The crack on a steel girder on the underside of the westbound Interstate 70 bridge over the Patapsco River was so small that it wouldn't catch the eye of most.
But within a half-hour of a bridge cleaning-and-painting contractor spotting it, a structural engineer with the State Highway Administration was on scene, and the bridge was closed to traffic.
About 100,000 vehicles travel over the bridge daily, and all were detoured for two days earlier this month as repairs were made. SHA Administrator Melinda Peters said her agency is "very conservative" when it comes to assessing bridge safety, and was "erring on the side of caution."
The decision to immediately put contractors to work shoring up the bridge was also in line with the agency's evolving modus operandi, officials said, of using newly available resources to bring an ever-increasing number of bridges into good condition before small issues become major problems.
"We've really been able to kick that up," said Earle "Jock" Freedman, longtime director of the SHA's Office of Structures, including bridges.
Local concerns about deteriorating infrastructure have increased recently following the collapse of a large retaining wall in Charles Village and the recent closure of Interstate 495 in Wilmington after the discovery of serious damage to several bridge supports there. The brief closure of I-70, as a result, led to more questions than normal from the already concerned public, said Valerie Burnette Edgar, a SHA spokeswoman.
But in Maryland in recent years, cause for concern should actually be going down, SHA officials said, because significant progress has been made improving the condition of state-maintained bridges — largely thanks to dramatic increases in annual bridge repair funding, including from the state.
"We've really been getting good funding," Freedman said. "We've gotta be looking at these bridges and finding potential [problems] rather than reacting to things that we didn't expect."
"If you don't take care of your house, you're going to have problems," said Rod Thornton, the SHA's division chief of bridge design and rehabilitation, on the agency's "preventative measures" approach.
According to SHA data, funding for "Bridge System Preservation" has jumped from $62.2 million in fiscal 2002 to $176.1 million in fiscal 2014. In the same period, the number of "structurally deficient" bridges in the state fell from 148 to 81 — or about 3 percent of the 2,700 bridges the state is responsible for, Freedman said.
That percentage is "probably as low as any state in the country," he said. "I know we're the lowest in the region."
Burnette Edgar said the state bridge program is funded through a mix of state and federal dollars, but the increased state gas tax has been a major factor in its funding increase by boosting state support and attracting more matching federal dollars.
With its increased funding, Freedman said, his office has gone from deploying 12 teams of bridge-repair contractors to 30 teams doing three times as much preventative maintenance.
Ragina Cooper-Averella, a spokeswoman for AAA Mid-Atlantic, said the progress on bridge conditions in the state is a positive, despite coming on the backs of taxpayers.
"While nobody wants to see an increase in the gas tax, it's encouraging that the state is able to tackle some of these projects," Cooper-Averella said. "In the interest of safety, we want the state to be able to do what it needs to do."
Many bridges in Maryland are older, and many continue to deteriorate, falling from "fair" ratings in state inspections, which are required every two years, to "structurally deficient," officials said. But repairs are outpacing the deterioration.
Since 2006, for example, 85 aging bridges have been added to the structurally deficient list, but 141 have been repaired or replaced.
The state's bridges have also benefited from more than $160 million invested per year for the last three fiscal years in roadway improvement projects involving bridges but not funded through the bridge budget.
Structurally deficient bridges are considered safe for travel — they would be closed otherwise — but are in need of upgrades, Freedman said. Along with their drop at the state level, those maintained by the state's counties and Baltimore City have also fallen, data show, from 274 in fiscal 2002 to 225 in 2014. That's just under 10 percent of the 2,300 locally maintained bridges.
The extent to which the SHA can maintain its pace may depend in part on the federal government's shoring up its own transportation fund, which has been depleted for years as legislators squabble over how to foot the bill.
Still, Freedman said, the SHA expects bridge funding to remain well above where it was a decade ago. It also expects the added benefit of newer bridges having longer life spans and a new technology out of the University of Maryland.
The SHA has been helping Mehdi Kalantari, a university research scientist, test a new sensor he developed at a university incubator that can alert officials to small movements within bridge substructures.
According to Kalantari, the sensors — now being marketed commercially by his company, Resensys — would have alerted officials in Delaware to their bridge piers shifting. They also would have alerted SHA officials to a jammed bearing not allowing the I-70 bridge to expand with temperature fluctuations, which they suspect was the cause of the crack.
"Anything that causes damage to the structure is going to be detected right away," Kalantari said.
Freedman said the SHA already has several sensors in place, and plans to install them on more bridges soon, including both I-70 bridge spans.