A Foundational Intro to Bridge Engineering
Posted on November 7, 2025
It’s a common trope in fiction: A rickety wooden-plank bridge sways with the wind over a yawning chasm — its feeble, tenuous ropes ready to snap upon a hiker’s sudden step.
Thankfully, in the real world, bridge and structural engineers use their skill and expertise to design sturdy bridges that help people cross to the other side safely and without trepidation.
Levon Arakelov, PE, a senior bridge engineer at Anderson, Eckstein & Westrick, Inc., has more than 45 years of design and engineering experience, which includes past work for the City of Detroit and the Michigan Department of Transportation.
Arakelov explained that bridge engineering can be divided into three main categories: design, construction, and maintenance.
Design-focused bridge engineers create designs that have the capacity to carry traffic based on state or federal requirements. These engineers need to abide by those government requirements while complying with bridge geometrics and designing a bridge that can last.
According to Arakelov, design engineers also consider the need for bridge resilience against heavy traffic or extreme weather, looking at factors such as self-weight, live loads, temperature, winds, and ice loads. He also explained that a bridge designer must make sure that precipitation will drain off the bridge and not remain to pose a hydroplaning risk for traffic.
“It has to be designed so that water will not stay on the bridge,” he said. “It has to be properly sloped.”
Without proper maintenance or construction practices, bridges’ load carrying capacity can be reduced, and members could start to fail, resulting in costly repairs, traffic shutdowns, and even putting the public at risk.
Bridge engineers inspect bridges and make reports that ensure that bridges’ conditions can safely handle their expected traffic capacity. These engineers also make recommendations to bridge owners for plans of action on the best maintenance and repair options to keep bridges functioning as they should.
As a bridge’s condition deteriorates over time, it may have a reduced load posted, or it may need to partially or completely close. Bridges should generally be inspected at least once every 24 months, with some bridges requiring more frequent attention, Arakelov said.
“By federal requirements, each bridge has to be inspected, first initially when it’s built and then every 24 months,” he said. “During that period of time, the bridge inspector will be looking for any deficiency, any deterioration, any environmental impacts.”
When something goes awry with a bridge, the culprit may be poor maintenance or neglect, which can harm a bridge’s condition over time and bring it closer to failure.
“Basically, it’s not going to happen suddenly,” he said. “Anywhere in the country a bridge fails, it means the bridge was not maintained or designed or constructed correctly.”
In short, bridges require great care, attention to detail, and a foreknowledge of what can go wrong.