Tommy Pettersson and the Journey of the Swedish Plus Test

Tommy is a Senior Advisor, now on a consultancy/ part-time basis for VTI (the Swedish Transportation Authority). Tommy has been at VTI since 1984, working in the Swedish car seat facility, where he headed up the crash element from 2004 to 2020, when he ‘retired’. Tommy has been influential Worldwide in focus groups pertaining to child safety and legislation, and has been at the forefront of advancing the level of car seat safety. Tommy was Sweden’s representative for the creation of regulation R129 which took 4 years to create and implement. While still working on a number of other projects, it is child car seat safety that he is mostly recognised, and most ‘famously’ for his work in creating the Swedish Plus Test.

The reason for the Plus Test and where it came from

Tt was during the infancy of the space program, and their learnings that culminated in the beginning of rear-facing (back in the 1960’s). It was then that it was recognised that it was essential to rear face to be able to withstand the forces put upon the human neck during acceleration… and rear-facing was born… although for adults.

Almost immediately after this, it became apparent to Swedish design engineers that this learning could be embraced into safety equipment, and shortly after that ‘Sweden’ created the first prototype of a rear-facing child car seat – they were able to crash test that prototype around 60 years ago. During the 60’s and 70’s, there was much ongoing testing, discussion and thought on this new-found methodology. Tests took place with test dummies that had load-sensors to measure acceleration in the head and in the chest. The results prove that when forward facing with a harness, the level of acceleration in the head was significantly higher than in the chest than it was when they did the equivalent test rear facing.  It was becoming apparent that the results were crystal clear – rearward facing was vastly superior in its safety results! At this time, the Swedish Transportation Authority (at that time, called TSI) wrote a regulation around their findings, and called this regulation, the ‘T Approval’ – the T Approval came into force in 1975, and placed into Swedish car seat law. With that change in Swedish car seat law, the only seats that could be used in Sweden were T-Approved Seats; rear-facing seats. It just simply became culture in their country, and just how Swedish car seats were – peoples expectations were set, and the general perception was simply that that’s just what a car seat was. Simply put, with rear-facing; they got it!

Unlike in ECE regulation R44, the T approval had a movement limit for the head – R44 did not. Sweden pushed hard for this limit to by applied to regulation, but it was resisted by other countries and not added to ECE regulation. Moving forward to the planning and creation of regulation R129, there were some good (but modest) steps forward –  the law would change to implement a minimum age for rear-facing to 15 months – while this was still extremely young, it was at least something – most of Europe found this revolutionary (!?!). Unfortunately, though, there were still no load limits in the neck to be tested in R129 at that time, and still to this day.

Change in Swedish Car Seat Law….

In Sweden, it was always common for products to have ‘double approval’. The Swede’s are naturally, extremely considered people, particularly when it comes to safety – in car seats, they would use the T Approval, in conjunction with ECE approval as standard; R44 and laterally R129 – having the double approval would give the Swedish people the confidence in a product, and confirm that its safety was not questionable.

In the mid 90’s, Sweden joined the EU, and under EU law, you are not permitted to have your own country regulation – EU rules will apply. In car seats, Sweden resisted this rule and persisted with the double approval ruling all the way through to 2008. In 2008, there was a challenge to this defiance, and Sweden was finally forced to drop the ‘double approval’ to align with the rest of the EU – as a result, Sweden’s country law had to change, dropping the T-Approval from law, and only run with either of R44/R129. Tommy insisted that a solution HAD to be found. He sat down for hours, then came up with an idea – the Swedish Plus Test!

What is the Plus Test and how could he implement it?  

The Plus Test was more or less just like a modern version of the T Approval: it had a more adaptable test dummy – a little higher speed than regulation (56.5km per hour) – higher grade of deceleration (shorter stopping distance – the shorter stopping distance applies significantly more force on the car seat than regulation level testing) – measuring of, and setting a limit to the neck forces – a voluntary test. It was the rate of deceleration that really set the test apart, rather than the speed. The level of force exerted in this traumatic breaking was stark, in comparison to standard testing.

Being a voluntary test, the EU were not in a position to prevent this new Plus Test, as it was more just an optional accolade that a seat could attain – some might say; A badge of honour!

Once he’d formalised the test, Tommy started to contact manufacturers to offer this voluntary test, and he had immediate uptake. In Sweden, the car seat culture still expected a ‘double approval’ in some way, shape or form; and as a result, he knew that the buying population would seek it out. In 2009 the Plus test went into force – the test continued to use the current (at the time) P crash test dummy, with the addition of load sensor in the neck. While the Plus Test wasn’t a legal requirement, it was a standard that was expected, and it was adopted by the population.

In 2023, a new version of the Swedish Plus test had to be written – the evolution of time meant that the balance had tipped, and the vast majority of seats on the market were now R129 (test) regulated, with the phase-out of any new releases of R44 car seats. During the process of R129 testing, it’s a (crash test dummy called the) Q series dummy that is used, so it felt imperative to base the test now on the newer technology. The Q test dummy had significantly more technology built into it than the P dummy and had now become the standard used in regulation. P dummies were phased out with R44, so it had become apparent that the testing should evolve and be modelled with the same test equipment.

The new Swedish Plus Test: there really weren’t too many changes to the test other than the change in test dummy. There were a couple of subtle changes in the revised version: the test bench that the seat sits on and completes the ‘crash’ is a slight variation on its predecessor – mainly just a tweak in the angle of the bench.

The previous Plus Test measured the ‘stretch’ on the neck (at point of collision), although it was being established that the necks compression caused in a crash could also have as detrimental an effect on a child, and therefore tolerances were also added to the criteria.

There is now a provision to cater separately for 105cm seats and 125cm seats.

Now, only rear-facing seats can be submitted into the test.

There is much more that could be written about Tommy Pettersson and the Plus Test and the positive impact that came about to child safety as a result of Tommy’s input, although this overview will give an overview to the outline points, where it came from and the recent changes.

We thank you Tommy for all that you’ve done.

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