Underride guards might have saved the Tesla driver, but are they practical and realistic?

testing safe liner
© Krone/ Testing a Safe Liner in side-underride collision. In real life, it was not so successful.

We have written earlier that the Tesla driver killed in autopilot crash might still be alive if trailers had side underride guards, and about the tragic deaths of Marianne Karth’s two daughters in a rear underride crash.

Around the time Joshua Brown’s Tesla went under the side of a trailer, Karth and other advocates were meeting in the first Truck Underride Roundtable, a group trying to improve standards of underride protection. The National Highway Traffic Safety Administration is looking at the rules, and Mrs. Karth and the Truck Safety Coalition have made submissions demanding stronger rear underride protection and the requirement for side underride guards.

The Truck Trailer Manufacturing Association (TTMA) has commented on these, and on the demand that trailers be equipped with underride side guards. (TreeHugger has been advocating for sideguards for years to protect cyclists and pedestrians, but has not previously followed the activities relating to car underride protection.)

In an earlier 2004 study on sideguards done by the industry, it was estimated that they would weigh about 750 pounds and cost $ $1560. That doesn’t sound like much, but would increase fuel costs and reduce payload, and therefore income. Add it all up and they say they would cost the industry $573 million annually. And those are 2004 dollars! Divided by the number of deaths it would prevent, (they claim 11) it comes to $47 million per life saved, which is not “cost beneficial.”

However research by the Association for the advancement of Automotive Medicine comes up with significantly higher numbers, which no doubt change the economics. (PCI stands for Passenger Compartment Intrusion).

side fatalities© Study: Estimating Side Underride Fatalities Using Field Data

There is yet another study that concludes that even those numbers determined by Fatality Analysis Reporting System (FARS) are underestimating the deaths caused by side underride collisions. So the economic cost per death is a lot lower than $47 million per person. It is doubtful that the cost to the industry is half a billion dollars too. But we are still talking big numbers.

Safeliner truck© Krone Safe Liner

The TTMA notes that European precedents don’t apply because their trailers are built differently than North American ones, more like flatbed trucks with big substantial rails underneath (this true, they are really like flatbeds with fabric sides) whereas North American trucks are monocoque construction with lighter rails below. American trailers also have sliding tandem axles at the rear, that are moved to adjust for loads. There are significant technical challenges.

They also claim that the Krone Safe Liner trailer, discussed in our previous post, is “technological and commercial failure.”

Due to the increased rigidity in the trailer structure that resulted from the added frame supports, the trailers were less flexible when operated over uneven road surfaces or on surfaces that produced twisting forces. Cracks began to appear in the major beams and cross members. Safe Liner trailers became disabled during highway use and presented safety risks to other motorists….KRONE eventually concluded that the Safe Liner design was not technologically feasible and presented a risk of major accidents, so in 2003 it discontinued production and repurchased these trailers from its customers.

sideguard design© Google Patent

The TTMA also looked at an American aftermarket side underride protection system designed by Bruce E. Enz John E. Tomassoni Angela Trego, and made a persuasive case that this is also problematic. Others, like the Underride Network, make the case that it is technically and economically feasible.

So where does that leave us? Confused and concerned. The fact remains that, as I noted in the earlier post, the designs of our cars and our transport trailers are fundamentally incompatible. Our cars are designed with air bags and crush zones that are useless against trucks; as one activist noted, you are safer driving into a brick wall than into the side of a trailer.

The death of a famous actor caused a big change in the rules that made rear underride protection mandatory; perhaps this well-publicized crash will bring a change in the thinking about side protection. Perhaps if this was something that was thought of at the design stage of the trailer instead of being an add-on, there might be a technical and cost effective solution that works.

Instead, The TTMA wants the car manufacturers to take the lead on this, suggesting that “crash avoidance technologies are rapidly developing for passenger vehicles that may prove both technologically feasible and cost- beneficial for all types of collisions, including collisions into the sides of trailers” - we have just had a demonstration about how that might play out.

Tags: Tesla Motors | Transportation


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