Lifecycle Cost Analysis: FRP vs. Cast Iron Over 30 Years

Manhole covers are a critical component of urban infrastructure, and their lifecycle costs—encompassing purchase, installation, maintenance, and replacement—significantly impact municipal budgets. Comparing Fiber Reinforced Plastic FRP manhole cover and cast iron manhole covers over a 30-year period reveals stark differences, with FRP offering substantial savings. This lifecycle cost analysis highlights why FRP is the superior choice.

Initial Costs: Cast iron manhole covers typically cost $200–$500 each, depending on size and load rating, while FRP covers range from $300–$600. At first glance, cast iron appears cheaper. However, installation costs shift the equation. Cast iron covers, weighing 100–300 pounds, require heavy equipment and larger crews, costing $500–$1,500 per installation. FRP covers, at 20–50 pounds, can be installed by one or two workers without machinery, reducing installation costs to $200–$500. For 1,000 covers, initial savings with FRP could reach $300,000.

Maintenance Costs: Cast iron is prone to rust, especially in coastal or wastewater environments, requiring regular painting, galvanization, or cleaning at $100–$500 per cover every 3–5 years. 

The cost of maintaining 1,000 coverings over 30 years might range from $1.5 to $3 million. FRP, being corrosion-resistant, requires no coatings or repairs, with maintenance costs near zero. This alone saves millions over decades.

Replacement Costs: Cast iron covers last 10–15 years in corrosive environments, necessitating 2–3 replacements over 30 years. Each replacement cycle, including materials and labor, costs $700–$2,000 per cover, totaling $2–$4 million for 1,000 covers. FRP covers, with a lifespan of 20–50 years, typically require no replacements in 30 years, saving up to $4 million.

Theft and Safety: Cast iron covers, valued for scrap, are frequently stolen, with replacement costs of $500–$2,000 per incident. Assuming 10% of covers are stolen over 30 years, losses could reach $500,000 for 1,000 covers. FRP covers, lacking scrap value, deter theft, eliminating this expense. Additionally, corroded cast iron covers pose safety risks, potentially leading to lawsuits costing millions, while FRP’s durability minimizes such risks.

Total Lifecycle Costs: For 1,000 covers over 30 years, cast iron incurs $4–$8 million in costs (initial, maintenance, replacements, theft). FRP costs $500,000–$1 million upfront, with negligible maintenance and no replacements, totaling $1–$1.5 million. This represents savings of 70–80%. Cities like Singapore, adopting FRP, report similar reductions, reinvesting savings into infrastructure. Despite higher initial costs, FRP’s lifecycle savings make it the financially prudent choice.