SUBJECT:Winch Operations At Rescue Scenes
TOPIC:"Red Flag" Moments During Winch Operations
OBJECTIVE:Understand conditions and situations during winch operations that indicate unsafe acts and/or diminished safety exists. These are referred to as "Red Flag" moments.
TASK: Based upon study of a real-world cable failure incidents and past experiences, create a list of potential "red flag" moments that can exist at any winch line operation. Develop operational winch guidelines to insure safe and efficient winch line operations at incident scenes.
Sometimes it takes a near miss to get you thinking just how close you came or just how little you know about something that could kill you. Such is the case after a tow truck winch cable failure occurred at a truck crash scene recently. In this situation, the cable failed violently and could have killed two people right before our very eyes. By relating this story to you, it is hoped that the next time you are present at a scene where a winch cable is being used under load, you'll remember this story, set up a safe scene, and avoid a near miss like we had.
The vehicle that crashed was a 10-wheel truck outfitted with a tank to haul waste grease and oils from food establishments. At an on-ramp to an expressway, the driver lost control, rolled the vehicle onto its' roof, and slid to a halt in a ditch at the side of the road. Citizens removed the injured driver just as the first FD units were arriving on scene. There was a small spill of fluids from the truck itself that were quickly contained by fire department personnel. The tank remained intact although it was almost completely dislodged from the truck chassis.
A local wrecker company was summoned by the police to recover the overturned truck. Rather than off-load the tanker, the tow truck operator decided to upright the loaded unit with a low angle, dual line pull off their heavy duty wrecker while fire department personnel stood by. In the process, one tow cable suddenly snapped in two and violently whipped around the scene, narrowly missing two tow truck company employees. The following images tell the story of what happened and the lessons learned.
The challenge to fire and rescue personnel who many times are standing by during these recovery operations, is to analyze these images and identify the telltale "Red Flags" moments that were completely overlooked or not respected by tow company personnel. Once you know where the dangers lie at the scene of a winch line recovery operation, decide what your course of action will be for your fire/rescue personnel.
Photo 1 This is how first-due fire/rescue personnel found the scene upon their arrival. The injured driver was being pulled from the cab through the open door by motorists who had stopped at the crash scene. Note that the chassis of the 10-wheeler appears intact.
Red Flag: The norm for this type of recovery is to pump-off the liquid, called off-loading, to minimize the possibility of a spill of any liquids into the nearby storm drain during vehicle recovery. If nothing is leaking from the tank now, then nothing should be leaking from the tank once it is finally removed from the scene.
Photo 2 A view from the rear shows the waste tank almost completely torn away from the chassis of the truck. The waste oil tank did not leak; only fluids from the truck itself had to be dealt with by fire/rescue personnel.
Red Flag: Note that the tank is resting on a short but relatively steep downhill slope. An uphill pull to recover this fully loaded tank and truck will require greater effort and place more strain on the pulling system.
Photo 3 The heavy duty tow truck operators placed their 16-ton capacity unit at a 90-degree angle to the overturned truck. They hooked one winch line high on the front axle and a second line to the rear tandem axle and began pulling the loaded tanker. This image was taken just as the second winch line was being placed in service.
Red Flag: Note that at this point, because the tow operator has decided to attempt to recover the loaded tank and truck, the resistance of the load being pulled has caused severe twisting of the truck's chassis. This is not good. You don't normally see heavy steel frame rails bend to this extent during a truck recovery done by professional recovery personnel. This is a sign that there is a lot of energy being put into this low angle pull.
Photo 4 The pull is now so extreme that the cab of the truck is actually being lifted off the ground. The resistance of the weight of the waste tank plus the holding strength of the one attachment plate bolted to the chassis is causing a winch overload situation.
Red Flag: This is truly a "Red Flag" moment. Something is about to go wrong! Just consider the potential energy that is stored up in this system. The tow truck operator is literally trying to tear the truck away from the fully loaded tank.
Photo 5 This is the scene from the opposite side just a few seconds before cable failure. The operator of the tow truck is at the rear of the truck. His partner is standing in the foreground with his back to the camera. As the stress of the pull became so great, the front wheels of the tow truck actually rose approximately 18 inches off the ground.
Red Flag: Personnel too close to a working winch cable line is a bad thing. If a cable should fail or a hook or chain length fracture during the stress of a pull, the wire rope cable will whip about violently until it loses its' stored energy. The area that the failed cables can slice through is equal to the distance from the tow truck boom to the crashed truck. A distance greater than this in all directions should be kept clear of all personnel during the pull, no exceptions. Tell the operator, "I don't care if that is your tow truck. You're going to be killed if that winch line fails. I'm the Fire Department Safety Officer at this scene and I won't allow you to stand there!" Anytime anyone is within the 'strike zone', they are in great danger.
Anytime the front wheels of a heavy duty tow truck come off the ground, something is probably wrong as it was in this case. At that moment, the cable closest to the camera violently failed. The failure occurred about four feet beyond the pulley block at the top of the tow truck boom. The 35 feet of broken wire cable shot like a bullet towards the overturned truck, slamming into the undercarriage.
This failure location actually saved lives. If the cable had failed closer to the damaged truck or if the hooks or chain had fractured, the cable would have whipped backwards towards tow truck itself. The tow truck operator and his partner were both within the strike zone of the cable had the failure occurred at this location in the line.
Photo 6 A closer look at the end of the tow cable shows the tremendous, almost explosive result of sudden cable failure. The stored energy built up within the cable is instantaneously released. It is that release of energy that creates the winch line "flying cable" potential.
Photo 7 The line failed several feet from the tow truck boom. Because of that failure point, the free end of the cable traveled away from where the two tow truck personnel were standing. Had the failure been at a different location, the results would have been fatal.
The challenge is to develop guidelines describing what we could do at a future incident anytime a winch cable is being used at an incident scene.
TASK: Based upon study of a real-world cable failure incidents and past experiences, create a list of potential "red flag" moments that can exist at any winch line operation. Develop operational winch guidelines to insure safe and efficient winch line operations at incident scenes.
