Quick fix for I-93 bridges begins
14 spans set to be rebuilt over the summer; weekend work will affect traffic
MEDFORD — The state late last night closed half the lanes along a 5-mile stretch of Interstate 93 north of Boston, the start of a major construction project that promises to slow traffic most weekends this summer on a road carrying nearly 200,000 vehicles every day. The restrictions are being imposed so that the state can replace 14 decaying highway bridges, all more than 50 years old.
Warning drivers to expect significant delays, the state is encouraging motorists who do not need to get on or off in the Medford area to consider public transportation or skirt the affected area using Interstate 95 or other roads. The work site is in the path of thousands of
To forewarn motorists, the Department of Transportation has planted dozens of flashing message boards along the I-93 corridor and on other major roads to broadcast real-time conditions for the highway ahead, based on radar sensors and other methods for evaluating traffic. It is also directing people to consult the project website, 93fast14.com, or call the 511 traffic information line.
The state is also attempting to smooth travel over alternate routes that will carry spillover traffic, including retiming lights on Route 28 and postponing a Tobin Bridge lane-painting project. And it has worked with the Sox, Bruins, and performance venues to broadcast advisories to ticket holders.
The I-93 bridge replacement is drawing national attention for its ambitious timetable and use of precast elements, including hundreds of 60- and 80-foot-long blocks of concrete and steel fabricated in New Jersey and hauled in by flatbed truck, each section weighing 80,000 to 100,000 pounds.
Under the traditional method, rickety highway bridges are chipped away and rebuilt in place, a lane or two at a time, woven out of individual steel beams and rods later encased in concrete. That could consume four or five years for 14 bridges and require equipment to remain in place at all times, even during weekday rush hours, state Secretary of Transportation Jeffrey B. Mullan said.
Instead, all eight highway lanes will remain open on weekdays, but half will be closed from 8 p.m. Friday to 5 a.m. Monday on summer weekends through August, with a break only for the July 4 weekend. Each bridge is slated to be closed, demolished, rebuilt, and ready for traffic in a single 55-hour span, a choreographed sprint involving 100 construction workers and a battery of heavy equipment.
“We understand it’s temporarily disruptive, but as compared to several years that this project could take, I would take the quick delivery any day,’’ Mullan said.
Christine Mizioch, the state’s project manager, likened it to “trying to change the oil in a car while the engine is running,’’ when she presented the contract to the Department of Transportation’s board for approval in February.
The $91.1 million deal, a combined design and construction contract awarded to J.F. White Co. and Kiewit Corp., includes penalties of up to $1.15 million per week on any Monday in which the highway is not restored by 5 a.m., with the penalties starting at $450,000 for even a one-minute delay. However, White/Kiewit could earn $7 million in incentives for meeting all weekly deadlines.
The Department of Transportation had intended to put off the Medford construction for a few more years, trying to squeeze some extra life out of spans that date to the birth of I-93.
But during a routine paving project last August, a couple of gashes large enough to swallow a car emerged, causing multihour delays for tens of thousands and revealing more decay than expected in the steel and concrete below the asphalt.
So the state accelerated plans to replace the bridges that carry the highway over local roads in Medford. The state hopes the replacements will last 75 years, and engineers say the precast elements are just as sturdy as traditional construction. The methods have been tried selectively in Massachusetts and other states, but not on this scale or on such an aggressive timetable, Mullan said.
In July, the state will host leaders from other state transportation departments and from the federal government to observe the replacement of the two southbound bridges over the Salem Street (Route 60) rotary. It is also documenting each replacement, using solar-powered overhead cameras to create time-lapse videos.
In addition to potentially reimbursing 80 percent of the cost, the Federal Highway Administration has awarded the project a $1 million grant under a program known as Highways for LIFE, intended to encourage innovative techniques that yield faster construction and safer work zones.
The timetable calls for one or two bridges to be done per weekend through Aug. 15, a cushion that will allow the project to be stretched through August in the event of prolonged electrical storms or other construction disruptions.
But the timing for each bridge is the same: At 6 p.m., police will close the local road underneath to allow crews to get into place. At 8 p.m., the state will close two lanes in each direction and then divert traffic from the side where the bridge is being rebuilt to the other side of the highway, using a zipper barrier similar to the one on the Southeast Expressway. That will narrow I-93 to two lanes in each direction between exits 28 and 35, roughly between Medford’s Stoneham and Somerville borders.
Demolition begins at 10 p.m. and is expected to last until dawn Saturday, using multiple trucks that resemble a brontosaurus, each with a stout body, a long neck, and a jaw that chews up steel and concrete. Large cranes will then hoist the precast sections — 18 for most bridges, 21 for those over the Mystic River — into place over the course of 12 to 14 hours, with workers linking together the steel bars that extend from the ends.
Concrete will then be poured over the connecting sections to reinforce and secure them, from about 2 to 10 a.m. Sunday. The remainder of Sunday is devoted to curing and testing the concrete, using a mobile lab parked on site, before striping the surface and installing temporary barriers by Monday morning. An asphalt finish will not be applied until after Labor Day.
As the clock ticked closer to the start of the project yesterday, Mizioch, the manager of the state’s highway design-build program, explained the process at the site of the first replacement, over Riverside Avenue.
New concrete support pillars and abutments were already in place below the deck; above deck, the bridge had been torch-cut to ease demolition. But otherwise it was the same bridge that had been there since the dawn of the interstate highway era.
If all goes according to plan, by this morning it will be gone, the new one all but done by tomorrow night.
“And just like that,’’ Mizioch said, “we’ll have replaced a bridge.’’
Eric Moskowitz can be reached at email@example.com.