BY RON SHAW
Changes in new vehicle construction, alternative-fueled propulsion, and occupant-safety systems are only some of the topics that should be addressed in today’s protocols for responding to motor vehicle crashes. The introduction of hidden roof-mounted (IC) air bags and pressurized gas inflators in the areas we routinely use as cutting zones for displacing and removing the roof are other innovations that also should be covered in standard operating procedures (SOPs) or standard operating guidelines (SOGs).
When updating your extrication policies, keep in mind the following:
- Extrication policies. They should allow some flexibility that will enable the on-scene incident commander or extrication sector leader to adapt the procedures according to the circumstances at hand.
- Vehicle rescue policies. They should be as generic as possible so that they can be applied to incidents involving conventional and innovative vehicles, including the hybrids and fuel cells of the future. Standards topics should include, but not be limited to, those discussed in this article.
- Scanning the scene. This technique, originally developed by Ron Moore, Plano, Texas, involves the responder’s visually searching for hazards such as telltale signs of supplement restraint system (SRS) components. Extrication.Com expanded the scanning technique to include hazard awareness for the entire rescue area and vehicles, not just the interior of the crash vehicle. Scanning the vehicle should be a visual, ongoing process that involves checking for all types of hazards, including SRS, electrical, biohazards, spills, and the physical instability of the vehicle. The interior scanning of air bags includes looking for nondeployed frontal air bags; “seat belt” air bags; pretension; and the not-so-obvious hidden side-impact protection (SIP) in seats, doors, pillars, and roof rails. Visually identifying SRS hazards enables the responder to weigh the options and adjust tactics according to the active SRS hazards present. Additionally, the responder may elect to pry back before cutting or displacing metal near SRS components, to ensure a safe zone within which to work.
- Immobilize the vehicle. Prior to the millennium, we could assume that a silent crash vehicle was stalled or its ignition was turned off and the vehicle was not operational. You cannot make those assump- tions concerning innovative vehicles with electrical propulsion such as hybrids or fuel cells. Although they may be silent, they can start up and take off instantly while in gear. Unlike vehicles with conventional propulsion, an electric system does not require a starter motor to crank/turn over the gas engine. The electric drive motor doubles as a starter for the internal combustion engine. For this reason, it is important that all vehicles be immobilized to prevent them from moving by gravity or under power. Immobilizing the vehicle is as simple as placing a wheel chock or another suitable blocking device to the front and rear wheel.
- Disable the vehicle. Shift the vehicle into park, and shut off the ignition/power. This will shut down the ignition system, the fuel pump, and the battery power to most SRS. Doing this causes the SRS reserve electrical charge in the capacitor of the electric control unit (ECU) to drain down.
- Disconnect the power [12-volt (v) battery] as soon as possible to prevent the SRS from accidentally deploying during extrication. When necessary, disconnect the low-voltage battery supply. However, in a hybrid vehicle, disconnecting the 12-v auxiliary battery may not safely power down the low-voltage system. In some hybrid systems, the high-voltage system can be stepped down (via converter) to provide power to the low-voltage system if the vehicle is “on.” Vehicle propulsion is still capable in this situation, even if the 12-v auxiliary battery is disconnected. For this reason, it should be department policy for responders to immobilize all vehicles at a crash or fire. It is not necessary to disconnect the power at every incident—for example, a minor motor vehicle crash not requiring extrication may not indicate that the battery power needs to be shut down. As a general rule, if extrication is indicated, then power down the vehicle as required and according to your department policy or as recommended by the manufacturer for that make and model. Never try to disconnect or cut any high-voltage power cables or components; serious electrical burns or electrocution may result! Department policies should be based on current manufactu
It is important to turn the ignition key or push the power button to the “off” position. Doing this will provide increased safety at a hybrid vehicle crash by accomplishing the following:
(1) Modified Dash Roll (MDR), the latest method for displacing dashboards safely. (Photos courtesy of Extrication.Com unless otherwise noted.)
(2) Hidden behind the roof rail are the hybrid inflator and the IC air bag.
—prevents the vehicle from moving under its own power;
—opens (disrupts current flow) low-voltage relays, shutting down the HV system;
—isolates the high-voltage battery power; and
—shuts down the fuel pump.
Hybrid systems have inverters that step up HV battery current (144 v to 300 v) to a higher voltage and can store this high voltage (up to 500 v) current even after the HV battery power is shut down or disabled. Never assume that the HV electrical system is safe by simply performing power disconnect. Refer to the individual make and model ERG for inverter capacitor power drain-down times and other responder safety recommendations.
Note: Before disconnecting the 12-v power, actuate the vehicle’s motorized components—electric power locks, latches, windows, and seats. Killing the power to an electric seat that must be moved for operations can add critical minutes to the overall rescue efforts.
- Properly stabilize crash vehicles. Step blocks or cribbing can be used to transfer the vehicle’s weight from the wheels onto the cribbing. Vehicles in unusual positions may require specialized stabilization equipment such as tensioning mechanical struts.
Additionally, address the rescue techniques appropriate for cutting, crushing, pushing, or spreading metal components in vehicles with deployed or nondeployed SRS components. The risk of accidentally deploying the SRS is greatest during this phase of the rescue. Without an SOP or an SOG, there is a greater chance for freelancing, increasing the potential for the SRS’s accidentally being deployed or a hidden pressurized gas inflator’s being breached.
SRS SAFETY: TIME AND DISTANCING
The ECU capacitor can store an electrical charge from zero to 10 minutes or more, depending on the vehicle’s make, model, and year. Older SRS typically have the greatest reserve capacitor drain downtime. Keep in mind that not all air bags are activated by electrical current: Some side-impact protection systems and older frontal driver air bags are activated by mechanical initiators. The responder cannot reliably deactivate the mechanical SRS in the field.
Safety Note: If air bags are nondeployed, do not cut into, crush, intentionally deploy, or restrain an air bag or its components; serious injury may result. Should there be a situation where no other options are available and a side-impact curtain or similar side-impact air bag must be cut, consider the active inflator side a hot zone. As an example, it is impossible to displace a dash when the side-impact curtain air bag inflator is located in the A-pillar or the windshield pillar. In this situation, the curtain air bag will need to be cut to rotate the dash up and away from the victim.
(3) SRS controller/ECU capacitor.
(4) Hidden hazards: Look before you cut.
Always distance yourself from a non-deployed air bag. Potentially, any non-deployed supplemental restraint device has the capability of activating, even when the vehicle’s power is disconnected. As a redundancy, practice distancing yourself as much as possible from the air bag deployment path. The “5-10-20 Rule for Air Bags” below can be used as a guide. And, do not place any hard object in the deployment path. Serious injury could result if the air bag is accidentally deployed.
- 5 inches for side-impact air bags. Determine what type SIP is present and its potential deployment path. Distance yourself 5 inches alongside and parallel with the door and deployment path of the air bag.
- 10 inches for driver frontal air bags. Driver frontal air bags typically deploy outward from the steering wheel hub to the vehicle operator for a distance of approximately 10 inches.
- 20 inches for passenger frontal air bags. The passenger frontal air bag will deploy outward to the frontal passenger(s) for a distance of 20 inches or greater.
5-10-20 RULE FOR AIR BAGS
Not all air bags are included in the 5-10-20 rule. The rule is a generic guide for the most commonly found air bags. Newly developed air bags, such as knee bolster and carpet (floor-mounted) air bags that may be present in new model vehicles, are not included in the rule.
Don’t be fooled by the size of a side-protection air bag. Even small SIP air bags will deploy incredibly fast with considerable force. An SIP air bag’s deployment path will be within the occupant cage and is intended to block the occupant from side-impact intrusion. The 5-inch rule corresponds in direct relation to the centerline of the air bag’s deployment path as it deploys up/down along the window area or out from seat-mounted air bags. It does not refer to the actual deployment path in front of the air bag, as the 5-10-20 Rule does for driver and passenger frontal distancing.
Many air bags deploy down from the roof, up from the door, or forward from the seat. Scanning the vehicle for telltale air bag identifications will indicate which type of SIP is present and the actual deployment path.
(5) IC icon, windshield pillar.
(6) IC icon, B-pillar.
DISPLACING AND REMOVING THE ROOF
For decades, responders have been taught that displacing (flapping) and removing a roof create an open space for greater victim access, care, packaging, and subsequent removal. Although this is true, this principle was conceived prior to the introduction of the side-impact curtain and pressurized gas inflators in the late ’90s. Following are alternative methods for safely mitigating a rescue with active SIP. However, you still must know how to properly displace and remove the roofs of vehicles without active roof-mounted air bags, so do not discard the older philosophy yet.
Since no two crashes are identical, the on-scene extrication sector needs to be adaptive and remain flexible. External factors may dictate how the rescue must be mitigated. That is why, as stated above, written department policies covering incidents involving vehicles with deployed and non-deployed air bags should be in the form of an SOG. This is especially true when roof displacement or removal is required.
Some General Guidelines and Precautions
The on-scene incident commander or extrication sector leader determines if it is necessary to displace or remove the roof. When it appears necessary to do so (it is the only way to remove a victim, for example), a risk vs. benefit analysis/assessment must first be done. The incident commander also should consult with EMS and the extrication sector to decide if displacing/removing the roof is necessary and, if so, how to do it in the most safe manner. The commander/rescuers should be knowledgeable in vehicle construction, air bag systems, nondeployed SRS hazards, and the options/alternatives available for safely accomplishing the rescue.
Some guidelines and precautions for displacing or removing the roof follow:
- Pull back the interior trim to locate and avoid the SRS wiring harness and IC and inflator(s).
- Do not allow any body parts within the deployment path of the IC or other air bags.
- Do not cut into the inflator.
- Avoid cutting into the air bag (cushion).
- Disconnect the battery as soon as possible and before cutting or displacing metal.
- Do not place a hard object between a nondeployed air bag and a person.
- Do not attempt to disable the inflator; you could inadvertently activate the SRS.
- When displacing a roof, do not hold along the deployment path of a non-deployed impact curtain; it could accidentally deploy.
- Store all vehicle parts with active air bags pointing up, and do not allow any other objects to be placed on top. These items should have a separate debris pile, and security barrier tape should be used as a warning device.
- Two personnel should always be informed about active air bags and their locations (in the debris pile, for example).
SRS Safety Precautions
Do not cut through an undeployed curtain or the inflator. If the side-impact curtain is activated, hot/cool pressurized gases will be generated and forced out through the cut open butt end of the air bag (curtain). Released gases can be forcefully liberated directly at the responder or victim. In instances when you cannot avoid cutting into an active impact curtain (air bag), consider the cut section as a hot zone, because of the potential for accidental deployment. Once the IC has deployed, it will retain its inflated state for up to 10 minutes. Should it be necessary to cut through a deployed impact curtain, doing so with heavy rescue tools should not present a safety issue.
However, if the IC system was activated, hot/cool pressurized gases will blast out from the inflator through the now unrestrained open butt end created from cutting the air bag. Normally, the deployed impact curtain, unlike frontal air bags, would retain these gases for a period of time because of the possibility of a rollover. As in the case of a frontal SRS, the hot gases will not burn the occupant while they are contained within the air bag-IC.
Avoid breaching active SRS components. One of the simplest ways to reduce the risk of injury is to avoid cutting into locations that contain SRS components. In addition to knowing the different components and systems, you should be able to identify the locations of SRS components by the telltale SRS icons (examples include SRS, SIP, SIPS Air Bags, and IC) or by prying back interior trim in the area where you intend to cut into pillars or roof rails.
Safety Tip: Do not cut blindly into vehicle pillars or roof rails. Doing so increases the risk of injury. Look before you cut! If there are active impact curtains, seek alternatives for displacing or removing the roof.
When it is necessary to displace or remove active side-impact curtains or the roof, you should ask, “What are the risks vs. the benefits, and what are my options?” Do not compromise victim care, particularly when the extrication sector has alternatives.
Scan for IC identifiers. Scan the interior of the vehicle for IC identifiers. If necessary, pry back the interior trim to locate the SRS component or to verify that the cut zone is clear of SRS components.
When you encounter resistance consistent with that of a hard metal object when cutting into a pillar or roof rail, STOP cutting and look to see if an IC inflator is present. Visually scan the interior of a vehicle, taking in everything and interpreting what you find, and then act accordingly.
Most automobile manufacturers have adopted the icon (letters) “IC” to identify a hidden side-impact curtain. This identifier is generally at the outer edge of the interior roof liner trim. Commonly, when the IC is full length (rear pillar to A-pillar), you will find an interior trim end cap with an embossed “IC” above the rear pillar. The interior trim end cap snaps over the joint union between the roof rail trim and the rear pillar trim. If undeployed, do not cut into the roof rail or rear pillars.
Do not position body parts in the deployment path while displacing or cutting metal near the system’s components; serious injury could result should the SRS accidentally deploy.
Automobiles are commonly equipped with both IC and door- or seat-mounted SIP. A side impact to the rear quadrant can deploy the IC to protect the rear occupants. However, the frontal SIP (front door or seat-mounted air bags) may or may not deploy, depending on the activation parameters set by the engineers for that make and model vehicle. Conversely, an impact close to the driver or front passenger will deploy both frontal SIP and IC for that side of the vehicle. In the case of the Audi in photo 9, the driver’s seat-mounted air bag and the IC deployed together. Seeing a deployed IC does not necessarily indicate that all SIP air bags have been deployed on that side of the vehicle.
Safety Tip: Do not cut blindly into a structural component without first knowing what is hidden behind it. Doing so could cause the cutting tool to side load or fracture, or possibly breach a hidden inflator’s pressure vessel and create a projectile. Another problem with cutting along the outer roof rail of a vehicle with a non-deployed IC is that activating the inflator and cutting the curtain creates an open butt from which hot pressurized gases can be released without restraint and injure the victim or responders.
(7) IC icon, rear pillar.
(8) Door-mounted SIPS used in conjunction with IC.
(9) Audi A-4 with seat-mounted SIP used in conjunction with IC. [Photo by Lt. Terry Salvi, City of Bedford (OH) Fire Department.]
ALTERNATIVE TECHNIQUES FOR COPING WITH SIDE-IMPACT CURTAINS
Following are some alternatives to removing vehicle roofs.
- Roof displacement: halo cut. You can open the roof to remove victims by cutting out a section of the roof without removing all the roof’s structural members (see Figure 1). This is referred to as a “halo cut” (an open ring in the roof).
- Roof displacement: side flap. A side impact would normally cause only the side air bag(s) on the crash side of the vehicle to deploy. The side-impact air bags on the other side will remain active, hampering roof removal or displacement. You could use a side flap to safely displace the roof back to and over the undeployed side of the vehicle. Once the roof has been displaced, you have the option of securing it in place or cutting and removing the flap.
- Dash displacement: modified dash roll (MDR). For decades, removing a roof or flapping was done in conjunction with dash displacement—you can’t roll a dash with the roof on, right? Wrong! Since the introduction of side-impact curtains, the concern has been that responders will cut into the hybrid inflators. During bench tests, whenever the pressure vessel was breached by a heavy rescue cutting tool, projectiles resulted.
You can rapidly displace (roll or jack-vertical lift) an automobile dash without flapping or removing the roof. This technique, developed by Extrication.Com in the late ’90s, is referred to as the “modified dash roll” (MDR). The MDR has been accepted by civilian and military agencies worldwide over the past three years and can be used in the following situations:
- To avoid SRS when located aft of the A-pillar.
- For rapid intervention, four to six minutes or less.
- In vehicle under/over rides.
The MDR doesn’t give the EMS sector a large open area to the occupant cabin, but it avoids the hazards posed by a nondeployed IC or the breaching of the gas inflator. The MDR should be thought of as another tool in the box. It was not designed to replace any particular technique but to enhance rescue efforts and reduce the potential for an injury from side-impact protection systems.
In the May issue, I addressed common hybrid inflator locations. Since the article was submitted for publication, Mercedes introduced a new hybrid inflator location at the bottom of the windshield pillar just above the dash. In this situation, the only possible recourse for the responder will be to cut through the curtain air bag just above the hybrid inflator to displace the dash. This goes against all recommendations of cutting a nondeployed air bag. However, there is no other way to safely displace the dash. Once the cut that severs the windshield pillar and the hidden curtain air bag is made, consider the section of the pillar with the active inflator to be an SRS hot zone, as previously mentioned. As the dash is rotated up and away from the victim, the gas inflator deployment path should be elevated up away from the victim and responders.
Emergency responders should continually be seeking from the automotive industry the latest information concerning vehicle safety features and the potential hazards that are posed in a motor vehicle rescue. This will allow program developers, training officers, and instructors to evaluate the effectiveness of their current training curriculum and to explore alternative procedures for meeting the most current demands at a crash in the safest way possible.
The industry will constantly be developing new air bags for increased occupant safety. Responders will have to adjust their training and department policies to ensure their safety and meet the demands created by new safety innovations and vehicles.
RON SHAW is a lieutenant in the Plymouth (MA) Fire Department. He is the founder of Extrication.Com, which provides motor vehicle rescue/extrication training and online safety information. Shaw is currently compiling the Extrication.Com Vehicle Extrication: Basic Skills textbook for Jones and Bartlett Publishers.