By Bryan Hastings and A.D. Vickery
On April 18, 2002, at 1515 hours, a track hoe operator was working on the demolition of a 200-foot bridge connected to a pedestrian walkway that passed 30 feet over a pop-ular running trail in the north end of Seattle. It was being demolished because of irreparable damage it sustained during the Nisqually Earthquake on February 28, 2001.
Track hoes from below on the running trail had removed the center section. Either side of the original walkway had 40 feet of bridge span remaining that had to be removed from street level. At street level, a 22-foot-wide concrete abutment, with steel cable tiebacks, provided soil stabilization.
An experienced 62-year-old heavy machine operator was using his track hoe positioned behind the abutment to remove portions of concrete that were beyond his reach. He then moved the track hoe onto the short span of walkway parallel to the abutment to grab larger sections of concrete. As he swung his boom around and prepared to turn the tracks to leave this area, the walkway collapsed.
VICTIM’S CONDITION
The operator attempted to free himself from the falling track hoe, but his upper body was thrown back into the cab. As the track hoe slid sideways, the walkway detached from the abutment, dropping the track hoe between the abutment and walkway. The track hoe was then pinned on its side between the 40-foot 2 30-foot 2 3-foot slab of concrete and the hillside. The boom and cab of the track hoe were suspended 30 feet above the ground at the original abutment-grade level. The bottom of the track hoe was four feet off the unstable slope below.
 View of unaffected side of bridge, showing remaining 40 feet of walkway. (Photos by Helen Marie Fitzpatrick unless otherwise noted.) |
The concrete slab sliced through the operator’s cab, immobilizing him between the slab and the cab; his upper body was pinned by the machine’s control levers. The slab of concrete acted as a raker shore in pinning the track hoe against the hillside, which prevented the track hoe from falling away from the hillside. However, it did not eliminate the possibility of the track hoe’s falling straight down, through the concrete slab.
FIRST PRIORITY: TRACK HOE STABILIZATION
A heavy rescue response was dispatched, including the deputy chief of Special Operations for technical support. (NOTE: All Seattle fire operations companies are trained to Operations level in rope, confined space, and heavy rescue as per NFPA 1670.)
When the first Seattle fire unit arrived, the members denied access to the area, identified rescue zones, and prepared the edge protection for the technical rescue team. They reported that the track hoe weighed 105,000 pounds and required a reach of 60 feet for a crane lift, which proved to be vital information when requesting additional resources.
When the technical rescue team was on-site and the incident command system had been established, a reconnaissance of the track hoe situation was initiated. Seattle Fire, after consultation with the private crane crews and the demolition construction crew, determined that the track hoe was stable enough to initiate a rescue.
CONTINGENCY PLANS
The Special Operations chief then developed three contingency plans in case the stability of the scene was compromised. Although none of the plans were used, each plan was based on victim condition, available resources, risk analysis, and timelines.
1. Vertically lift the track hoe to relieve the pressure on the operator’s cab. A vertical lift would have been necessary to get an access opening for the rescue. For this lift, we would have needed a 300-ton crane, which was 60 miles away at the time. We ordered the crane and provided it with a Washington State Patrol escort. This option was the quickest, but it carried the most risk.
Timeline to incident: 2 hours
Timeline to set up crane and lift: 1 hour
Total: 3 hours
2. Utilize a crane to lift and crib in place.
Timeline to incident: 2 hours
Timeline to set up crane and crib: 2 hours
Total: 4 hours
3. Build shoring underneath the track hoe. The void space under the track hoe was a triangular 25-foot 2 20-foot area with a 10-foot-high mound of sloughed dirt. In conjunction with a shoring effort, a crane would be required to stabilize the track hoe while workers shored below. A footprint would have had to have been dug out from under the slab before the shoring could begin. (The concrete slab weighed 500,000 pounds, and the track hoe weighed 105,000 pounds.) Seattle Fire carries 4-inch 2 4-inch timber on its shoring flatbed. The flatbed responded to a lumberyard to procure 8-foot- and 16-foot-long 12-inch 2 12-inch and 6-inch 2 6-inch railroad ties. In addition, spikes and sledgehammers were procured.
Timeline to incident: 1.5 hours
Timeline to build the shores: 3 hours
Total: 4.5 hours
SECOND PRIORITY: STABILIZE THE VICTIM
Seattle Fire medics administered oxygen, established IV lines, and administered morphine and Valium to the victim. He was conscious, was talking to rescuers, had stable vital signs, and was placed in a precautionary cervical collar. Initial triage revealed significant trauma to the pelvic region; the major concern was crush syndrome (which occurs when the pressure is relieved in a crushing injury and the victim experiences a dramatic drop in blood pressure; at the same time, a large amount of lactic acid is released into the circulatory system, causing cardiac irritability and arrest). A white towel under the boom indicated the victim’s location.
THIRD PRIORITY: OPERATING SAFELY
Since it was determined that the track hoe was stable, we began our rescue operations. All firefighters operating from the track hoe worked in harnesses attached to fall protection lines; only five rescue technicians and one fire medic were allowed on the track hoe. Divisions were established on all sides of the incident, and an aerial apparatus was situated on the running trail for an aerial stokes rescue once the victim was extricated. Two medic units were requested to the scene and positioned on the upper abutment side and on the running trail, providing two options for victim evacuation.
 The angle of the slab prevented fire department personnel from working off its face. |
The risk benefit analysis determined that we could work off the track hoe slowly and without applying great force. For victim access, the technicians used a die grinder, a reciprocating saw, rotary hammers, and small hand tools to cut away some of the cab.
Foam lines were positioned on the abutment and on the running trail to protect the victim and rescuers in case of fire.
EXTRICATION
Rescuers made an opening through the cab cutaway and created a small gap in the concrete. They fitted the victim into an LSP halfback (a short board that provides spine immobilization and has vertical lift capability) and then moved him by aerial stokes to the medic unit on the trail. His blood pressure dropped from 120/70 to 70/palp, requiring the medics to use MAST trousers as splints on his legs. He was flown to Harborview Medical Center and diagnosed with severe internal injuries and a fractured pelvis and femur.
(Note: The victim was extricated in 2 hours and 58 minutes from the moment of dispatch.)
LESSONS LEARNED
Sufficient crane size. A 200-ton crane was brought into the area to provide temporary stabilization. After an updated risk analysis, it was concluded that the 200-ton crane was insufficient to support the weight of the track hoe. Note: When ordering a crane, relay the following information to the crane company: the type of equipment you are lifting, the weight, and the reach for the boom to lift vertically.
 Preparing the patient to be vertically extricated. (Photo by © 2002 Marc Carter.) |
The Seattle Fire Department uses the Federal Emergency Manage-ment Agency’s calculations for standard weights of common building materials (i.e., concrete weighs 150 pounds per cubic foot, wood weighs 35 pounds per cubic foot, steel weighs 90 pounds per cubic foot, and so on) to estimate loads. We are also instructed to query the operator of the machine or to look for the specifications plate (usually on the interior of the door).
Communications. All observations and decisions were well communicated on the scene. Recognize the expertise that may be on-site, and use it as appropriate. We consulted the demolition construction crew and the crane crew; they provided good intelligence on the ground stability, specifications on the track hoe, and lift options.
 The arrow shows the void space – a significant challenge to stabilize. Early planning is critical. |
Instead of providing an operator with a radio (our radio protocols and communications may not be entirely understood by civilians), we partnered the construction foreman with a fire department liaison so that information could be passed between the agencies quickly and accurately.
Medical care. The victim was never left without a paramedic evaluating, treating, and calming him.
Patient fluid replacement. The victim received five liters of lactated ringers. Consider an infusion of whole blood in protracted crushing incidents.
Planning. Establish your action plan, but always be thinking of contingency plans. Heavy rescues are very rare but dynamic, so it is sometimes easy to overlook important details.
Additional resources. This incident required two hoselines, equipment haulers, an aerial stokes crew, two medic units, the technical rescue team, and all incident command positions. Request plenty of resources to the incident early; recognize that you may be on-scene for many hours, so plan for your city coverage accordingly.
Shoring resources. Preplan your shoring assets. In Seattle, we have agreements in place with public utilities to mobilize their trench shoring equipment. We also have blanket purchase contracts with city vendors for shoring supplies. In addition, the USAR cache in Seattle can be activated within one hour.
Develop a relationship with your local civilian heavy machinery construction companies so you know who should be called and what information is required. In Seattle, we can call on our USAR structural engineers and the city’s geotechs for assistance. We also have blanket contracts for heavy equipment and agreement with public utilities for equipment.
Media relations. Recognize the importance of a public information officer on-scene dedicated to the media. This type of incident is highly public and time-consuming; the media’s satellite trucks and helicopters were on the scene in minutes.
BRYAN HASTINGS is a battalion chief and a 16-year veteran of the Seattle (WA) Fire Department. He is currently assigned to Battalion 2, which operates out of and has responsibility for the downtown and business district of the City of Seattle. He is also the Plans Section chief for the USAR team and the Metropolitan Medical Strike Team.
A.D. VICKERY is a deputy chief and a 36-year veteran of the Seattle (WA) Fire Department. He currently is assigned to Special Operations. Vickery has served as a firefighter/paramedic, as the head of the Fire Investigation Unit, and on both engine and ladder companies.
