Cover Story: A Narrow Place, A Great Bridge
The final cable stay has been pulled through its housing on the Verona pylon, and crews have poured concrete for the final section of deck joining the Prospect and Verona halves of the bridge. Crews are at work on the bridge, that has been under construction by Cianbro- Reed & Reed LLC since December 2003, getting ready for its first public unveiling on October 14. That is the day the bridge will be open to pedestrians for a “sneak peak.” Drivers will have to wait until sometime in November or December to test their wheels on the new bridge. The observation tower will open in the spring of 2007.
Meanwhile, the new span already is garnering attention from bridge watchers around the world. Road & Bridges magazine put it at the top of its Top 10 list — the bridge builder’s equivalent of People magazine’s Best Dressed list. The Federal Highway Administration has recognized the project for its innovation. The design features many industry “firsts,” and local businesses and citizens are praising the new structure and the role that it promises to have in the region’s economy.
Design-build on steroids
During the fall of 2003, there was a very real sense of urgency that a new bridge had to be built — and quickly. An inspection earlier in the year had discovered that the corrosion had compromised the steel suspension cables supporting the old bridge, and engineers were not sure that the old bridge could be repaired cost effectively. The Waldo-Hancock Bridge was posted to prohibit vehicles weighing in excess of 24,000 pounds while engineers developed an innovative supplemental cable system. While the old bridge with temporary repairs reopened to traffic weighing up to 80,000 pounds later that autumn, the need to put up a new bridge quickly necessitated what one contractor has called “design-build on steroids.”
MaineDOT selected Figg Bridge Engineers to design the bridge and awarded the construction contract to Cianbro/Reed & Reed — a joint venture of two of Maine’s largest construction firms. MaineDOT and Cianbro-Reed & Reed LLC broke ground on the new bridge in December 2003. Due to the nature of this fast-track design build project, “almost everything on this bridge has been ‘just in time delivery,’” said Kaven Philbrook, MBTA board member and Cianbro/Reed & Reed’s project manager of the unusually high-profile, high-pressure project. The race to complete the bridge meant crews began work on the bridge footings before the design had been finalized. The preliminary design did not have an observatory or an elevator and these two additions were unprecedented, so for “most of this job we have been just one step ahead of ourselves,” according to Philbrook.
Even now, as contractors put the finishing touches on the bridge deck, the engineers, suppliers and contractors are wrangling with the added complexities of meeting necessary codes for public access of the Prospect pylon. “Building a bridge is one thing, but this one has a whole different set of rules,” said Philbrook. Philbrook cited the challenge of procuring safety glass for the three floors of panoramic windows in the observation deck that at 420 feet above the ground must withstand high winds. Just a month before the first public unveiling, Cianbro/Reed & Reed just confirmed that a supplier in Toronto had successfully completed wind load testing on the material, so the three floors of glass panels can be delivered within the next few weeks.
A funding highpoint
Meanwhile, the state was left to figure out how to pay for the new bridge. A mid- 1990s feasibility study had estimated replacement costs at around $55 million. MaineDOT Project Manager Tom Doe is a long-time veteran of bridge construction who had planned to retire before this project came along. He described that estimate as one made in a best case scenario. “Those were mid- to late 1990s dollars and those dollars would have been estimated predicated on a normal construction sequence with a complete set of plans and a competitive bid where the contractor was not bidding the risk,” said Doe. But the discovery of the old bridge’s dire condition had caught MaineDOT off guard and without enough money in the state’s coffers to pay for the replacement.
The emergency situation encouraged MaineDOT and the legislature to try a new form of financing — Grant Anticipation Revenue Vehicle or GARVEE bonds — to help pay for the bridge
replacement. GARVEE bonds allow states to borrow money against anticipated federal fuel tax revenues. In the case of the Penobscot Narrows Bridge, the state did not have enough funds to cover the total bridge cost and all of the current federal funding had been allocated to other projects. The legislature passed a bill to approve up to $50 million in GARVEE financing for the bridge. Governor John Baldacci signed the bill into law in April 2004.
Initially, MaineDOT expected the bridge replacement to cost $50 to $75 million. The price tag quickly grew as the project took shape. There were design innovations and the addition of an elevator and observatory tower. The price of construction materials also rose dramatically, and of course, there was the part of the cost that MaineDOT’s Doe attributed to the “go fast” nature of the project.
The price tag now stands at $84 million, a number that, according to Doe, makes sense. Additionally, MaineDOT anticipates spending another $10-$15 million on dismantling and disposing of the old bridge. “If you took that mid-90s estimate and escalate it to 2006, including the additional inflated costs from construction, then back out $5 to $6 million for the observatory cost — I’d be willing to bet that leaves about 10 to 15 percent for the go fast,” said Doe. No green to be seen
While almost everyone gets breathless talking about the new bridge these days, that has not always been so. When the project was in the design stage, there was a major difference of opinion between what the local community wanted and what would meet MaineDOT’s needs for a cost-effective, lowmaintenance structure. Local residents, who were extremely fond of the old green steel suspension bridge, were hoping the new bridge would resemble the old design with the green-painted steel structure that had been part of the local landscape for so many years. Designers and MaineDOT were favoring a cable stay design that would be less expensive to build and maintain and have a longer life.
A turning point came, according to MaineDOT spokesperson Carol Morris, after the second design workshop. “The theme of local granite played such a big role in the design,” said Morris. She said the idea for an observatory evolved from that historical theme and the fact that the Washington Monument in its day was innovative because it incorporated an observatory at the top.
“That observatory really switched things around,” said Alvion Kimball, secretary of the Bucksport Chamber of Commerce and chairman of the BridgeFest Committee, the group organizing the many events celebrating the opening of the bridge. “Ninety percent changed their minds when the observatory was added. That was a big selling point to the community.”
Praise for the crews
Alvion Kimball says that the area residents served by the bridge are overwhelmingly positive about the process of working with MaineDOT, particularly considering the pressure the department was under to fasttrack construction due to the role the river crossing plays in the state’s economy.
“Townspeople, from Searsport to Orland and every town in between, are pretty taken [with the new bridge],” said Kimball. He also is quick to praise the crews that have worked on the span. “We’ve watched these people work on it for the past two years, and it’s been something. They’re out there every day, rain or snow like the Post Office is supposed to be. We have nothing but praise for them.”
That’s not to say that there aren’t skeptics who have been watching the project with a close eye. Recently, as preparations were made to pour concrete closing the gap between the Prospect and Verona sides of the bridge, several residents blogged on the project’s web site, pointing out that the two halves of the bridge weren’t quite meeting in the middle. MaineDOT spokesperson Morris said that the public’s avid interest and involvement in the project through forums like the online blog have in many ways been a blessing for the project.
“This has been a great opportunity to report what’s happening on the site to the public, to answer questions and get accurate information out quickly,” said Morris. She said she would recommend encouraging public input and questions on high visibility projects like the bridge.
Built to last
While bridges built around the time the original Waldo-Hancock Bridge were expected to last for 50 years, the Penobscot Narrows Bridge is part of a new generation that could stand for a century or longer — and reduce maintenance costs in an era where highway funding is a major concern. Figg Bridge’s design for the bridge employs new technology meant to increase the lifespan of the structure and reduce MaineDOT’s maintenance cost. One example is the inert gas monitoring system that will protect the cable stays from corrosion. After the bridge is completed, all of the air in the cable and its housing will be flushed out and replaced with nitrogen at a pressure of two pounds per square inch. That pressure then will be monitored electronically. Any change in pressure will alert MaineDOT that there has been a breech that needs to be repaired.
Figg also incorporated a unique cradle system for the cable stays into the bridge design. The system uses a stainless steel sleeve to carry cable stays through the pylons so one continuous strand can be used from deck to pylon to deck. The sleeves eliminate wear from strand-to-strand contact. Because strands are anchored on the deck, they reduce the tensile forces on the pylons — in a typical design, cables exert a pulling force on both sides of the pylon. An added benefit is that individual strands can be removed and replaced without compromising the integrity of the bridge structure. While Figg had initially developed this cradle system for a bridge in Toledo, Ohio, Maine — because of the speed in which the project has been built — was the first to actually thread a cable stay through a cradle and will be the first site where the technology will be put to test.
The new bridge will also give MaineDOT the opportunity to test the longevity of different kinds of stays. The department plans to replace two of the steel strands in each of three stays with carbon fiber strands, then measure their performance over time, comparing them with their sister steel strands. MaineDOT’s Tom Doe ranks this bridge among the most rewarding built during his long career. It was only his second designbuild bridge, and he is sure that it will be around for a long time. That will be important to the local and regional economy in the future. “Given that we put the right things in place, this bridge could last 150 or 175 years,” said Doe.