PORTLAND — Saw, lift, dump.
Those are the four steps to demolition of the old Martin’s Point Bridge, summarized by CPM Constructors field engineer Jake Hall.
“We are getting a span or two a day,” Hall said Sept. 2 as he walked on the new bridge spanning the Presumpscot River between Portland and Falmouth. “I would like everything to be done by mid-November.”
The near-completion of the new bridge will be celebrated with a free, public “Bridge Bash” event from 1-4 p.m. Sunday, Sept. 14.
The party will be on the new bridge’s multi-use path, near the campus of Martin’s Point Health Care on the Portland side of the bridge.
Construction project spokeswoman Carol Morris said Sept. 2 the celebration will be “a family-oriented event that centers around transportation options on the bridge: biking, walking and driving.”
Sponsored by the city of Portland, town of Falmouth and Martin’s Point Health Care, the event will feature food trucks, live music, antique cars, face painting, glitter tattoos, a used book sale and an apple pie bake-off.
Visitors will also be able to view photos of bridge construction and get an up-close look at construction equipment used in the $23 million project.
About 10 feet below and north of the new bridge, skeletal remains of the 72-year- old, 1,400-foot, steel-and-concrete span are being cut away by 20 workers in 260-square-foot sections.
Morris estimated the cost of removing the old bridge at $1.6 million, or about 7 percent of the cost of the entire project that began two years ago. The new bridge opened to pedestrian and bicyclists June 2, and to vehicular traffic on June 13.
Finish work on the new bridge is continuing, but the greater focus is now on dismantling the old bridge and saving as much of it as possible for re-use elsewhere, Hall said.
“The steel’s in good shape, the deck is in good shape, so are the wood pilings,” he said.
To do the job, water-cooled, diamond-edged saw blades cut through the old concrete. Torches pierce steel girders, cranes lift sections weighing 10 tons or more, and heavy hammers break up the concrete.
Once a section is cut away from the bridge structures, it is hoisted over the water and swung back on the remaining deck, with crews working backwards from the center of the old bridge.
The section is then broken apart, and concrete chunks are dumped into barges. One barge also holds a crane needed for work over the water.
Hall said the initial challenge was putting the deconstruction steps together, and scheduling around tides.
“At least you know when the tides are going to be. A little planning goes a long way,” he said.
Above the water, the wooden pilings show the age and wear of eight decades of salt water and weather. Hall said they are in remarkably good shape, with creosote coatings looking as fresh as when they were applied to the pilings that were pounded 40 feet below the ocean bottom.
The salvageable pilings will be reused in the Portland area, Hall said. The steel will also be recycled locally, and the concrete will be reused as fill. Even the metallic rebar ribs inside the concrete have been separated for recycling, and railings from the old bridge were installed on the new span.
The new span is actually about 120 feet shorter than the old one because more fill was used for the bridge approaches from Veranda Street and U.S. Route 1. Hall said pilings are set in bedrock, about four times deeper than on the old bridge.
The new bridge was designed by Vanasse Hangen Brustlin, a Watertown, Massachusetts-based engineering firm, and the CPM bid was one of five received for the project.
CPM Constructors field engineer Jake Hall said Sept. 2 that demolition of the 72-year old Martin’s Point Bridge has progressed smoothly. “I would like to see everything done in mid-November,” he said.
George Tuttle IV of CPM Constructors cuts through a steel girder Sept. 2 on the old Martin’s Point Bridge. Crews are trying to reuse as many of the bridge elements as possible.
A 26-by-10-foot section of the old Martin’s Point Bridge is hoisted away Sept. 2.