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SAFETY CONSIDERATIONS IN THE DESIGN
OR PURCHASE OF ENG VEHICLES
By Henry Lassige, Sr.
In recent years, there has been a rash of accidents involving ENG crews, and the focus is now on
ENG safety. To date, industry response has been information about safety equipment and safe operation of ENG units. This paper takes a different approach by discussing safety from the ground up - from
OEM options and after-market modifications to safety features you should consider when building an ENG unit in-house.
First Things First
With safety as our benchmark, the first task is to define the vehicle’s purpose in order to
determine its chassis style. Will it be an ENG, DSNG, SNG or combo unit? For the sake of simplicity, we will consider an ENG or DSNG unit so that we can limit our scope to cargo vans.
A one-ton cargo van has a GVW of 9,400 lbs. With proper equipment choices, either an ENG or
DSNG unit can be built with a delivered weight of 8,500 to 9,000 lbs. GVW. Adding personnel, fuel and support equipment brings the unit very close to the maximum GVW. As a result it’s
extremely difficult, if not impossible, to build a combination ENG/DSNG unit and stay within the allowable GVW.
The response to this problem usually ranges from “So what if the unit is a little over weight?
That just means it will burn a little more fuel,” to “We don’t have the budget to build two dedicated units. Besides a combo unit is more efficient.” While these points are well
taken, there are other factors to consider. Added weight means not only higher fuel consumption but also faster tire and brake wear. Far more importantly, however, added weight compromises overall
vehicle safety. Brake size will be inadequate and the stopping distance will increase. Greater roof mass will change the center of gravity, increasing the chances of tire blow-out and loss of
control. And finally, if an accident does occur, an over weight vehicle will make you liable even if you were not at fault. So while tempting, a combination vehicle at the one-ton cargo van
weight will put your personnel, the general public - and your bottom line - at risk.
Basic Chassis Design
There are two chassis choices: uni-body and full frame. With uni-body construction, the integrity of the
chassis depends on the one-piece body construction. Any modification to the body, such as that required for ENG van conversion, weakens the overall strength of the unit. On the other hand, with
full frame construction, the body is bolted to and supported by two steel u –channels that run the full length of the chassis. Any holes that are put into the body do not have the same adverse effect
as with uni-body construction. Therefore, full frame construction is more robust and readily lends itself to ENG type body modification.
Style Matters
There are two body styles to consider: the standard 114” wheelbase or the 138” super cargo van. The
standard wheelbase offers a tighter turning radius and easier parking. However, while longer and more difficult to park, the super cargo van has the advantage of an extra two feet of space, a big
plus when a crew is covering a story for an extended period of time. As a result, our choice - as with most ENG units today - is the 138” super cargo van body style.
Factory Options
Now we turn to important options, beginning with the engine. The large block engine is a good choice for the
unit’s power plant. The more power the engine has, the less it has to work. A large block engine also has the reserve power that may be needed in an emergency.
Given the weight these units carry, four-wheel, anti-lock brakes are a good option, particularly for
controlled steering during a panic stop. To effectively and safely use anti-lock brakes, however, operators should be required to read the manufacturer’s manual and familiarize themselves with the
proper application of these brakes.
As for gear ratios, a low gear ratio (4:10 or 4:11) is preferred. It requires less engine torque to move the
vehicle and, in combination with engine back-pressure, aids in stopping the vehicle. A limited slip version is also well worth considering because it enables either rear wheel to drive the unit in snow
or mud.
Handling is also a safety consideration, and we suggest ordering the highest rated factory suspension.
Typically, this type of suspension provides increased spring load capability, heavy-duty shock absorbers and a front sway bar.
So now we have a one-ton ENG or DSNG super cargo van with full frame construction, large-block engine,
four-wheel anti-lock brakes, a low gear ratio and a top-of-the-line factory suspension. We also suggest adding a cargo door window, which offers increased side visibility for added safety; for security,
after-market intrusion bars can be added.
Powerful Safety Considerations
Believe it or not, factory-installed power locks, windows, seats and mirrors are safety items. Power locks and
windows are invaluable in unfamiliar or dangerous areas. And if operators must manually readjust seats and mirrors each time they get into the unit, chances are they won’t take the time to do it -
setting the stage for sub-optimal visibility and operator control.
Dual air bags are a significant safety feature, and they should be ordered on all vehicles. The
availability of dual air bags has resulted in the introduction of new government regulations, which are covered in the Code of Federal Regulations - 49CFR FMVSS 517.207 through 517.210. Of
particular interest is the fact that since 49CFR went into effect, OEMs have dropped swivel seats from the OEM option book, and van conversion companies, RV manufacturers and companies that manufacture
seats and seat bases no longer offer front swivel seats for use in units rated under 10,000 lbs. GVW.
Any ENG unit rated under 10,000 lbs. GVW with a front swivel seat must comply with FMVSS 517.207 and 517.210
and include documentation confirming compliance in the documentation package. Producing a compliant seat base must adhere to the installation process detailed in FMVSS 517.208 (occupant crash protection)
and 517.209 (seat belt construction).
Compliant swivel seat bases are available for use in the operations area however, if it is to be used for the
transportation of personal it must be locked in the forward facing position. All hardware used to attaché the base and seat must be grade 5 case hardened steel.
Regarding seat belts, the major supplier of chassis for ENG conversion includes a front seat belt system
with a pyrotech device that fires upon impact, pulling the occupant back into the seat. Any changes made to the front seats must not adversely impact this system.
After-MarketENG Modifications
Let’s now return to the purpose of the vehicle. An ENG or DSNG unit will be operated at or near
its rated GVW over its lifetime. Because the factory does not calculate 24/7/365 operation at the maximum GVW into the basic design, a prime consideration is suspension payload capacity, which
should be increased by 50 percent. This does not mean that the unit can be overloaded; instead, it means that as the original equipment fatigues with age, the after-market suspension system will add
longevity to the suspension and provide sufficient head room for long-term safe handling.
As noted earlier, heavy-duty factory suspensions are generally configured with a front anti-sway bar. A
heavy-duty rear anti-sway bar also should be added to help counteract the forces of gravity as the unit corners. This is especially true for ENG units in which the center of gravity is higher than
that of automobiles or unloaded vans.
Another consideration for ENG vehicles is an overdrive inverter. Currently, manufacturers incorporate an
overdrive mode into vehicle design in order to meet mileage standards that are mandated by the government. Although overdrive does increase highway mileage, it also increases stopping distance and
hastens wear on the brakes and transmission. A solution is an overdrive inverter, which causes the unit to come up in third gear; deceleration occurs the second the accelerator is released and this
action, combined with engine back-pressure, decreases the stopping distance. The overdrive inverter is especially useful in heavy congestion - and has the added bonus of increasing brake and
transmission life. If overdrive operation is desired, the driver can simply activate the overdrive button.
Building In Strength
Because equipment, racks and the body itself will be subject to the rigors of road travel, reinforcement is
key when preparing the body of an ENG unit. Strengthening the overall body means reinforcing the walls with a minimum of 18 gauge U-channel that is welded to the floor and roof. Cross supports should be
welded between the vertical U-channels. The rack base should be constructed using at least the same gauge U-channel and then welded to the van floor and wheel wells. The racks can then be bolted or
welded to the rack base and vertical U channels. Grade 5 case-hardened steel bolts and nuts should be usedas the fasteners.
When allotting space within the unit, care should be taken to distribute the load as evenly as
possible. If the generator and/or air compressor are on one side of the unit, for example, then the auxiliary batteries, cable reels and heavier electronic equipment should be on the other side.
Adding a Deck
If a roof deck is in the design, it should be constructed of aluminum deck plate that provides traction
without snagging shoes or clothing. The supports fixing the deck to the roof should be bolted through the roof and the roof supports. Hardware attaching the aluminum deck to the steel roof must be stainless steel or insulated in order to separate the two dissimilar metals.
A roof edge warning system or railing is absolutely essential if the roof deck will be used for production
activities. A railing can be permanently fixed on the deck or carried on the unit and deployed as needed. In either case, it must be at least 42 inches high. A heavy-duty ladder with a heavy-duty grab
rail must be included to assist in roof egress and exit.
The roof itself should be reinforced around the mast and air conditioner with a minimum of 1/8”
plate. Additional roof cross supports should be welded near any area where a large hole has been cut, such as for a roof view port. A port will enable the operator to visually track the microwave
antenna if fine-tuning of the microwave signal from inside the unit becomes necessary.
Placing and Controlling the Mast
The mast can be installed either in the front or rear of the cargo area. A mast “well” constructed of at
least ¼” steel is strongly suggested in order to keep the mast from kicking out should it strike an overhead obstruction while the unit is moving. This well also will allow for a lower vehicle profile
and thus lower van height. While a good addition to either configuration, a well is a must for a mast installed in the front section of the cargo area.
A cardinal rule is to never raise the mast from inside the unit. Instead, amast deployment control system that
allows control from a distance away from the van should be incorporated. By remotely controlling the mast, the operator can get a better view of the surroundings and, in particular, see what is above the
mast.
The mast and microwave antenna should be interlocked to the vehicle’s transmission. The interlock
should disable the engine if the vehicle is placed in gear when either the mast or antenna is in an un-stowed state. The interlock should never interfere with vehicle operation while driving;
instead, visual and aural indicators should warn the driver that a un-stow has occurred while the vehicle is moving.
A system that automatically stows the antenna and mast is preferable because it allows the operator to focus
on what he or she is doing while breaking down after the shot. However, to preclude potential problems (i.e., loose parts or a mast that sticks), operators should track the mast and associated
equipment during the nesting process.
If an air reservoir is used in the air system, the potential of accidental release of the stored energy must
be addressed. This canbe accomplished in several ways. One method is to add an arming switch that activates the mast up control device. A second is to automatically dump the air from the
reservoir if primary power is absent. Also, the air system should inject lubricant into the mast and include an air drier to eliminate condensation prior to lubrication.
The mast itself should be coated with a material that aids in smooth deployment and nesting. These coatings
are especially useful in cold climates where the mast is exposed to snow, ice and freezing rain. Coated masts utilize heavier-duty seals and O rings than non-coated masts, adding the benefit of
increased mast life.
Power Points
While some ENG units are designed to operate on 12 volts, most operate on 120-volt power. There are four
primary sources of electrical power: shore, generator, inverter and battery.
Shore power enables a unit to run on electricity supplied by the local utility, usually via an extension
cable. This cable should be at least a twelve-gauge, three-wire cable with a heavy rubber outer sheath and marine-type connectors.
Generator power is supplied via an onboard 4-6 kilowatt generator that runs all circuits in the van. Modern
electronic equipment does not require the kind of power needed only a few years ago, so generators typically run under a light load most of the time. Because light load conditions can eventually cause
problems with the generator engine, the generator should be run periodically at full load.
Inverter power is an onboard system that converts 12-volt DC to 120-volt AC. An inverter rating of at
least 1800 watts should be used. Additional batteries are required in order to provide the necessary power. To keep these batteries charged, a high speed idle must be added to the engine, along with
a switch to manually activate and deactivate the idle. Inverters are normally used to power a limited number of circuits or as a source of emergency backup.
Battery power can be the sole source of power, but with limited capabilities.
Compartments
A sealed compartment for housing the generator and the air system is important to personnel safety. It will
prevent carbon monoxide leaks - as well as gasoline, engine oil and mast lubricant spills - in the operations area.
Auxiliary batteries also must be housed in a separate compartment. Standard lead acid batteries require
substantial ventilation and should be mounted and locked in an upright position. Glass-sealed batteries have less stringent ventilation requirements and can be mounted in any position.
As with equipment, the electricalload needs to be distributed as evenly as possible, with the mission-critical
circuits isolated from those that are not. The main vehicle battery needs to be isolated from all other batteries during a discharge condition. However all batteries need to be connected in
parallel with appropriate charge monitoring during the charge mode.
Wiring and Control
All wires must be the proper size for the rated current and should have an SJ or THNN oil resistant
rating. Wiring should run through conduit that is properly terminated. Split Loom or some other type of protective covering should be used in areas where conduit is not appropriate. The
wiring should be marked for easy identification, and proper service loops provided.
A means of controlling and monitoring all the circuits is important. While either analog or digital displays
of voltage, current and frequency can be used, digital monitoring is generally easier to read and interpret. The panel also should include a breaker or fuse for each circuit in the van, with indicators
that alert the operator of circuit function and status. If fuses are used in the engine compartment, they should be heat and vibration resistant.
Lighting and Warning Devices
Marine grade mast up-lights at the top and on the base of the mast are ideal for illuminating the area above
the mast. A mast beacon also should be installed. The beacon serves two purposes: its strobe effect may illuminate an overhead object more readily than a steady beam, and it will aid
helicopter pilots in pinpointing mast locations as they land their craft.
Other safety lighting options include:
- A spotlight or handheld high intensity flashlight for finding street numbers and signs as well as locating overhead wires and
obstructions, utility poles and power lines.
- Warning strobes and beacons to indicate to approaching traffic that the unit is parked.
- DC work lights strategically placed to aid the crew in “set up” and “tear down” and to alert passing drivers of their
presence.
- A work light placed above the ladder to illuminate the ladders rungs.
- Lighting in the operations area so operators can see inside the unit before entering.
Suggested warning devices include:
- Detectors that automatically lower the mast if they sense an overhead obstruction or power line.
- Mast deployment enunciators that remind the operator of the dangers of improperly raising the mast.
- Backup alarms that engage when the unit moves backward.
Also available are CO detectors that alarm in the presence of carbon monoxide; however, some CO
detectors are triggered by strong RF fields, so it’s important to carefully select the proper detector.
Helpful Hints
- Prominently display signs indicating the vehicle’s height restrictions and warning of overhead obstructions and power lines.
- Install multi-use fire extinguishers in both the front operation and rear storage areas.
- Ensure that radios, cell phones and scanners are easily accessible from the driver’s seat. The driver also should have easy
access to the controls for warning beacons and strobes.
- Install GFI receptacles.
- Add a compass to the driver compartment.
- Provide the driver with a monitor that indicates generator hours, vehicle engine hours and battery status.
- Consider adding hood vents to help prevent engine overheating during periods of prolonged idling.
- Make sure each vehicle carries maintenance manuals as well operator manuals, and provide all operators with a copy of the operator
manual. Each manual should cover the safe operation of the unit and include a testing section. Provide training to the end user at the time of delivery.
- Use reflective tape on the exterior of the unit.
- Provide reflective vests for your crews.
Safety Comes Down to You
Manufacturers can install every conceivable safety device and feature, and ENG unit design can reflect a
commitment to the safety of your crews. But there is no substitute for regular vehicle, generator, air system, and electrical system maintenance and for on-going safety training and testing. The
end user must ensure that operators are well-trained in safety practices, that a safety protocol and a hierarchy of command are in place in the event of an emergency, and that the safety program meets
local and federal laws regarding clearance, safety and training.
Henry Lassige, Sr. is president of Alpha Video and Electronics Company (AVEC),
which has provided systems integration, equipment maintenance,
mobile units and equipment solutions to the broadcast market since 1972.
AVEC’s first ENG unit, constructed in 1983 is still in daily service
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