On a recent cold, gray morning, state bridge inspector Van Swift jumped into his office: a 4-by-3-foot white bucket at the end of a 60-foot hydraulic arm anchored to a flatbed "snooper" truck.
Working a cluster of joysticks, he swung the bucket away from the truck and over the side of the 800-foot Interstate 70 bridge spanning the Patapsco River between Baltimore and Howard counties. As the bucket descended, the whoosh of highway traffic gave way to the rumble of tires overhead.
Swift maneuvered the bucket toward a web of girders, beams and turnbuckles about 120 feet above the rushing water. He slowed to check critical connections, nodding at repairs that have withstood the test of time and tension, and pausing intermittently to take notes about new areas of concern.
In waders and in bucket trucks, in teams of two and three, inspectors fan out across Maryland every day, poking at the aging underbelly of the state's highway infrastructure. Four percent of the 2,578 bridges maintained by the State Highway Administration are classified as structurally deficient: safe for travel but in need of repair or replacement.
Discolored concrete, exposed metal reinforcing bars, cracks, chips and missing pieces all signal that weather and time are taking their toll.
The inspectors measure deterioration with rulers and gauges that determine tilt. They prod weaknesses with pick hammers. Suspect areas are photographed.
"You have to take very detailed notes because when you write that report, it's like painting a picture for the engineers back at headquarters," said the SHA's Frank Mills, who supervises 17 inspectors statewide.
The SHA crews check each bridge maintained by the agency at least every two years. The Maryland Transportation Authority, which has responsibility for toll roads and bridges, monitors an added 317 major spans, of which just one is structurally deficient.
Local jurisdictions are responsible for inspecting their own bridges. Twenty-one need to be replaced in Baltimore, according to Mayor Stephanie Rawlings-Blake.
Every bridge is different, with structural aches and pains that differ with age, traffic load and design, and are exacerbated by the elements.
Under the I-70 bridge over the Patapsco, Swift noticed an arrow along one beam near the road decking and a warning — "watch" — written in brown paint and dated 9/26/11.
"It's like a Post-It note that won't go away," he said. "That weld may go bad. It may never go bad. But we know to go back and keep an eye on it."
Politicians have debated the nation's aging infrastructure for years. About 12 percent of the nation's 600,000 bridges are structurally deficient, according to a federal study in 2009.
President Barack Obama announced plans this week to spend $50 billion to rehabilitate roads, bridges, airports and transit lines. But with Washington deeply divided over deficit reduction, any spending is in doubt.
"Most bridges are designed with a 40-year life span, so a lot of bridges are near the end," said Tony Dorsey, spokesman for the American Association of State Highway and Transportation Officials. "We have a lot of baby-boomer bridges. A lot of us need hip replacements and knee replacements. These bridges are in the same shape we're in."
In Maryland, state officials say $700 million more a year is needed for transportation infrastructure projects, including bridges.
Maryland's highway administration spends about $155 million a year on bridge replacement and rehabilitation. The agency repaired or replaced 18 structurally deficient bridges in fiscal year 2012, according to its report to the General Assembly.
The list is fluid, but the number of bridges rated structurally deficient in Maryland decreased for the sixth straight year. The total went from 143 in 2006 to 97 in 2012.
Of the 97 bridges, 32 are under construction or have been put out to bid and 65 are in the design phase.
The I-70 bridge shows wear at 48 years old and handles an average of 95,245 vehicles daily. While it maintains a Federal Highway Administration sufficiency rating of 68.8 percent, a passing grade, the state inspects it every year. The reason, in engineering terms, is that the span has a "fracture-critical" design typical of bridges built in the 1960s. While the ends of the bridge are supported by multiple girders, the center has but two main girders.
"That means if one fails, we're in big trouble," said Mills. "The whole thing would come down."
The lack of structural redundancy doomed the Interstate 35 bridge in Minneapolis, which collapsed in 2007, killing 13 people and injuring 145. In addition to the I-70 bridge, Maryland has 289 bridges that lack structural redundancy.
"There's a lot of importance in what we do. That's what keeps you focused," said Kevin Callahan, a Towson University graduate who has been inspecting bridges for nearly three years.
Another thing that keeps the inspectors on their toes is their surroundings.
While some bridges are little more than culverts carrying rural byways over trickles of water, others, such as the I-70 span and the Gov. Thomas Johnson Bridge, which carries Route 4 over the Patuxent River in Southern Maryland, soar above the landscape. The snooper truck's bucket shimmies and bounces when it changes direction or is buffeted by the wind.
"The Thomas Johnson is about 140 feet up," Callahan said. "You get to the middle of the span and you find out if you're afraid of heights or not."Copyright © 2015, CT Now