As a professional exporter of steel bridge components, we recognize Liberia’s urgent need for durable, efficient infrastructure to support post-conflict economic recovery. Let's explores steel box girder bridges—their design, applications, and advantages—within the framework of AASHTO (American Association of State Highway and Transportation Officials) standards, which govern safety and durability in bridge construction. We analyze Liberia’s specific demand for steel structures, highlight the transformative role of steel box girder bridges in national and regional development (using the completed Monrovia River Crossing Bridge as a case study), and detail tailored surface treatment solutions to address Liberia’s tropical, high-corrosion environment. Our goal is to demonstrate how AASHTO-compliant steel box girder bridges, paired with optimized surface protection, can meet Liberia’s infrastructure needs while delivering long-term value.
Liberia’s infrastructure was severely damaged during its civil wars (1989–2003), leaving critical transport links—especially bridges—obsolete or in disrepair. Today, the country’s economic revival hinges on rebuilding these connections: 90% of Liberia’s trade relies on road transport, and over 60% of major bridges cannot accommodate heavy freight vehicles needed for mining (iron ore) and agricultural exports (rubber, cocoa) (African Development Bank, 2023). Steel box girder bridges have emerged as a preferred solution due to their rapid construction, large-span capability, and adaptability to Liberia’s tropical terrain (rainforests, wide rivers). However, their longevity depends on strict adherence to international standards like AASHTO—particularly for surface treatment, which combats corrosion from Liberia’s high humidity (80–90%), annual rainfall (4,000mm), and salt-laden coastal air. As an exporter with experience in Liberia’s market (e.g., the 2022 Monrovia River Crossing project), we provide insights into how AASHTO-aligned steel box girder bridges can drive sustainable development.
A steel box girder bridge uses steel box girders as its primary load-bearing structure. Fabricated by welding steel plates into a closed, box-like cross-section (typically rectangular or trapezoidal), these girders offer exceptional torsional stiffness and load distribution—critical for withstanding heavy traffic and environmental stress. Unlike truss or beam bridges, the box design minimizes deflection (bending) under load, making it ideal for long spans (100–500 meters) and complex alignments (e.g., highway interchanges, river crossings). Our factory prefabricates girders to precise specifications, ensuring quality control and reducing on-site construction time.
Globally, steel box girder bridges are deployed in scenarios requiring efficiency and durability:
Highway and arterial road crossings: Connecting urban centers to ports (e.g., Monrovia to Buchanan Port in Liberia) and supporting heavy truck traffic.
River and coastal viaducts: Spanning wide waterways (e.g., Liberia’s St. John River) and resisting saltwater corrosion.
Urban infrastructure: Overpasses and flyovers to alleviate traffic congestion (e.g., planned projects in Gbarnga, Liberia’s second-largest city).
In Liberia, their prefabrication is a game-changer: local industrial capacity for on-site steel fabrication is limited, so shipping pre-assembled girders via Monrovia’s port avoids delays and quality risks. For example, our team delivered 12 prefabricated box girders (total steel weight: 1,200 tons) for the Monrovia River Crossing Bridge in 2021, cutting on-site construction from 18 to 9 months.
For Liberia’s context, the advantages are unmatched:
Rapid deployment: Prefabrication reduces on-site work by 30–50% compared to cast-in-place concrete bridges. This was critical for the Monrovia project, which replaced a destroyed concrete bridge and restored daily commutes for 50,000 residents within a year.
Large-span capability: Steel box girders span 100–300 meters without intermediate piers, avoiding disruption to river ecosystems (e.g., Liberia’s Mesurado River, a vital fishing habitat).
Structural efficiency: A high strength-to-weight ratio (2–3x greater than concrete) lowers transportation costs—essential for Liberia’s underdeveloped road network, where heavy concrete components would require specialized haulage.
Durability with proper surface treatment: When coated to AASHTO standards, steel box girders resist corrosion and require less maintenance than concrete, which is prone to spalling (surface cracking) in humid climates.
Developed by the American Association of State Highway and Transportation Officials (AASHTO), the AASHTO LRFD Bridge Design Specifications (Load and Resistance Factor Design) is the global gold standard for bridge safety and durability. Unlike allowable stress design (ASD), LRFD uses probability-based factors to account for variable loads (traffic, wind, seismic activity) and material performance, ensuring bridges meet a 75–100-year service life. For steel structures, key AASHTO standards include:
AASHTO M270: Specifications for structural steel (e.g., A36 or A572 Grade 50, used in our Liberian projects) to ensure strength and ductility.
AASHTO M280: Requirements for surface preparation and coating systems to prevent corrosion.
AASHTO M240: Performance criteria for protective coatings (e.g., epoxy, polyurethane) in harsh environments.
AASHTO is mandatory for:
Projects funded by multilateral agencies (World Bank, African Development Bank), which support 80% of Liberia’s infrastructure rebuild (Liberian Ministry of Public Works, 2023). For example, the $200 million Liberia Road Rehabilitation Project (LRRP) requires all bridges to comply with AASHTO LRFD.
Bridges carrying heavy freight (e.g., mining trucks weighing 80+ tons). AASHTO’s load calculations (e.g., HL-93 design truck) ensure structures can withstand repeated heavy loads without failure.
Coastal or humid regions. AASHTO’s corrosion protection guidelines are tailored to high-moisture environments—critical for Liberia’s Atlantic coastline and rainy seasons.
For our company, AASHTO compliance is non-negotiable: we align our fabrication (e.g., welding to AASHTO AWS D1.5) and surface treatment processes with these standards to qualify for Liberia’s funded projects.
Liberia’s infrastructure gap creates urgent demand for steel bridges:
Post-conflict reconstruction: Over 70% of pre-war bridges were destroyed or rendered unsafe (e.g., the Mesurado River bridge in Monrovia). Temporary crossings (e.g., ferries, bailey bridges) are slow and cannot support freight.
Economic growth: Mining (Liberia’s top export) requires bridges that carry 100-ton ore trucks. Concrete bridges, which take 2–3 years to build, cannot meet the sector’s timeline needs.
Climate resilience: Liberia faces annual floods and tropical storms. Steel’s ductility (ability to bend without breaking) makes it more resilient than concrete, which cracks under flood pressure.
A 2023 survey by the Liberian Ministry of Public Works found that 85% of local governments prioritize steel bridges for their rapid construction and low maintenance costs.
Steel box girders are the top choice for Liberia’s high-priority projects due to:
Span requirements: Liberia’s major rivers (St. John, St.Paul，Mesurado) require spans of 150–250 meters—beyond the capacity of beam or truss bridges.
Urbanization: Monrovia’s population is growing at 4% annually, increasing demand for urban overpasses (e.g., the planned Paynesville-Monrovia Overpass) to reduce traffic.
Cost-effectiveness: While steel has a higher upfront cost than concrete, its 75-year service life (vs. 30–40 years for concrete) lowers lifecycle costs. The Monrovia River Crossing Bridge, for example, is projected to save $1.2 million in maintenance over 20 years compared to a concrete alternative.
Our company supplied prefabricated steel box girders for this $18 million project, funded by the African Development Bank. Key details:
Background: The previous concrete bridge (destroyed in 2003) caused daily traffic jams of 2–3 hours. The project aimed to restore connectivity between central Monrovia and the port.
AASHTO compliance: Designed to AASHTO LRFD (HL-93 load, wind speed 150 km/h), with girders fabricated from A572 Grade 50 steel.
Surface treatment: We applied a three-layer coating system (epoxy zinc-rich primer, epoxy micaceous iron oxide intermediate, aliphatic polyurethane topcoat) to combat coastal corrosion.
Impact: Post-completion, travel time between Monrovia and the port dropped by 40%, and daily truck throughput increased from 150 to 400 vehicles. Local businesses reported a 25% increase in export efficiency within 6 months.
This project demonstrates why steel box girders are now Liberia’s preferred bridge type: they deliver speed, durability, and economic value.
Steel box girder bridges drive Liberia’s growth in three key ways:
Economic integration: Connecting ports to inland mining and agricultural zones reduces transport costs. The planned Buchanan River Crossing Bridge (220m span, our company’s proposal pending) will cut iron ore transport costs by 15%, making Liberian ore more competitive globally.
Regional trade: As part of the Economic Community of West African States (ECOWAS), Liberia needs cross-border bridges (e.g., the proposed Mano River Union Bridge to Côte d’Ivoire). Steel box girders’ large spans and rapid construction align with ECOWAS’s 2030 regional connectivity goals.
Job creation: While girders are prefabricated in our global factories, on-site assembly creates local jobs. The Monrovia project employed 120 local workers (trained by our technical team) in welding, installation, and quality control—supporting Liberia’s goal of reducing youth unemployment (38%, World Bank 2023).
The future for steel box girder bridges in Liberia is robust:
Government planning: The 2023–2030 National Infrastructure Plan identifies 12 priority bridge projects, 8 of which are designated for steel box girders (e.g., Gbarnga-Monrovia Highway Bridge, Harper Coastal Viaduct).
International funding: The World Bank’s 300 million Liberia Infrastructure Resilience Project (LIRP) ear marks 80 million for AASHTO-compliant steel bridges, with a focus on climate-resilient design.
Our company’s role: With our track record in the Monrovia project, we are well-positioned to support these initiatives. We offer end-to-end solutions: AASHTO-aligned fabrication, custom surface treatment for Liberia’s climate, and on-site technical support. We have already submitted bids for the Buchanan and Harper projects, highlighting our ability to deliver girders within 4 months of order—critical for meeting Liberia’s tight timelines.
Liberia’s environment is highly corrosive to steel:
Tropical humidity: 80–90% relative humidity year-round accelerates oxidation (rust).
Coastal salt: Airborne salt from the Atlantic affects bridges within 50km of the coast (e.g., Monrovia, Buchanan).
Rainfall: Annual downpours wash away unprotected steel, while standing water in girder cavities causes localized corrosion.
Without proper surface treatment, steel bridges in Liberia can degrade in 5–10 years. AASHTO standards address this, but successful implementation requires customization to local conditions.
AASHTO M280 and M240 set strict criteria for corrosion protection:
Surface preparation: Abrasive blast cleaning to Sa2.5 (near-white metal) or Sa3 (white metal) to remove all rust, oil, and contaminants. For coastal projects like Monrovia, we use Sa3 (per AASHTO’s recommendation) to eliminate residual corrosion.
Coating systems: AASHTO mandates multi-layer systems for durability. For Liberia, we recommend:
Primer: Zinc-rich epoxy (AASHTO M274), dry film thickness (DFT) 80μm—provides cathodic protection (zinc sacrifices itself to protect steel).
Intermediate coat: Epoxy micaceous iron oxide (AASHTO M281), DFT 120μm—acts as a barrier to moisture and chemicals.
Topcoat: Aliphatic polyurethane (AASHTO M300), DFT 80μm—resists UV degradation (critical for Liberia’s intense sunlight) and provides a durable, easy-to-clean finish.
Quality control: AASHTO requires:
DFT testing (magnetic gauge) to ensure compliance.
Adhesion testing (pull-off strength ≥5 MPa).
Salt spray testing (ASTM B117, 1,000 hours) to validate corrosion resistance.
As exporters, we go beyond AASHTO’s minimums to address Liberia’s unique challenges:
Enhanced DFT: For coastal bridges, we increase total DFT to 280μm (vs. AASHTO’s 240μm) to extend protection. In the Monrovia project, this extra thickness has prevented corrosion for 2+ years.
Pre-fabrication coating: All girders are fully coated in our factory (controlled temperature/humidity) before shipment. On-site touch-up is limited to welds, using the same coating system and supervised by our QC team—avoiding rain-related coating failures common in Liberia.
Cavity protection: Steel box girders have internal cavities prone to moisture buildup. We install drainage holes (per AASHTO) and apply a thick epoxy coating to cavity interiors, preventing hidden corrosion.
Sacrificial anodes: For submerged components (e.g., pier-girder connections), we add zinc sacrificial anodes (AASHTO M294) to provide additional cathodic protection—extending service life by 15–20 years.
Maintenance support: We provide Liberia’s Ministry of Public Works with a 5-year maintenance plan, including annual coating inspections (using our portable DFT gauge) and touch-up kits. This proactive approach ensures long-term performance.
In 2023, a third-party audit (commissioned by the African Development Bank) evaluated the Monrovia Bridge’s surface treatment:
No blistering, peeling, or rust was observed.
DFT remained at 265μm (only 5% loss from the original 280μm).
Salt spray test results (simulating 5 years of coastal exposure) showed no corrosion.
These results confirm that our AASHTO-aligned, customized surface treatment meets Liberia’s needs and delivers on the bridge’s 75-year service life commitment.
Steel box girder bridges, built to AASHTO standards and paired with optimized surface treatment, are a catalyst for Liberia’s infrastructure revival. Their rapid construction, large-span capability, and durability address the country’s post-conflict needs, while their role in connecting economic hubs drives national and regional growth. As an experienced exporter, our company is committed to supporting Liberia’s development: we deliver AASHTO-compliant components, tailor surface treatment to local climatic challenges, and provide end-to-end technical support—proven by the successful Monrovia River Crossing Bridge.
With Liberia’s 2030 infrastructure plan and ongoing international funding, the demand for steel box girder bridges will only grow. We stand ready to partner with the Liberian government, multilateral agencies, and local stakeholders to build bridges that are safe, durable, and inclusive—bridges that not only span rivers but also connect Liberia to a more prosperous future.
African Development Bank. (2023). Liberia Infrastructure Assessment Report. Abidjan, Côte d’Ivoire.
AASHTO. (2020). AASHTO LRFD Bridge Design Specifications (8th ed.). Washington, D.C.: American Association of State Highway and Transportation Officials.
Liberian Ministry of Public Works. (2023). National Infrastructure Plan 2023–2030. Monrovia, Liberia.
World Bank. (2023). Liberia Economic Update: Building Resilience for Inclusive Growth. Washington, D.C.: World Bank Group.
As a professional exporter of steel bridge components, we recognize Liberia’s urgent need for durable, efficient infrastructure to support post-conflict economic recovery. Let's explores steel box girder bridges—their design, applications, and advantages—within the framework of AASHTO (American Association of State Highway and Transportation Officials) standards, which govern safety and durability in bridge construction. We analyze Liberia’s specific demand for steel structures, highlight the transformative role of steel box girder bridges in national and regional development (using the completed Monrovia River Crossing Bridge as a case study), and detail tailored surface treatment solutions to address Liberia’s tropical, high-corrosion environment. Our goal is to demonstrate how AASHTO-compliant steel box girder bridges, paired with optimized surface protection, can meet Liberia’s infrastructure needs while delivering long-term value.
Liberia’s infrastructure was severely damaged during its civil wars (1989–2003), leaving critical transport links—especially bridges—obsolete or in disrepair. Today, the country’s economic revival hinges on rebuilding these connections: 90% of Liberia’s trade relies on road transport, and over 60% of major bridges cannot accommodate heavy freight vehicles needed for mining (iron ore) and agricultural exports (rubber, cocoa) (African Development Bank, 2023). Steel box girder bridges have emerged as a preferred solution due to their rapid construction, large-span capability, and adaptability to Liberia’s tropical terrain (rainforests, wide rivers). However, their longevity depends on strict adherence to international standards like AASHTO—particularly for surface treatment, which combats corrosion from Liberia’s high humidity (80–90%), annual rainfall (4,000mm), and salt-laden coastal air. As an exporter with experience in Liberia’s market (e.g., the 2022 Monrovia River Crossing project), we provide insights into how AASHTO-aligned steel box girder bridges can drive sustainable development.
A steel box girder bridge uses steel box girders as its primary load-bearing structure. Fabricated by welding steel plates into a closed, box-like cross-section (typically rectangular or trapezoidal), these girders offer exceptional torsional stiffness and load distribution—critical for withstanding heavy traffic and environmental stress. Unlike truss or beam bridges, the box design minimizes deflection (bending) under load, making it ideal for long spans (100–500 meters) and complex alignments (e.g., highway interchanges, river crossings). Our factory prefabricates girders to precise specifications, ensuring quality control and reducing on-site construction time.
Globally, steel box girder bridges are deployed in scenarios requiring efficiency and durability:
Highway and arterial road crossings: Connecting urban centers to ports (e.g., Monrovia to Buchanan Port in Liberia) and supporting heavy truck traffic.
River and coastal viaducts: Spanning wide waterways (e.g., Liberia’s St. John River) and resisting saltwater corrosion.
Urban infrastructure: Overpasses and flyovers to alleviate traffic congestion (e.g., planned projects in Gbarnga, Liberia’s second-largest city).
In Liberia, their prefabrication is a game-changer: local industrial capacity for on-site steel fabrication is limited, so shipping pre-assembled girders via Monrovia’s port avoids delays and quality risks. For example, our team delivered 12 prefabricated box girders (total steel weight: 1,200 tons) for the Monrovia River Crossing Bridge in 2021, cutting on-site construction from 18 to 9 months.
For Liberia’s context, the advantages are unmatched:
Rapid deployment: Prefabrication reduces on-site work by 30–50% compared to cast-in-place concrete bridges. This was critical for the Monrovia project, which replaced a destroyed concrete bridge and restored daily commutes for 50,000 residents within a year.
Large-span capability: Steel box girders span 100–300 meters without intermediate piers, avoiding disruption to river ecosystems (e.g., Liberia’s Mesurado River, a vital fishing habitat).
Structural efficiency: A high strength-to-weight ratio (2–3x greater than concrete) lowers transportation costs—essential for Liberia’s underdeveloped road network, where heavy concrete components would require specialized haulage.
Durability with proper surface treatment: When coated to AASHTO standards, steel box girders resist corrosion and require less maintenance than concrete, which is prone to spalling (surface cracking) in humid climates.
Developed by the American Association of State Highway and Transportation Officials (AASHTO), the AASHTO LRFD Bridge Design Specifications (Load and Resistance Factor Design) is the global gold standard for bridge safety and durability. Unlike allowable stress design (ASD), LRFD uses probability-based factors to account for variable loads (traffic, wind, seismic activity) and material performance, ensuring bridges meet a 75–100-year service life. For steel structures, key AASHTO standards include:
AASHTO M270: Specifications for structural steel (e.g., A36 or A572 Grade 50, used in our Liberian projects) to ensure strength and ductility.
AASHTO M280: Requirements for surface preparation and coating systems to prevent corrosion.
AASHTO M240: Performance criteria for protective coatings (e.g., epoxy, polyurethane) in harsh environments.
AASHTO is mandatory for:
Projects funded by multilateral agencies (World Bank, African Development Bank), which support 80% of Liberia’s infrastructure rebuild (Liberian Ministry of Public Works, 2023). For example, the $200 million Liberia Road Rehabilitation Project (LRRP) requires all bridges to comply with AASHTO LRFD.
Bridges carrying heavy freight (e.g., mining trucks weighing 80+ tons). AASHTO’s load calculations (e.g., HL-93 design truck) ensure structures can withstand repeated heavy loads without failure.
Coastal or humid regions. AASHTO’s corrosion protection guidelines are tailored to high-moisture environments—critical for Liberia’s Atlantic coastline and rainy seasons.
For our company, AASHTO compliance is non-negotiable: we align our fabrication (e.g., welding to AASHTO AWS D1.5) and surface treatment processes with these standards to qualify for Liberia’s funded projects.
Liberia’s infrastructure gap creates urgent demand for steel bridges:
Post-conflict reconstruction: Over 70% of pre-war bridges were destroyed or rendered unsafe (e.g., the Mesurado River bridge in Monrovia). Temporary crossings (e.g., ferries, bailey bridges) are slow and cannot support freight.
Economic growth: Mining (Liberia’s top export) requires bridges that carry 100-ton ore trucks. Concrete bridges, which take 2–3 years to build, cannot meet the sector’s timeline needs.
Climate resilience: Liberia faces annual floods and tropical storms. Steel’s ductility (ability to bend without breaking) makes it more resilient than concrete, which cracks under flood pressure.
A 2023 survey by the Liberian Ministry of Public Works found that 85% of local governments prioritize steel bridges for their rapid construction and low maintenance costs.
Steel box girders are the top choice for Liberia’s high-priority projects due to:
Span requirements: Liberia’s major rivers (St. John, St.Paul，Mesurado) require spans of 150–250 meters—beyond the capacity of beam or truss bridges.
Urbanization: Monrovia’s population is growing at 4% annually, increasing demand for urban overpasses (e.g., the planned Paynesville-Monrovia Overpass) to reduce traffic.
Cost-effectiveness: While steel has a higher upfront cost than concrete, its 75-year service life (vs. 30–40 years for concrete) lowers lifecycle costs. The Monrovia River Crossing Bridge, for example, is projected to save $1.2 million in maintenance over 20 years compared to a concrete alternative.
Our company supplied prefabricated steel box girders for this $18 million project, funded by the African Development Bank. Key details:
Background: The previous concrete bridge (destroyed in 2003) caused daily traffic jams of 2–3 hours. The project aimed to restore connectivity between central Monrovia and the port.
AASHTO compliance: Designed to AASHTO LRFD (HL-93 load, wind speed 150 km/h), with girders fabricated from A572 Grade 50 steel.
Surface treatment: We applied a three-layer coating system (epoxy zinc-rich primer, epoxy micaceous iron oxide intermediate, aliphatic polyurethane topcoat) to combat coastal corrosion.
Impact: Post-completion, travel time between Monrovia and the port dropped by 40%, and daily truck throughput increased from 150 to 400 vehicles. Local businesses reported a 25% increase in export efficiency within 6 months.
This project demonstrates why steel box girders are now Liberia’s preferred bridge type: they deliver speed, durability, and economic value.
Steel box girder bridges drive Liberia’s growth in three key ways:
Economic integration: Connecting ports to inland mining and agricultural zones reduces transport costs. The planned Buchanan River Crossing Bridge (220m span, our company’s proposal pending) will cut iron ore transport costs by 15%, making Liberian ore more competitive globally.
Regional trade: As part of the Economic Community of West African States (ECOWAS), Liberia needs cross-border bridges (e.g., the proposed Mano River Union Bridge to Côte d’Ivoire). Steel box girders’ large spans and rapid construction align with ECOWAS’s 2030 regional connectivity goals.
Job creation: While girders are prefabricated in our global factories, on-site assembly creates local jobs. The Monrovia project employed 120 local workers (trained by our technical team) in welding, installation, and quality control—supporting Liberia’s goal of reducing youth unemployment (38%, World Bank 2023).
The future for steel box girder bridges in Liberia is robust:
Government planning: The 2023–2030 National Infrastructure Plan identifies 12 priority bridge projects, 8 of which are designated for steel box girders (e.g., Gbarnga-Monrovia Highway Bridge, Harper Coastal Viaduct).
International funding: The World Bank’s 300 million Liberia Infrastructure Resilience Project (LIRP) ear marks 80 million for AASHTO-compliant steel bridges, with a focus on climate-resilient design.
Our company’s role: With our track record in the Monrovia project, we are well-positioned to support these initiatives. We offer end-to-end solutions: AASHTO-aligned fabrication, custom surface treatment for Liberia’s climate, and on-site technical support. We have already submitted bids for the Buchanan and Harper projects, highlighting our ability to deliver girders within 4 months of order—critical for meeting Liberia’s tight timelines.
Liberia’s environment is highly corrosive to steel:
Tropical humidity: 80–90% relative humidity year-round accelerates oxidation (rust).
Coastal salt: Airborne salt from the Atlantic affects bridges within 50km of the coast (e.g., Monrovia, Buchanan).
Rainfall: Annual downpours wash away unprotected steel, while standing water in girder cavities causes localized corrosion.
Without proper surface treatment, steel bridges in Liberia can degrade in 5–10 years. AASHTO standards address this, but successful implementation requires customization to local conditions.
AASHTO M280 and M240 set strict criteria for corrosion protection:
Surface preparation: Abrasive blast cleaning to Sa2.5 (near-white metal) or Sa3 (white metal) to remove all rust, oil, and contaminants. For coastal projects like Monrovia, we use Sa3 (per AASHTO’s recommendation) to eliminate residual corrosion.
Coating systems: AASHTO mandates multi-layer systems for durability. For Liberia, we recommend:
Primer: Zinc-rich epoxy (AASHTO M274), dry film thickness (DFT) 80μm—provides cathodic protection (zinc sacrifices itself to protect steel).
Intermediate coat: Epoxy micaceous iron oxide (AASHTO M281), DFT 120μm—acts as a barrier to moisture and chemicals.
Topcoat: Aliphatic polyurethane (AASHTO M300), DFT 80μm—resists UV degradation (critical for Liberia’s intense sunlight) and provides a durable, easy-to-clean finish.
Quality control: AASHTO requires:
DFT testing (magnetic gauge) to ensure compliance.
Adhesion testing (pull-off strength ≥5 MPa).
Salt spray testing (ASTM B117, 1,000 hours) to validate corrosion resistance.
As exporters, we go beyond AASHTO’s minimums to address Liberia’s unique challenges:
Enhanced DFT: For coastal bridges, we increase total DFT to 280μm (vs. AASHTO’s 240μm) to extend protection. In the Monrovia project, this extra thickness has prevented corrosion for 2+ years.
Pre-fabrication coating: All girders are fully coated in our factory (controlled temperature/humidity) before shipment. On-site touch-up is limited to welds, using the same coating system and supervised by our QC team—avoiding rain-related coating failures common in Liberia.
Cavity protection: Steel box girders have internal cavities prone to moisture buildup. We install drainage holes (per AASHTO) and apply a thick epoxy coating to cavity interiors, preventing hidden corrosion.
Sacrificial anodes: For submerged components (e.g., pier-girder connections), we add zinc sacrificial anodes (AASHTO M294) to provide additional cathodic protection—extending service life by 15–20 years.
Maintenance support: We provide Liberia’s Ministry of Public Works with a 5-year maintenance plan, including annual coating inspections (using our portable DFT gauge) and touch-up kits. This proactive approach ensures long-term performance.
In 2023, a third-party audit (commissioned by the African Development Bank) evaluated the Monrovia Bridge’s surface treatment:
No blistering, peeling, or rust was observed.
DFT remained at 265μm (only 5% loss from the original 280μm).
Salt spray test results (simulating 5 years of coastal exposure) showed no corrosion.
These results confirm that our AASHTO-aligned, customized surface treatment meets Liberia’s needs and delivers on the bridge’s 75-year service life commitment.
Steel box girder bridges, built to AASHTO standards and paired with optimized surface treatment, are a catalyst for Liberia’s infrastructure revival. Their rapid construction, large-span capability, and durability address the country’s post-conflict needs, while their role in connecting economic hubs drives national and regional growth. As an experienced exporter, our company is committed to supporting Liberia’s development: we deliver AASHTO-compliant components, tailor surface treatment to local climatic challenges, and provide end-to-end technical support—proven by the successful Monrovia River Crossing Bridge.
With Liberia’s 2030 infrastructure plan and ongoing international funding, the demand for steel box girder bridges will only grow. We stand ready to partner with the Liberian government, multilateral agencies, and local stakeholders to build bridges that are safe, durable, and inclusive—bridges that not only span rivers but also connect Liberia to a more prosperous future.
African Development Bank. (2023). Liberia Infrastructure Assessment Report. Abidjan, Côte d’Ivoire.
AASHTO. (2020). AASHTO LRFD Bridge Design Specifications (8th ed.). Washington, D.C.: American Association of State Highway and Transportation Officials.
Liberian Ministry of Public Works. (2023). National Infrastructure Plan 2023–2030. Monrovia, Liberia.
World Bank. (2023). Liberia Economic Update: Building Resilience for Inclusive Growth. Washington, D.C.: World Bank Group.
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