At 12:21 p.m. yesterday, there came a scraping sound as a 130-foot-high crane standing on the floor of the Herring Run valley in Northeast Baltimore began tugging upward on a more than 7-ton piece of concrete and steel rebar that had supported the Argonne Drive bridge since Dwight D. Eisenhower was president.
Eight minutes later, after being slowly plucked from the bridge pier and eased to the ground, the massive chunk of 1950s infrastructure was resting on the valley floor.
"It's always delicate," said Rick Slamon, superintendent for contractor American Infrastructure.
The removal of the pier cap was just one step on one project in a stepped-up effort by the city Department of Transportation to repair or rebuild dozens of its aging bridges in Baltimore and surrounding counties. In addition to three projects under way, another dozen are expected to begin before next summer.
In a way, all the construction sounds at the Argonne Drive site — and the two other projects — are echoes of the 2007 collapse of Minnesota's Interstate 35W bridge into the Mississippi River.
The sudden crumbling of that vital span, which killed 13 people and cut off an important commuter route serving Minneapolis, forced transportation officials around the country to take stock of their own bridges. Here in Baltimore, they didn't like what they found.
But after years of planning and engineering, the city is moving into high gear in its bridge replacement efforts. Between now and 2017, Baltimore expects to undertake an average of 6-7 bridge projects a year at a cost of more than $300 million. That contrasts with a pace of one or two a year in the 2005-2009 budget years, said deputy city transportation director Jamie Kendrick.
"This is a pretty significant turnaround for where we are," Kendrick said. "This is a total change in our approach to bridge management."
While the projects are expected to make the city safer for travel in the long term, the effort is bound to involve delays and detours over the next several years as lanes — and, in some case, entire bridges — are closed for extensive periods.
The projects under way or about to be launched over the next year affect many different parts of the city and its county neighbors. Of the 312 bridges maintained by the city, 23 are in Baltimore County and one each in Carroll and Harford, where the city owns property as part of its water system.
The current projects include one of those county bridges — on Nicodemus Road over Liberty Reservoir linking Baltimore and Carroll counties. That 57-year-old bridge is being replaced down to its footings in an $11 million project that involves replacing piers that stand in 90 feet of water.
In addition to the $5.5 million Argonne replacement, the other project in the city is the repair and resurfacing of the vintage 1976 Pennington Avenue bridge over Curtis Creek in industrial South Baltimore. Originally budgeted for $15 million, the cost of that project grew another $10 million when its problems were found to be more serious than anticipated.
The current fiscal year, which started July 1, is expected to bring another $44.3 million in work on a dozen projects — including replacement of the badly deteriorated Fort Avenue bridge over the CSX tracks in Locust Point and the Frederick Avenue bridge over the Gwynns Falls in West Baltimore. Most of the bridges slated for repair next year were built in the 1930s and 1950s, but the CSX bridges over Sinclair Lane and Fort Avenue date back to 1900 and 1920 respectively.
According to Kendrick, the Minnesota tragedy made an indelible impact on city officials' thinking about its aging infrastructure.
"Obviously the I-35 bridge collapse was a huge wake-up call nationally," he said.
The bridges scheduled for reconstruction projects in Maryland include many with federal "bridge sufficiency" ratings that are even lower than the 50 on a 100-point scale recorded by the I-35W bridge before it collapsed. However, none of the city-owned bridges involves an interstate carrying heavy traffic over a wide river, as the Minnesota span did.
Of Baltimore's hundreds of bridges, there are relatively few that would register as such to the typical motorist passing over them. Many cross small streams or culverts. Others are parts of elevated roads such as the Jones Falls Expressway, which is largely made up of a series of bridges. Some support ramps. A few, such as Central Avenue in East Baltimore, are perched over long covered-over streams and are hardly recognizable as bridges.
"You're really on bridges all the time and you don't know it," said veteran City Councilwoman Mary Pat Clarke. "I was riding on Argonne all the time and I didn't know it was a bridge."
But Clarke said constituents learn quickly how much they depend on bridges when one closes entirely, as the Argonne bridge did after its structural problems were determined to be worse than previously thought.