Bridge work pulls out all stops

Traffic flow a priority in four-year overhaul of Chesapeake span

March 02, 2002|By Chris Guy | Chris Guy,SUN STAFF

Almost 30 years ago it was all fanfare and celebration as state dignitaries paraded across the 4.3-mile-long new bridge in a caravan of antique cars to mark the completion of the three-lane westbound Chesapeake Bay Bridge span.

Curious motorists and beach-goers stacked up traffic for miles that first weekend in late June 1973, anxious to glimpse the graceful curve of concrete and steel that, with its older two-lane sister span, would speed 7 million vehicles to and from Ocean City and other Eastern Shore destinations that year.

Now, as work crews are beginning a $45 million overhaul of the worn-out 38-foot-wide roadway, the mood among transportation officials, truckers, tourists and an ever-growing number of Eastern Shore commuters is something like grim resignation in the face of a project that will take four years.

The problem is simple: The concrete and steel that make up the bridge roadway simply don't last much longer than three decades.

The trick, say Maryland Transportation Authority officials, is getting the job done in the middle of 24 million or so vehicles that will cross the twin spans this year - almost four times as many as when the westbound span opened. That, says project manager Mitchell Rubin, means throwing out conventional construction methods.

If there is a way to make life difficult for work crews, he says, this job has it.

"This one is unique, it's especially difficult because it's 180 degrees different from our normal schedule," says Rubin, directing the work for the employee-owned construction giant, Cianbro Corp. "Normally, most of our work is going to get done in the spring, summer and fall. On this one, because of the beach traffic, it's exactly the opposite; we'll be very limited during the summer."

The two-phase project is an extensive undertaking requiring more than 33 million pounds of concrete, all reinforced with 1.5 million pounds of steel rods. Equal amounts of concrete and steel have to be milled, sawed and jack-hammered, then hauled away.

And that's not counting another 5.5 million pounds of new steel as the bridge's railings are repaired or replaced.

As a bonus, engineers are designing an alternative to the tricky steel wind grates at the top of the span that make many motorists skittish, especially in wet weather.

The next couple months should be fairly easy, says Rubin, but the restrictions stiffen as summer approaches.

The center lane can remain closed until April 15, and workers are allowed to intermittently close other lanes during the day until May 15 - changes that have slowed traffic during peak periods.

But once the tourist season kicks in on May 15, crews will be working only at night, 11 p.m. to 6 a.m., through Sept. 15. The contract prohibits weekend closures from Memorial Day to Labor Day, and all lanes must be kept open on holidays the rest of the year.

Already, night crews have been working under high-intensity lights 186 feet above the bay, closing two lanes at a time between the evening rush hour and 6 a.m.

If there was any doubt that the state means business about trying to limit inconveniences for motorists, the company will be hit with fines of $1,000 a minute if workers are late clearing barriers and opening lanes for the morning rush hour, a necessity because almost one-third of the vehicles using the bridges are driven by commuters.

"We've had a lot of brain power on this for a long time," says transportation authority spokeswoman Lori Vidil. "In terms of the scope of what the authority does, it's a big project," but not the agency's biggest by far. However, she added: "In terms of visibility, it's very big. This is the way to the beach."

The way the engineers look at it, the bridge is 123 separate spans, ranging from 60 feet to 1,600 feet long, all requiring repair or replacement of concrete and steel subject to corrosion from salt and weather and pounding from traffic that ranges from 3,500 to 4,000 vehicles an hour in peak periods.

"It's really a surgical kind of approach," says Umesh P. Murthy, deputy director of design for the MdTA's engineering division. "It's a matter of determining when you reach that end of useful life, where maintenance just isn't cost effective any more."

So far, workers have been using a $300,000 milling machine to grind away the first two inches of concrete decking in sections that can be rehabilitated, which will be replaced with two types of concrete.

In portions that need total deck replacement, high-powered saws with industrial diamond blades worth $2,000 apiece will slice through the seven-inch roadway, including deteriorated steel reinforcing rods that must be scrapped.

But first, workers must install 175,000 square feet of shielding deck pans 5 1/2 feet below the roadway. The deck pans will catch any debris and will later provide a surface for heaters that will help cure concrete poured under less than optimum conditions.

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