Acceleration is something that many AutoSpeed readers hope to enhance. From turning up the boost pressure, to fitting a monster intercooler and bolting on that free-flowing muffler - we want to feel major accelerative G-forces. But there's one kind of acceleration that occurs in a vehicle that isn't so wonderful - that is, when an unsecured piece of cargo comes hurtling at your body in the event of an accident.
It's likely that we automotive tinkerers are a high-risk bunch of people when it comes to potential injuries - or death - caused by unsecured cargo. Whether you've got a heap of tools floating around on the back seat or you haven't quite got that subwoofer encloser fully tied down, you're putting everyone that rides in your vehicle at risk.
Some of the Dangers
Bear in mind a sobering fact that Adelaide's Milford Industries (Australia's largest manufacturer of cargo barriers) makes in many of its brochures - the rapid deceleration that occurs in a 48 km/h frontal crash increases the effective mass of all loose objects by 20 times. That means a stray 15kg toolbox has a collision mass of 300kg and the average 20kg subwoofer box strikes with a massive 400kg. So you've got a 60kg engine block sitting 'temporarily' in the cargo area of your hatchback? This has a collision mass of some 1200kg!
Note that it is not only heavy-impact accidents that cause cargo to become potentially lethal projectiles - even a heavy-braking manoeuvre (without a collision) can rapidly accelerate unsecured cargo. The steep angles experienced during extreme 4WDing are also capable of dislodging any loosely 'chucked-in' cargo.
Securing a vehicle's cargo is certainly an issue worthy of major consideration.
Milford design, test and construct cargo barriers for just about every hatch, wagon, 4WD and van on the Australian market. Their most common variety of barriers is built using a mild steel square-section tube frame and a mild steel mesh; both the frame and mesh are copper coated (to avoid corrosion) and then powder coated (to give an attractive finish and add further corrosion protection). Selected versions of the steel mesh barriers have a walk-through sliding door option which allows easy through-access into the rear cargo area.
In addition to the traditional steel mesh barrier, Milford also produces a steel framed shatterproof polycarbonate barrier - this is known as the Interceptor. The biggest advantage of the GE Plastics Lexan Exell D Sheet polycarbonate screen is that it's completely transparent (meaning there is no negative affect on rearward vision) and, by functioning as a solid wall, the performance of your climate control systems is also enhanced. The third cargo barrier design Milford has is a 'hybrid' that combines a section of steel mesh with a section of polycarbonate - this product is labelled the Access.
Lastly, the Load Guard is Milford's specially designed cargo barrier for hatchbacks. This unobtrusive safety device comprises a steel mesh guard that fits up against the rear backrest and a shock-cord net that stretches across the top of all cargo. Tricky.
Each of these barriers can be easily installed and removed without using tools thanks to the so-called Milbolt or - where appropriate - they have a quick-release system. Most Milford barriers also fit in two positions - between the rear seat and the cargo area, or immediately behind the front seats when the rear seats have been folded forward for maximum cargo space. All Milford barriers have provisions to allow the upper anchorage strap of a child restraint seat to be secured in the factory position.
Barrier Testing
As mentioned, Milford tests their cargo barriers in-house. This - as you might expect - involves some pretty spectacular testing procedures; one of the most-used is the so-called drop test (which is conducted inside Milford's National Australian Testing Authority approved facility). The drop test sees a cargo barrier mounted on its back just above ground level, and an 110kg mass dropped onto it from a height of around 4 metres. Once the drop is completed, the strength of the barrier is fully assessed - the main pass/fail criterion is the amount of maximum barrier deflection. AS/NZS 4034 standard accreditation states a maximum permissible barrier deflection of 300mm.
The second test that Milford may conduct is the sled test - however, this is usually only performed upon request of car manufacturers, due to the immense cost. This examination sees a vehicle carrying various masses of cargo pulled into a 75-tonne concrete block at 45 km/h (which is the standard crash test level used by car manufacturers). This test is said to deliver a deceleration force of 20g. After collision, the installed barrier is again measured for 300mm maximum deflection and any other potential faults are also noted.
According to Milford's literature, the single heavy mass objects onboard the sled test vehicle - and, of course, those in your vehicle - have the potential to do a lot more damage than an assortment of lighter weight items. Here are some of Milford's test findings:
| Test Mass |
Striking Load Type |
Barrier Deformation |
Impact Speed |
| 60kg |
Single |
190mm |
48 km/h |
| 120kg |
Loose (individual items not weighing more than 20kg each) |
200mm |
48 km/h |
| 292kg |
Loose (individual items not weighing more than 4kg each) |
190mm |
48 km/h |
But Won't The Rear Seat of Your Sedan, Hatch, Wagon or People Mover Protect You From Loads Inside the Rear Compartment Area?
Interestingly, this is a very common misconception; OE rear seats do not give adequate protection in the event of a heavy object striking the backrest in a high-deceleration accident. The OE rear seat only has to meet a minimum ADR 3/02-5 requirement that it can support a load of 20 times its own mass in a heavy-deceleration accident - this does not allow for any cargo that strikes the back of the seat at the same time. Note that split-folding rear seats generally offer less protection than a fixed-back version.
In a worse case scenario, it is possible for the backrest of the rear seat to collapse or get torn from its mounts. Those passengers in the rear are then crushed against the front seats, and this leads to the possibility of front seat failure; the snowballing danger is obviously quite immense.
And, don't forget - in most wagons, hatches and vans - cargo that's gained enough momentum can quite easily come up and over the top of the rear seat.
Moving away form people carriers, most commercial vehicles - such as trade vans - offer little protection for unsecured cargo. As you could imagine, a loose piece of trade equipment - such as a circular saw - can quite easily become a killer. Recognising this danger, Australia Post and Telstra have had their entire van and wagon fleet equipped with a Milford cargo barrier. There are also many private fleets that have cargo barriers installed - this often helps the employer meet national 'duty of care' laws.
Bonus Protection
A secondary benefit of the Milford cargo barrier is that it serves as a rollover bar. With its strong square cross-section frame, cargo barriers have been seen to prevent the roof caving in the event of a rollover. Milford do not place much emphasis on this 'bonus' protection, but it's clearly evident in photographs such as this...
On that note, we'll let you go out and check what objects are loose inside your vehicle...
Contact:
Milford Industries (ask for Henry Mercieca)
+61 8 8294 5955
http://www.milfordind.com.au/
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