WASHINGTON – Climbing over large spans, whacking them with hammers, listening for hollow sounds, and examining every foot for defects, Maryland’s bridge inspectors try to ensure what motorists may take for granted: safe bridges.
Joseph R. Miller, chief of the Maryland State Highway Administration bridge inspection division, oversees six three-man inspection teams, who check the condition of 2,400 bridges.
Maryland’s other 2,400 bridges are maintained by the counties.
“We’re looking for any defects,” said Bruce Jenkins, 33, a bridge inspector since 1985 and now an inspection team leader for bridges in Baltimore County. “We sound the concrete, check for hollow sounds, any defects, look for cracks, any small openings.”
Hanging up to 135 feet above water, land or concrete, and facing the constant threat of passing traffic, inspectors put their own safety on the line as they protect that of travelers.
Traffic imposes an ever-present risk.
“We’ve had people killed by drunk drivers,” said Valerie Edgar, a SHA spokeswoman. “It’s very dangerous, and that’s why we’re always promoting, `Slow down in work zones.’ ”
As required by federal law, Maryland’s bridges are inspected at least once every two years, an effort costing around $2 million a year, Miller said. Each team is responsible for 200 bridges a year.
Miller said the bridge division operates on an annual budget of $60 million, with $20 million in state funds going for maintenance. The remaining $40 million – 80 percent of it federal funds – is directed to bridge repair and replacement.
To qualify as an inspector for the state or its counties, an individual must either be a professional engineer, licensed in Maryland, or have completed a two-week federal training course.
All 18 of Miller’s inspectors have qualified by completing the two-week course, he said.
On average, they have seven years of experience. “They’re a special breed,” said Earle S. Freedman, a deputy chief engineer for the SHA.
Some jurisdictions, such as Frederick County, inspect their bridges with in-house personnel. Others, such as St. Mary’s County, hire consultants. About three-quarters of the county bridges are inspected by consultants the state has hired, said Lloyd Lipin, county bridge inspector coordinator.
Inspectors are taught to look for, among other problems, concrete deterioration, the thinning of steel because of rust and cracks, paint decay, rust, leaking joints and frozen bearings.
For bridges whose bases rest in or near water, “scour” can be a major problem inspectors attempt to detect early. Scour occurs when bedding material supporting the base of the bridge is eroded by water.
“The Grand Canyon is a great example of scour,” Miller said.
Inspections of bridges crossing water require boats, waders, and in some cases, professional divers, who may have to descend 60 feet or more beneath water.
Steel bridges present the added problem of weakened steel, or “fatigue.” Since bridges must maintain a certain degree of flexibility in order not to crack, years of movement can take its toll, Miller said.
He compared fatigue with the gradual weakening of a paper clip that’s bent back and forth.
Inspectors refer any problems to the state’s structural engineers.
Jenkins said 10- or 15-year-old bridges rarely have anything wrong with them. More often, he said, problems are spotted among older bridges.
“The average life span of a bridge is 40 to 60 years,” Miller said. The deck, or road, of a bridge will last 20 to 30 years, “so we aim for one replacement deck before the bridge has to be replaced.”
Much of the inspectors’ work is performed from twin baskets attached to the end of a long hydraulic arm extending from the back of a quarter-million-dollar truck called a “snooper.”
The arm extends up to 45 feet, enabling inspectors to examine the top, outside and underside of any bridge. “The hardest thing,” said Jenkins, “is getting into a position so you can do your hands-on inspection.”
Working in and around heavy equipment presents its own unique dangers. In 1982, an inspector examining a bridge in Crumpton, in Kent County, came in contact with power lines and was hospitalized after being jolted with 25,000 volts.
The inspector, working from the bucket of a snooper truck, “reached out with his hammer and hit a metal beam, grounding himself,” Miller said. “All the power went through him.
“He’s in bridge design now,” Miller said.
On another occasion, a passing truck hit the bucket truck, knocking the inspector out of the bucket. “He landed on the hood of his own truck,” Miller said.
In 1978, inspectors landed in jail after pulling up a rope attached to the railing of a bridge in Essex, in Baltimore County.
Finding a suitcase attached to the end of the rope, the inspectors returned to their van and discovered it was stuffed with cash. “When they opened it,” Freedman said, “here came the FBI, here came the state police, guns pointed at their throats.”
The inspectors had inadvertently picked up ransom money involved in the stakeout of a bank robber.
“They caught the guy at 1 p.m.,” Miller said. “They didn’t let our guys out until 5 p.m.”
When hiring inspectors, Miller said, “We tell them they can’t be afraid of heights, and they’ve got to be quick on their feet.”