for construction of bridge foundation elements.

Key design factors include settlement control, load transfer, proper drainage to prevent water buildup, seismic resilience, and architectural treatments that align with the overall bridge aesthetics.

Highway projects often traverse steep terrain and unstable soils, making retaining walls essential. Additional uses for retaining walls in highway projects include:

• Slope Stabilization: Protects highways from erosion, rockfall, and slope failures, especially in mountainous or flood-prone regions.
• Noise Barriers: Dual-purpose walls incorporate acoustic panels to shield nearby communities from traffic noise.

Engineering Challenges and Solutions

Designing and constructing retaining walls involves overcoming a variety of geotechnical, structural, and environmental challenges. At McClure, we anticipate these challenges early in the design process and implement proven solutions that ensure safety, durability, and sustainability.

Soil Erosion and Drainage

• Challenge: Poor drainage or concentrated water flow can wash away backfill, weaken soils, and increase hydrostatic pressures, leading to wall instability or failure.
• Solutions: Incorporating subdrains, weep holes, geocomposites, and properly graded backfill ensures that water is efficiently diverted away from the wall. Surface treatments such as vegetation, riprap, or erosion-control mats provide additional protection against runoff and soil loss.

Seismic Activity

• Challenge: Retaining walls in seismically active regions must resist both static earth pressures and dynamic earthquake forces, which can cause sliding, tilting, or structural cracking.
• Solutions: Flexible wall systems, ductile reinforcement detailing, and soil-structure interaction modeling help walls absorb and dissipate seismic energy. Mechanically stabilized earth (MSE) walls and anchored walls often perform well under seismic loading due to their inherent flexibility.

Bearing Capacity and Settlement

• Challenge: Weak or compressible foundation soils can lead to excessive settlement, tilting, or localized shear failure beneath the wall base.
• Solutions: Geotechnical improvements such as soil replacement, compaction, deep foundations (piles, drilled shafts), or ground improvement techniques (stone columns, grouting) increase soil capacity and reduce settlement risk. Wall geometry is also optimized to distribute loads more evenly.

Sliding and Overturning Forces

• Challenge: Lateral earth pressures and surcharge loads can push walls outward or cause overturning if the resisting forces are inadequate.
• Solutions: Designers incorporate sufficient base width, shear keys, soil reinforcement, and batter (inclination) into the wall geometry. Safety factors are applied to ensure reliable resistance against sliding and overturning under worst-case load conditions.

Environmental Impact

• Challenge: Retaining wall construction can disrupt natural habitats, alter drainage patterns, and require significant material resources.
• Solutions: Sustainable design practices include using recycled or locally sourced materials, limiting grading and excavation, incorporating vegetated wall facings, and designing drainage to protect water quality. Gabions, MSE walls with green facings, and crib walls filled with natural stone can integrate infrastructure with the surrounding environment.

Durability and Material Performance

• Challenge: Exposure to freeze-thaw cycles, deicing chemicals, and groundwater can degrade materials over time.
• Solutions: High-performance concrete mixes, corrosion-resistant reinforcement, protective coatings, and appropriate drainage reduce deterioration. Material selection is tailored to local climate and service life requirements.

Construction Constraints

• Challenge: Urban or highway projects often involve limited right-of-way, restricted work zones, and the need to maintain traffic flow during construction.
• Solutions: Modular systems such as precast MSE panels, soldier pile and lagging walls, or soil nail walls allow for accelerated construction with minimal disruption. Construction sequencing and temporary shoring are carefully planned to maintain safety and project efficiency.

By addressing these engineering challenges with proactive solutions, McClure ensures that retaining walls are not only structurally sound but also cost-effective, constructible, and environmentally responsible.

Where We Make An Impact

Retaining walls are essential for safe, durable transportation systems. McClure engineers solutions that combine structural performance with environmental responsibility. Whether it’s a bridge abutment or a highway slope, our team is ready to deliver retaining wall designs that support your infrastructure for decades to come.

Retaining Walls for Transportation Infrastructure

Designing the Support Behind the Structure

At McClure, we approach retaining wall design with precision and purpose, understanding they are integral to the safety, functionality, and longevity of transportation infrastructure. Our expertise lies in creating designs that stabilize slopes, manage groundwater effectively, and ensure long-term structural durability. By applying advanced geotechnical and structural engineering principles, we provide solutions that adapt to site-specific challenges and withstand the demands of modern transportation systems.

The Role of Retaining Walls in Transportation Engineering

Retaining walls are indispensable in civil and transportation engineering. In bridge and highway construction, they create stable platforms for roadways, ramps, and embankments where natural ground conditions are insufficient. Beyond holding back soil, retaining walls:

• Prevent roadway and structural failure caused by earth movement.
• Control water flow through engineered drainage systems.
• Enable infrastructure to be built in challenging topographies.
• Reduce environmental disruption by limiting grading and excavation.

A well-executed retaining wall design not only preserves structural safety but also enhances aesthetics by blending engineered infrastructure with the surrounding natural or urban environment.

Types of Retaining Walls

Each retaining wall system has unique characteristics, advantages, and limitations depending on site conditions, load requirements, and project objectives. Below are common wall types and their typical applications:

Gravity Walls: Rely on their own mass—typically stone, concrete, or precast modular blocks—to counteract lateral earth pressures.

Applications: Low-height walls along rural roadways, landscaping for transportation corridors, or where ample footprint space allows wider bases.

Cantilever Walls: Typically utilize a reinforced concrete stem and base slab (masonry can be used for the stem on short or lightly loaded walls), with the weight of the soil above the base used to help resist overturning. Efficient for medium to tall walls, particularly where footprint space is limited.

Applications: Urban highways with limited right-of-way, bridge approaches, and interchange embankments.

Counterfort Walls: A variation of cantilever walls, strengthened by thin vertical concrete webs (counterforts) connecting the wall stem to the base slab. These reduce bending stresses and material requirements, making them cost-effective for very tall walls.

Applications: Large highway embankments, bridge abutments in constrained spaces, and airport or rail infrastructure requiring tall, durable wall systems.

Sheet Pile Walls: Typically made of interlocking steel sections driven deep into the ground. Best for areas with soft soils or where excavation depth is limited. Can be fully cantilevered or utilize tiebacks into the retained soil (permanent walls) or internal bracing (cofferdams and temporary shoring) to provide additional lateral capacity.

Applications: Port facilities, riverfront embankments, cofferdams for bridge construction, and temporary shoring in tight urban work zones.

Soldier Pile and Lagging Walls: Constructed by installing vertical steel H-piles at regular intervals, with timber, precast concrete, or steel panels (“lagging”) placed between them as excavation proceeds. These walls provide quick and flexible earth retention, often serving as temporary shoring but adaptable for permanent use with reinforced facing.

Applications: Urban excavations with limited right-of-way, temporary support during bridge or roadway reconstruction, and long-term walls in constrained sites where speed and adaptability are critical.

Anchored Walls: Sheet pile, soldier pile, or cantilever retaining walls reinforced with tieback rods drilled into rock or soil behind the wall. Appropriate for tall walls, slender wall sections, or sites with restricted space at the base.

Applications: Deep cuts along highways, excavation support for bridge abutments, and areas where wall height exceeds the practical limit of gravity or cantilever designs.

Mechanically Stabilized Earth (MSE) / Segmental Retaining Walls (SRW): Consist of precast concrete panels or modular blocks combined with soil reinforcement (metal strips or geosynthetic grids) embedded in compacted backfill. Highly versatile, cost-efficient, and widely used for highway and bridge approaches due to rapid construction and excellent performance.

Applications: Bridge abutments, highway ramps and interchanges, retaining walls along rail corridors, and areas requiring aesthetic architectural treatments.

Tangent, Secant, and Diaphragm Walls: Constructed by drilling or excavating closely spaced shafts or panels.

• Tangent Walls: Overlapping drilled shafts with minimal or no structural connection, often used for temporary shoring.
• Secant Walls: Interlocking reinforced and unreinforced shafts, providing groundwater cutoff and higher strength.
• Diaphragm Walls: Reinforced concrete panels built in slurry trenches, offering high stiffness and durability.

Applications: Deep urban excavations, tunnel portals, cut-and-cover structures, and permanent retaining systems in constrained metropolitan areas.

Gabion Walls: Built from wire mesh baskets filled with stone or rock. Their permeable nature provides excellent drainage, while their flexibility accommodates minor ground movement.

Applications: Streambank protection, erosion control near culverts and waterways, rural highway embankments, and slope stabilization in flood-prone areas.

Crib Walls: Modular frameworks of precast concrete or timber units, filled with granular material. They combine structural interlocking with mass to resist earth pressures.

Applications: Roadway embankments on steep terrain, mining or forestry access roads, and medium-height walls where foundations are shallow.

Selecting the right wall type depends on geotechnical conditions, available space, environmental impacts, load demands, and budget. Our engineers carefully evaluate these factors to design retaining walls that deliver both performance and constructability.

Our Design Process

The McClure design process integrates geotechnical, structural, and environmental considerations to ensure long-lasting performance:

1. Soil Analysis: Working with our geotechnical subconsultant partners, a comprehensive investigation is completed, including borings, laboratory testing, and slope stability modeling, establish the foundation of wall design by determining soil type, density, moisture content, shear strength, and load-bearing properties.
2. Load Calculation: Static and dynamic load combinations are assessed, factoring in lateral earth pressures, surcharge loads from traffic or adjacent structures, hydrostatic forces, seismic effects, and wind loads. These evaluations ensure the wall can safely resist all applied forces.
3. Geometric and Geotechnical Considerations: Our engineers evaluate overall stability and foundation performance through several key checks:

• Overturning: Ensuring the wall resists rotational failure by providing adequate resisting moments.
• Sliding: Designing sufficient base friction, keying, or anchorage to prevent horizontal movement.
• Bearing Capacity: Confirming soil beneath the foundation can safely carry vertical loads without shear failure.
• Settlement: Estimating and limiting both total and differential settlement to prevent cracking or deformation of the wall or adjacent infrastructure.

Geometric parameters such as wall height, base width, batter (tilt), and drainage details are optimized to balance stability, constructability, and cost.

4. Material Selection: Materials are chosen based on structural requirements, durability, aesthetics, and sustainability. Options include cast-in-place reinforced concrete, precast panels, segmental modular blocks, natural stone, steel, or hybrid systems.
5. Structural Design: Using custom design spreadsheets and advanced software, our engineers create detailed models that define wall geometry, reinforcement layout, drainage systems, and load interactions with adjacent structures.
6. Compliance and Constructability: All designs are prepared in accordance with AASHTO LRFD Bridge Design Specifications and applicable state DOT and local standards. Constructability reviews ensure that the selected wall type can be efficiently built under site constraints while minimizing long-term maintenance needs.

Through this process, McClure ensures that each retaining wall design achieves the required safety factors, provides efficient use of materials, and supports infrastructure performance for decades.

Retaining Walls in Bridge and Highway Design

Bridges rely heavily on retaining walls to manage soil and load conditions at their ends. Uses include:

• Abutments: Function as retaining structures while also transferring loads from the bridge superstructure to the foundation. In addition to the bridge superstructure loads, they must resist earth pressures, water infiltration, and frost action. Retaining walls are also often used in front of bridge abutments in conditions where sloped abutment embankments are not feasible due to site constraints.
• Wing Walls: Extend laterally from abutments to retain roadway embankments, ensuring smooth transitions between bridge decks and approach roads.
• Construction: Sheet pile walls, cofferdams, and other temporary structures are utilized to retain soil from the excavations that are necessary for construction of bridge foundation elements.

Key design factors include settlement control, load transfer, proper drainage to prevent water buildup, seismic resilience, and architectural treatments that align with the overall bridge aesthetics.

Highway projects often traverse steep terrain and unstable soils, making retaining walls essential. Additional uses for retaining walls in highway projects include:

• Slope Stabilization: Protects highways from erosion, rockfall, and slope failures, especially in mountainous or flood-prone regions.
• Noise Barriers: Dual-purpose walls incorporate acoustic panels to shield nearby communities from traffic noise.

Engineering Challenges and Solutions

Designing and constructing retaining walls involves overcoming a variety of geotechnical, structural, and environmental challenges. At McClure, we anticipate these challenges early in the design process and implement proven solutions that ensure safety, durability, and sustainability.

Soil Erosion and Drainage

• Challenge: Poor drainage or concentrated water flow can wash away backfill, weaken soils, and increase hydrostatic pressures, leading to wall instability or failure.
• Solutions: Incorporating subdrains, weep holes, geocomposites, and properly graded backfill ensures that water is efficiently diverted away from the wall. Surface treatments such as vegetation, riprap, or erosion-control mats provide additional protection against runoff and soil loss.

Seismic Activity

• Challenge: Retaining walls in seismically active regions must resist both static earth pressures and dynamic earthquake forces, which can cause sliding, tilting, or structural cracking.
• Solutions: Flexible wall systems, ductile reinforcement detailing, and soil-structure interaction modeling help walls absorb and dissipate seismic energy. Mechanically stabilized earth (MSE) walls and anchored walls often perform well under seismic loading due to their inherent flexibility.

Bearing Capacity and Settlement

• Challenge: Weak or compressible foundation soils can lead to excessive settlement, tilting, or localized shear failure beneath the wall base.
• Solutions: Geotechnical improvements such as soil replacement, compaction, deep foundations (piles, drilled shafts), or ground improvement techniques (stone columns, grouting) increase soil capacity and reduce settlement risk. Wall geometry is also optimized to distribute loads more evenly.

Sliding and Overturning Forces

• Challenge: Lateral earth pressures and surcharge loads can push walls outward or cause overturning if the resisting forces are inadequate.
• Solutions: Designers incorporate sufficient base width, shear keys, soil reinforcement, and batter (inclination) into the wall geometry. Safety factors are applied to ensure reliable resistance against sliding and overturning under worst-case load conditions.

Environmental Impact

• Challenge: Retaining wall construction can disrupt natural habitats, alter drainage patterns, and require significant material resources.
• Solutions: Sustainable design practices include using recycled or locally sourced materials, limiting grading and excavation, incorporating vegetated wall facings, and designing drainage to protect water quality. Gabions, MSE walls with green facings, and crib walls filled with natural stone can integrate infrastructure with the surrounding environment.

Durability and Material Performance

• Challenge: Exposure to freeze-thaw cycles, deicing chemicals, and groundwater can degrade materials over time.
• Solutions: High-performance concrete mixes, corrosion-resistant reinforcement, protective coatings, and appropriate drainage reduce deterioration. Material selection is tailored to local climate and service life requirements.

Construction Constraints

• Challenge: Urban or highway projects often involve limited right-of-way, restricted work zones, and the need to maintain traffic flow during construction.
• Solutions: Modular systems such as precast MSE panels, soldier pile and lagging walls, or soil nail walls allow for accelerated construction with minimal disruption. Construction sequencing and temporary shoring are carefully planned to maintain safety and project efficiency.

By addressing these engineering challenges with proactive solutions, McClure ensures that retaining walls are not only structurally sound but also cost-effective, constructible, and environmentally responsible.

WHERE WE MAKE AN IMPACT