FRIDAY, DECEMBER 23, 2022
Yesterday (Dec. 22), officials opened the new Fern Hollow Bridge, after the construction of the replacement structure was completed less than a year after the original bridge’s collapse in January. The bridge is currently open to a single-lane of bi-direction traffic.
A ribbon cutting ceremony was hosted earlier this week while line painting and other finishing touches continued on the $25.3 million bridge.
“This is the best Christmas gift we could give the city of Pittsburgh,” said Mayor Ed Gainey as he stood on the newly built bridge at the event.
The opening, however, arrives just as the new Comprehensive Bridge Asset Management Program released a report, highlighting structural issues with dozens of bridges maintained by the city that should be addressed within the next six months.
Fern Hollow Bridge Collapse
On Jan. 28 around 6:40 a.m., the Allegheny County Police Department was notified about a partial bridge collapse over Frick Park. Emergency crews arrived at Forbes Avenue Bridge, also referred to as the Fern Hollow Bridge, around Forbes and Braddock avenues.
Initial reports indicated that an articulated Port Authority bus and four passenger vehicles were on the bridge at the time of the collapse, along with a fifth passenger vehicle that drove off the east bridge abutment following the collapse. First responder crews rappelled 100 to 150 feet to reach victims, while others formed a “human chain” to rescue people from the bus.
A preliminary NTSB investigation reported that the bridge was an uncoated, weathering steel, three-span, continuous rigid “K” frame structure with two welded steel girders, welded steel floor beams and rolled steel stringers. The ends of the structure rested on reinforced concrete caps on stone masonry abutments, with each girder additionally supported by two inclined, welded and uncoated weathering steel frame legs on concrete thrust blocks.
According to the release, certain areas of the welded steel girders were identified as being fracture critical, but no primary fractures were found in those areas. Initial assessment indicates the collapse began at the west end of the bridge.
The Fern Hollow Bridge has reopend to all traffic 11 months after it collapsed. https://t.co/t30mMri014
— WPXI (@WPXI) December 22, 2022
In May, the NTSB provided an update on the recovery of structural components and tests currently being conducted to evaluated materials used when constructing the bridge, as well as a review of new footage recovered from a transit bus camera system.
Investigators reviewed video footage from the time of the collapse from two of the cameras on a Port Authority transit bus. The cameras, one forward-facing and one rear-facing the curbside, were determined to have “investigative value” with frames depicting events of interest.
The first frame, from the forward-facing camera, reportedly shows the bridge deck separating at the east expansion joint. The second frame, from the curbside camera, reportedly shows that, at nearly the same time, the west end of the bridge had already fallen off the west abutment.
Additionally, while the preliminary report listed ten vehicle occupants as being injured during the bridge collapse, further investigation has confirmed a total of nine occupants in six vehicles, including the Port Authority transit bus. Of the injuries, two vehicle occupants sustained serious injuries, two injuries were minor, four were uninjured and the injury status of one is unknown.
That same month, a newly released inspection document revealed that the Fern Hollow Bridge had “major decay” prior to its collapse, including exposed rebar, corrosion, holes in the steel cross-beams and spalling in the bridge deck.
The Pittsburgh Post-Gazette obtained a partially redacted copy of the October 2021 inspection report from the Pennsylvania Department of Transportation in response to a Right to Know request. In the 106-page document, a section under immediate improvements needing prompt action listed “none.”
The 26-ton weight limit from 2014 was also kept after the inspection, with the report citing that “because the condition of the main load carrying members has not changed significantly, the 2014 Load Rating Analysis is still valid.” However, sections regarding the data that led to that original weight limit were reportedly redacted by PennDOT.
In the report, eight short-term, Priority 2-level improvements were included, with the most expensive being “repair spalled and delaminated concrete underside” for $160,000. Seven Priority 3 recommendations were also noted, including “upgrade bridge rail to current PennDOT standards” for almost $178,800.
“The remaining cross bracings are in poor condition. The cross-bracing exhibit uneven weathering, laminar rust, severe corrosion and holes in webs at bracing connections,” stated the 2021 inspection report. “The cross bracing is deteriorating due to malfunctioning drainage systems in addition to deterioration, contamination and seepage through the deck concrete (previously noted).”
Additionally, the steel legs reportedly showed significant deterioration, being in “poor condition,” some stiffeners exhibiting 100% section loss and “laminar rust and holes in the web.” Up to 50% section loss was seen on the bolts on the inside of a girder splice plate connecting the west end of the bridge to the central portion.
Inspectors also found spalling on the underside of the concrete bridge deck, with water seeping from the top of the deck through to the steel below. This, inspectors believed, was caused by chlorides from winter salt.
Replacement Design Plans
In March, PennDOT announced design and construction plans to replace the bridge, in collaboration with City of Pittsburgh officials and the Federal Highway Administration. PennDOT selected HDR Inc. and Swank Construction Company to design and construct the new bridge. The Design Build partnership also took environmental complexities into account regarding its location with Frick Park.
According to the release, the team determined after evaluating several options that a three-span continuous composite prestressed concrete I-beam with integral abutments would be the best structure type. Material availability, cost, design concerns and delivery time, along with supply chain concerns, were factored into the decision.
The new structure remains along the same roadway alignment and width, but included plans to include four 10-foot-wide travel lanes, two-foot-wide shoulders on both sides, a five-foot-wide sidewalk and a 10-foot 5-inch-wide shared use path on the southern side of the bridge.
Aesthetic treatments planned also included treatments to the concrete pier columns and bridge barriers, painting of the beams, a stream restoration plan, ornamental bridge lighting and a site restoration plan with tree plantings to restore damaged areas. PennDOT consulted with Pittsburgh Parks Conservancy and the Pittsburgh History and Landmarks Foundation and sought public input on these elements.
Emergency declarations issued following the collapse reportedly allowed the city and PennDOT to manage construction and design for the project immediately, while also using emergency procurement procedures through the FHWA to being work within seven days of the collapse. These emergency procedures allowed the replacement to occur two to three years earlier than would have been possible using typical design and construction methods.
Construction began in May for the $25.3 million replacement bridge with the pouring of concrete for the first caissons to support two sets of columns that look like double capital Ts. The previous bridge had steel supports at each end. The 150-foot-long concrete beams were delivered at the end of July and into August.
At the end of September, crews began pumping concrete to create the deck for the new bridge. Work was expected to take between three and four weeks to complete, with additional curing time. Overall, 1,500 cubic yards of concrete was poured.
Fern Hollow Completion, Bridge Report
According to a press release, the substructure, superstructure and concrete deck placement work has all been completed, with bridge deck overlay and wingwall work occurring until next spring. Bridge barrier installation, pedestrian railing and line painting are anticipated to be finished by late December.
Around 1:30 p.m. on Thursday, the bridge reopened to a single-lane of bi-direction traffic. The southern side of the shared use path is also open to pedestrians and bicyclists. The reopening reportedly occurred a day earlier than anticipated due to an incoming winter storm in the area.
“I was here on January 28 to survey the damage from the collapse, and today, less than a year later, I stand before a bridge that is nearly ready to reopen to traffic,” said Pennsylvania Governor Tom Wolf. “This is the power of government working for the people in Pennsylvania.
“I’m thankful to all of our partners in state, local and federal government for your partnership and coordination to rebuild the Fern Hollow Bridge in less than a year. It’s an honor to be here to celebrate this incredible milestone for Pittsburgh.”
We are thankful for @POTUS, @GovernorTomWolf, @PennDOTNews, @PGHDOMI, and everyone here today who worked to bring back the Fern Hollow Bridge.
— Ed Gainey (@gainey_ed) December 21, 2022
This is what “let’s go get it” looks like in reality. pic.twitter.com/iEik6VpEDi
“This new bridge is the result of incredible collaboration,” said PennDOT Secretary Yassmin Gramian. “And thanks to the federal investment through the bipartisan infrastructure law, we were able to quickly mobilize to rebuild this bridge without impacting funds for other important projects.”
In addition to the ribbon cutting ceremony, a report from the Comprehensive Bridge Asset Management Program was released to provide an accurate report on Pittsburgh’s bridges. The program had been launched this spring following the collapse of the Fern Hollow Bridge.
Local engineering firm WSP, which was unanimously approved a $1.5 million, two-year contract to inspect and evaluate all city-owned bridges in July, conducted inspection reviews of 147 bridges.
“When Fern Hollow Bridge came down, I knew that we had work to do to understand the condition of our city owned bridges, to make needed repairs, and to instill confidence in our infrastructure,” said Mayor Gainey in a statement.
“This report of the Bridge Asset Management Program is intended for everyone to understand the state of all 147 city owned bridges. I would like to thank the team from WSP who worked diligently to prepare this report for our city.”
The report cited that 27 bridges needed to see some type of work done almost immediately and were designated as “critical” in terms of when updates should be done. Of those,Gainey spokeswoman Maria Monataño said that 14 were related to signage issues, such as updating posted weight restrictions.
The report said 13 spans had structural issues that needed to be addressed within seven days. Issues have been resolved at 10 of those bridges, the report said. Those bridges were reportedly not identified by name.
Additionally, 69 “high-priority” bridges need to be addressed within six months, with four of those having signage issues and 65 with structural issues. Five of those structural issues were reportedly resolve, along with one signage issue.
WSP reported that 18 bridges, including eight for vehicles and 10 for pedestrians, should receive an additional inspection to gather more in-depth information about the spans.
According to the City of Pittsburgh's press release, the response to the findings has been proactive, initiating and completing repairs on a rolling basis. The next phase of the project with WSP involves the development of a comprehensive asset management plan.
“When we announced this program I made a promise to the people of Pittsburgh,” continued Gainey. “I would not hesitate to close a bridge down if it was found to be unsafe. Safety of the people who live and work in our city is our number one priority and we will continue to do the work of keeping our roads and bridges safe for everyone.”
The full report can be viewed here.
Tagged categories: Bridges; Bridges; Construction; Government; Government contracts; Health and safety; Infrastructure; Infrastructure; Inspection; Ongoing projects; Program/Project Management
