Why the Cheapest Bridge to Build Is Rarely the Cheapest to Own

The Bid-Day Problem

Bridge projects are awarded on low bid. The contractor with the cheapest construction number wins. Owners know this. Engineers know this. Everyone optimizes accordingly.

But construction cost is only the first line item. A typical highway bridge has a design life of 75 years. Over that span, the owner will pay for biennial inspections, deck overlays every 15 to 25 years, bearing replacements, joint repairs, rehab projects, and eventually a full replacement. FHWA estimates put total lifecycle cost at 2 to 3 times the original construction cost for many structures. The bridge you build on the cheap often becomes the bridge you pay for twice.

What Lifecycle Cost Actually Covers

Lifecycle cost analysis (LCCA) accounts for every dollar spent on a structure from construction through demolition. The major categories:

• Initial construction including materials, labor, equipment, and mobilization
• Routine maintenance such as cleaning, sealing, and minor concrete repair
• Preventive maintenance including deck overlays, painting, and joint replacement
• Major rehabilitation like deck replacement, bearing swap-out, or substructure repair
• User costs from lane closures and detours during maintenance events
• End-of-life costs for demolition and replacement

For a prestressed concrete bridge, a single deck overlay runs $30 to $50 per square foot. Over 75 years, a structure might need two or three. Expansion joint replacements run $500 to $1,500 per linear foot depending on joint type. These numbers add up fast.

Where Low-Bid Design Choices Cost More Later

Certain design decisions reduce construction cost at the expense of durability. A few common ones:

Thinner deck sections. A thinner deck uses less concrete and rebar up front. It also has less cover over the reinforcing steel. In northern states with deicing salt exposure, reduced cover accelerates chloride-induced corrosion, leading to earlier overlay or deck replacement cycles.

Fewer expansion joints. Eliminating a joint saves money during construction. But concentrating thermal movement at fewer locations increases stress on the remaining joints and bearings, shortening their service life.

Wider beam spacing. Fewer beams means fewer lines to set, which reduces erection cost. But wider spacing increases the load demand on each beam and the deck slab, which can limit future load rating capacity if truck weights increase or the owner needs to re-rate the structure.

Minimal corrosion protection. Epoxy-coated rebar, stainless steel reinforcement, and high-performance concrete mixes all add to initial cost. Skipping them saves money on day one and creates a maintenance liability that shows up 15 to 20 years later.

None of these are bad engineering decisions in isolation. They become problems when the tradeoff between construction cost and long-term cost is never quantified.

The Real Issue: Nobody Runs the Numbers Across the Full Design Space

An engineer designing a bridge can run a lifecycle cost estimate for a single configuration. Maybe two or three if the schedule allows. But there are thousands of valid structural configurations for any given crossing, each with a different cost profile over time. A wider beam at closer spacing might cost 4% more to build but eliminate an overlay cycle, saving the owner $800,000 over 50 years.

That tradeoff exists in the design space. It just never gets found, because no one has time to evaluate it manually.

Scoring Every Variant on Lifetime Cost

This is what changes when you can simulate thousands of structural configurations and score each one not just on material cost, but on total cost of ownership. Different designs win.

The cheapest-to-build option might rank fifteenth when you factor in maintenance intervals, expected rehab costs, and user delay costs from lane closures. The variant that actually minimizes total owner expenditure is often one that no engineer would have selected manually, because the savings only become visible when you model the full 75-year cost trajectory across hundreds of alternatives.

Arched scores every generated variant on lifetime cost alongside construction cost, carbon, and constructability. The engineer sees the full picture and picks the design that matches the owner's priorities, whether that is lowest upfront cost, lowest lifecycle cost, or a balance of both.

Getting Started

If you want to see how lifecycle cost varies across the design space for an upcoming bridge project, send us a plan set. We will return an optimization report that includes lifetime cost rankings alongside construction cost and code compliance for every validated alternative.