BY ROBERT MAYNES
In the early morning hours of July 10, 2009, vacationers and commuters attempting to escape from Long Island were presented with an astounding image: Fifty feet of flames originating approximately 10 feet below and extending 40 feet above the roadway of the Throgs Neck Bridge (TNB) were visible from the westbound Cross Island Parkway, just past Fort Totten in the New York City borough of Queens. By the end of that day, more than 300 first responders from multiple agencies had worked to prevent the loss of the bridge. For 30 days, motorists were significantly impacted. If not for the professional tactics employed by first-alarm units, damage to the bridge would have been immeasurable. The potential for injury and loss of life was eliminated by adhering to the tactics, procedures, and professional leadership of Fire Department of New York (FDNY) supervisors.
|(1) The view from the bridge looking north from the Bronx-bound roadway after the main body of fire was knocked down. Note the netting extending from the fire area to midspan. (Photos courtesy of Firefighter Dave Raynor, Rescue 1, Fire Department of New York.)|
The Throgs Neck suspension bridge was completed in 1961 after four years of construction at a cost of $92 million. The 5,200-foot bridge spans the mouth of the East River from Bayside in Queens to Throgs Neck in the Bronx, New York, by way of an easement through SUNY Maritime College in Fort Schuyler. The two approaches add 6,700 feet of roadway, for a total of 11,900 feet. The TNB was designed with a 28-foot-deep stiffening truss and is elevated 142 feet above the East River at its high point. The bridge services an average of 105,000 vehicles each day and is a vital transportation link between Long Island and several roads, including Interstate 95. The Triboro Bridge and Tunnel Authority (TBTA) services and enforces the bridge. The roadway consists of six lanes; the eastern span serves northbound travelers to the Bronx, and the western span serves southbound travelers to Queens. Toll booths are on the Bronx mainland.
On July 10, 2009, overnight crews were working below the Bronx-bound span in the area approximately 700 feet from the Queens mainland. The depth of the water below the construction was five feet. Scaffolding constructed of Q-decking supported by steel cables, which sat six feet below the bottom of the bridge support beams, provided access to the bottom of the bridge for the roadway workers.
The bridge supports were substantial I-beams that framed a truss. The I-beams are constructed in lengths supported by columns. Debris and waste produced by maintenance cannot be permitted to fall into the East River because of the environmental impact. To prevent any loose debris from falling into the water, the bridge contractors constructed a wood deck by laying wood lengths side by side between the webs of the I-beams. Additionally, protective netting spanned approximately 500 feet of the scaffolding, extending 10 feet from the top of the roadway to below the scaffolding (photos 2, 3).
|(2 Suppression resources operating in the scaffold area. Note the suspended cables supporting the scaffold from the main structure.|
|(3) The engine company operating in the scaffold area is using the reach of the stream to suppress the fire.|
The netting and the deck provided for personal and environmental safety. The netting and construction material introduced a serious fire load to a steel structure. The combination of the flame, fuel load, and inherent heat while burning endangers the stability of steel. The late Francis L. Brannigan commented extensively in his book Building Construction for the Fire Service on the potential for damage to steel bridges, particularly suspension bridges similar to the TNB.
As a precaution, a standpipe was included in the TNB construction and is fed by engine companies assigned to Fort Schuyler at the Bronx end of the bridge. A standpipe outlet for fire suppression is at the top of the main span. FDNY is cognizant of the potential for extensive damage to bridges. We have preincident guidelines for suspension bridges, and first-alarm units conduct familiarization drills. Companies are assigned early in the alarm to support suppression tactics on all New York City suspension bridges. Brannigan praised FDNY for prioritizing protection of steel suspension bridges because of the potential for extensive damage from fire. Cooperating agencies not familiar with the fire potential often choose not to conform to the fire service’s recommendations.
AT 0430 hours on July 10, construction workers were using MAPP gas to support TNB maintenance operations. MAPP is a liquefied petroleum gas mixed with methylacetylene-propadiene. The incipient fire accidentally started in the scaffolding area approximately 350 feet from the Queens entrance to the Bronx-bound TNB. Initially, construction workers had attempted to extinguish the fire with hand extinguishers. These attempts, which resulted in a delay in contacting emergency first responders, hindered FDNY operations. The fire, fed by a 10 mile-per-hour (mph) northeast wind rapidly intensified and extended to all exposed materials, including the netting and platform. As the fire progressed, two 100-pound cylinders containing an estimated 140 pounds of MAPP gas were exposed. A subsequent boiling-liquid, expanding-vapor explosion (BLEVE) occurred. The BLEVE intensified the fire and created two approximately six- × six-foot-diameter holes in the Q-decking. Subsequent investigations by the FDNY Bureau of Fire Investigation concluded that an excess of 50 pounds per square inch (psi) of pressure was required to damage the Q-decking. Additionally, the fire intensified to a minimum of 1,600°F. The temperature would have exceeded 2,000°F, but it was reduced by the venting of flames to the open air above the roadway. Steel will sustain damage at any temperature over 1,000°F.
At 0500 hours, when commuters were crossing the bridge, the fire was severely impacting its stability; a collapse or permanent loss of the bridge was highly possible. Additionally, subsequent extension to the three lanes of the Queens-bound span was inevitable. Fortunately, all construction workers had exited the bridge prior to the BLEVE. The financial impact of catastrophic damage to the bridge is unfathomable. First-alarm units were confronted with a complex operation that would require discipline and outside-the-box decisions. Queens Engine Company 295 arrived first. Signal 10-75, a report of a working fire requiring a full first-alarm assignment, was promptly transmitted. Bronx Special Operations Ladder Company 50 responded southbound.
Battalion Chief Dennis Crichton of Battalion 52 arrived at the incident shortly after the initial companies. On his arrival, there was an unconfirmed report from construction workers that all workers had evacuated the bridge. Engine 295 had initiated the task of supplying a handline. A straight ladder was used to gain access to the Q-deck scaffold under the bridge. Crichton’s size-up included an advanced fire in an undetermined area below the bridge roadway. The fire was increasing in intensity and moving northerly toward the midspan. The extent of damage to the structural steel of the bridge was unknown. Initial reports listed no civilian life hazard, which caused the suppression resources to be identified as the primary life hazard. FDNY marine resources took 30 minutes to arrive. The stability of the access path below the roadway to the fire area was questionable. Suppression efforts were needed to stop the potential loss of millions of dollars and extended reconstruction.
Crichton delayed the use of the access portable ladder until a chief officer conducted an investigation. At this time, Battalion Chief Lawrence Cleary, Battalion 53, arrived at the incident command post (ICP) established on the bridge, north of the fire. Cleary descended the ladder and discovered the Q-deck scaffold. Additionally, the portable ladder terminated on a girder supported by the columns anchored below the water. The girder area served as an anchor point for suppression resources. Cleary determined that an aggressive attack with a handline supported by a ladder company was necessary to minimize exposure to the steel below the bridge. Ladder Company 50 was trained in technical rescue tactics and supported Engine 295’s attack on the fire under Cleary’s direct supervision.
Battalion 53, serving as the Fire Area Division supervisor, directed Engine Company 295 as it started knocking down fire in the open area between the Q-deck platform and the underside of the bridge roadway. Engine 295 advanced out onto the platform, extinguishing the main body of fire using the reach of a 2½-inch stream. Damage to the Q-deck scaffold prevented an advance to the main body of fire. With the main body of fire knocked down, a complex complete extinguishment operation was needed. Supplying water to handlines needed below the bridge proved to be a complex operation.
The standpipe outlet located midspan of the TNB was 1,800 feet from the access ladder and would require more than 36 lengths of 3½-inch supply hose to reach it. The effectiveness of the long supply line would have been reduced because of the initial engine’s feeding a standpipe 142 feet below the outlet on Fort Schuyler. Hydrants on the Queens mainland were significantly closer. Battalion 54 Chief John Maguire was assigned as Water Supply Group supervisor. Ten companies were assigned to lay 16 lengths of 3½-inch supply line. Simultaneously, six engines served as water tenders, maintaining Engine 295’s booster tank while additional companies stretched the 3½-inch supply line. Battalion 52 transmitted a second alarm at 0540 hours.
I arrived as Division 13, completed a transition of command with Crichton, and assumed the position of incident commander (IC). Crichton now served as Operations Section chief. Battalion Chief 50 Paul Tauber arrived at the ICP on the second alarm and relieved Battalion 53 as Fire Area Division supervisor. At this time, the extinguishment line below the bridge had progressed as far as was safely permitted with current tactics. Additional extinguishment with a handline would necessitate a rope, wire, or cable with all resources hooked to the safety line. Engineers from the TBTA, who had been requested, were responding to assess the scaffold’s stability.
The main body of fire was significantly reduced. Fire was burning in the wood deck and void between the webs of the bridge’s I-beams. Extensive overhaul operations from the questionable Q-deck scaffold were now needed to access the fire. The complexity was increasing as the tar on the roadway was bubbling from the concealed fire below. The fire over the Q-deck scaffold was intensifying in the area to the north of and beyond the BLEVE area.
Marine Company 6 was now on the scene in the East River below the fire area. The water supply operation was completed. An East River Division was established, and Maguire assumed the position of Division supervisor on Marine 6’s support boat. Intelligence gathered by Marine Company 6 concluded that the five-foot depth in the operation area would eliminate the use of Marine Companies 1 and 3, since they were larger than Marine Company 6 and required a nine-foot draft.
All resources were moved from the Q-deck platform area and the exposed area on the roadway above the fire. Marine Company 6 directed its stream from the East River at the platform and the debris deck (photo 4). Access was reduced; the Q-decking of the scaffold blocked the stream from directly striking the underside of the debris deck. Marine Company 6 positioned its vessel at an angle that would maximize the application of water, and the fire volume and heat were significantly reduced.
|(4) Marine 6 delivers a large-caliber stream to the scaffold area. Note the protective netting extending from the fire perimeter to midspan.|
The handline stream followed by the large-caliber marine company stream knocked down the majority of the fire, and the temperature of the steel returned to normal. Fire was still smoldering in the debris deck between the roadway and the debris platform. The fire condition was the equivalent of a deep-seated smoldering cockloft fire without the stability of a sturdy floor below for operating personnel. Hooks were not adequate for exposing the fire. Specialized 16-inch saws with alpha diamond blades manufactured from diamond dust were used (photo 5). After the wood deck was cut, the boards were manually removed and stored in a safe place on the scaffold.
(5) Firefighters from Rescue Company 3 use a saw with an alpha diamond blade to cut the decking constructed between the I-beam webs to expose smoldering fire.
Special Operations Group Supervisor Chief John Spillane was assigned to oversee the final extinguishment. Deputy Assistant Chief John Sudnik arrived and was assigned as the Command chief. Later in the operation, Chief Joseph Downey relieved Spillane as Group supervisor. Rescue Company 3, with support from Squad Companies 288 and 270, constructed a line made from half-inch kernmantle rope from the original girder area to a secure anchor toward midspan. All suppression forces hooked themselves into the kernmantle rope and worked from the safety line. Tethered squad company personnel extinguished the fire with a handline. The special operations companies used the alpha diamond blade to cut the wood debris deck and expose the smoldering fire. The companies progressed to the BLEVE location and halted operations based on information provided by the structural engineers. Eventually, under the direction of the Special Operations Group supervisor, a wire rope was anchored on both ends of the fire area and served as a lifeline, increasing responders’ safety. Extinguishment was concluded at 1459 hours. Special Operations used the services of two rescue companies and four squad companies in addition to the third-alarm assignment.
The Bureau of Fire Investigation had to investigate the incident in view of the extent of the damage. After Downey trained the assigned fire marshals in how to use the wire rope system, the investigation began. Structural engineers also investigated the extent of the damage.
At 1400 hours, all cooperating agencies agreed to open the Queens-bound span. The Bronx-bound span needed 30 days of repairs before traffic could be fully restored northbound. Traffic conditions were significantly impacted; commercial vehicles incurred extensive delays. Two lanes of the Bronx-bound span were partially opened the evening of July 10, 2010, to passenger vehicles only. Access to the Bronx-bound TNB was minimized to two lanes; access was limited to the Clearview Expressway. The Cross Island Parkway entrance remained closed for 30 days.
Structural steel will start to expand at 1,000°F. The exposed steel of the TNB sustained significant damage at 1,600°F. The cooling of steel by applying water will return steel to its original shape, but the steel will be weakened and has to be repaired or replaced. The TNB’s structural steel had to be repaired and replaced. Since the investigation is ongoing, the exact amount of damage to the TNB has not yet been released.
The successful tactics used in this operation prevented significant injuries to the public and responders and the potential loss of millions of dollars. Had the bridge partially collapsed, it would have had to be closed for an unspecified time and would have had a significant adverse impact on traffic.
CHALLENGES AND LESSONS LEARNED
- Risk Assessment. Life is the priority for all FDNY operations. At the TNB third alarm, reasonable reports included the absence of a civilian life hazard. Early in the operation, bridge traffic was stopped for all but first responders. Left to burn, the fire could have led to partial collapse of the bridge and significant financial loss. The initial IC weighed the reward and directed minimal exposure under the close supervision of a chief officer serving as division supervisor. Marine company streams were not started until all individuals were removed to a safe zone. Special operations were conducted under the direct supervision of a qualified technical rescue group supervisor. Special operations were delayed once stability was questioned and additional precautions focused on safety were implemented. An appropriate amount of time was included in decision making based on increased situation awareness.
- Subject Matter Experts. Early in the operation, the IC requested that individuals experienced in bridge maintenance and construction serve as technical specialists. Assistance was needed in determining if it was possible to operate below the bridge. Technical information was needed to determine the capacity of the platform for suppression efforts. Individual engineers provided conflicting information. Timely information was not forthcoming, and there was confusion relative to the impact of the fire and the BLEVE on the Q-deck scaffold. Once significant extension was accomplished, the decision was made to remove suppression resources until the wire safety line was completed.
- Marine Company Operations.The use of large-caliber marine company streams can be of immense value. Marine Company 6’s stream extinguished significant fire, culminating in a reduction of exposure to personnel in a dangerous location. The East River under the fire area was limited to a five-foot draft. Marine Company 6 was able to position the vessel and move the stream for maximum benefit. In addition, Marine Company 4, a seasonal two-firefighter boat, responded and served as a support vessel and a safety vessel. A division supervisor assigned to the marine vessel maximized communication and coordination. If available, a technically trained marine company officer is qualified for this assignment.
- Investigation. Bureau of Fire Investigation fire marshals were required to investigate the area between the roadway and the Q-deck scaffold. They determined that only qualified technical rescue firefighters could operate in the area. In consultation with the Special Operations Group supervisor, the IC decided that the fire marshals would be trained in the basic use of operating while hooked to the wire rope. The Group supervisor closely supervised the entry, and additional qualified technicians accompanied the investigators to increase safety. FDNY Chief of Operations Robert Sweeney and Chief Fire Marshal Robert Byrnes were consulted by phone and approved the plan. The combined fire investigation technical rescue crews completed their investigation. At the time this article was written, the investigation was still ongoing.
- Hazardous Materials. The presence and potential of any substance to explode, BLEVE, or have a flammable reaction must be included in size-up. Fortunately, the BLEVE occurred prior to the arrival of fire resources and after the evacuation of construction workers. It was determined that the approximate 140 pounds of MAPP gas was not being used properly. FDNY inspectors’ authority to enforce the codes/laws on the TNB is nebulous. First-arriving units and chief officers need to ask credible representatives at construction projects if hazardous materials are present.
- Water Supply. FDNY engine companies were confronted with a significant fire in an inaccessible location. A dry standpipe was located 1,800 feet to the north. A hydrant was located 700 feet to the south. Extinguishment efforts would require thousands of gallons of water, far surpassing the capacity of a 500-gallon booster tank. A complex water supply operation requires the cooperation of all engine companies striving to maintain a constant supply of water for engaged resources. At the TNB, third-alarm simultaneous complex supply operations were employed. Six engine companies served as nurse engines maintaining Engine 295’s booster tank. Ten companies completed the arduous task of establishing a 3½-inch supply hoseline with a hydrant as a source. At the TNB fire, a Water Supply Group was established, which resulted in a successful water operation
- Critique.Two weeks after the third-alarm, supervisors from appropriate units participated in a formal postfire critique. Through discussion, all involved increased their knowledge of the actions performed. Recommendations were offered to improve tactics and prevention strategies on suspension bridges. The critique continues to be a valuable educational tool.
ROBERT MAYNES is chief of planning and strategy for the Fire Department of New York (FDNY) and the incident commander of the FDNY Incident Management Team. At the time of the Throgs Neck Bridge fire, he was a deputy chief assigned to Division 13 in South Queens.
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