Many readers likely recall the tragic story of Hayden Barnes Ellias, who was killed last year by a falling soccer goal during a team scrimmage. While soccer goal accidents are not very common, a number of children have died from them falling over in the past 30 years or so. The parents of Zachary Tran, who died in 2003, started up an advocacy group called Anchored for Safety whose purpose is to increase awareness of soccer goal dangers and to encourage organizations to properly anchor their soccer goals. Be sure to browse around their site for a lot of tips, ideas, and help for getting goals anchored and secure.
While browsing their site, I came across a scientific paper from Christopher Ferrone related to the design of a safer soccer goal (PDF). Being an engineer, this was very interesting since soccer goals are pretty basic, so I was curious what innovations were contained in the paper.
The majority of U-10 soccer goals are constructed of steel, typically weighing from 150 to 500 pounds. Serious injuries and deaths are a result of blunt force trauma to the head, neck, chest and limbs of the victims. In most cases this occurred when the goal tipped or was accidentally tipped onto the victim2. The intent of the instant design is to prevent or mitigate serious injury or death by developing a more stable soccer goal while considering both reasonably foreseeable uses and misuses.
So is this new design feasible?
On the surface, the design innovation relates to the goal being somewhat deeper than a normal goal (so the rear weight bar is farther back from the pivot point) and the bottom parts of the goal are made of heavy steel bars, providing significant counter weight to any forces an errant child (or wind) my exert on the crossbar or posts. The crossbar and posts are made of lighter aluminum, which has become the norm in today’s soccer goals. The designer wanted to create a goal that could be anchored, but did not need to be due to the design.
One interesting design feature is the use of a 45 degree angled surface at the bottom front of the goal post, which eliminates the corner that would ‘catch’ when a goal tips and instead may allow the goal to slide forward without tipping when, say, a child is swinging on it. Very smart idea.
ÂThe second major difference with many current goal designs is the flexibility of the crossbar. The idea behind this is to reduce impact forces when the goal tips over and increase the force required to start the goal tipping over.
So is this a revoluntionary design? No. It relies mostly on the basic physics that say if the back part of the goal weighs significantly more than the part on the air, it’ll be harder to tip. But it highlights the various options available to try and make goals safer, though there are significant trade offs to consider.
First is the weight. The PEVO 18′ goals our league currently has weigh 162 lbs, while this new design weighs a whopping 241 lbs. That is going to make the goal much harder to move around a soccer complex. With our goals, two adults can move the goals fairly easily. Adding 80 more lbs would probably require three, and possibly four given the imbalance of the weight distribution.
Using aluminum for the posts and crossbar is in line with current goal designs. However, the selection of rectangular posts seems like a step backward. As I highlighted in a post about goal post padding, square posts are more dangerous than round because of the concentration of forces if a player hits the corner (even if it’s “rounded”) and the decreased chance the post will ‘deflect’ the impact like a large 4″ round post can. Now the designer may have chosen rectangular material simply for ease of machining. You likely could use round posts and crossbar in the same design, though they might not be as flexible. I would strongly suggest round posts be in any final design.
I’m also concerned about the flexibility of the crossbar. I understand the intent to lessen impact forces, however the possibility of injury is still there, so I believe any design should worry more about the prevention of tipping than the flexibility of the crossbar. Table 4 shows similar forces at small distances, but inexplicably doesn’t show comparison forces for other distances. So the benefit of the flexible crossbar vs the stiffer crossbars of Goals A & B isn’t readily apparent. I would also be concerned about the impact on game play when balls hit a flexible crossbar.
One thing I saw in the design that I liked was the use of cables to attach the anchors to the goal to keep them from being lost, something I had discussed earlier. Another was the use of nylon lock nuts and tamper proof bolts. Not all goal injuries happen due to it tipping. Some have been due to crossbars falling OFF the posts due to loose or tampered with hardware. When we did our ‘Fix the goals’ day, we were astounded at how loose most of the hardware was. The use of lock washers and nuts, as well as Lock-tite, would go a long way towards ensuring goal hardware stays secure and tight.
I also have a few analytical concerns with the paper. First, the comparison goals (A & B) both lacked ANY type of rear bar. Most goals I’ve seen have a steel bar across the back to provide counter tipping weight. I think it would have been a more realistic comparison to have performed the tests with rear bars on the two standard goals. Our PEVO goals are very lightweight up front due to the posts, crossbars, and support poles being aluminum while the rear bar is heavy galvanized steel. They take a significant force to tip over. If your league has goals without a rear bar, you REALLY should install one – its fairly easy to do. The parts can be obtained from any fence installer (to get the pipe and the pipe clamps to attach to the existing bars). They won’t prevent all tipping of an unsecured goal, but they will definitely make them harder to tip. Rear steel bars don’t lessen the need for anchors, but are an added measure of safety should a goal’s anchors be pulled up/removed.
Next, why were the data tables so incomplete? It would have been interesting to see how both control goals performed at all the points tested with the prototype. I can’t figure out why tests were done only for certain combinations.
Finally, the use of a static force measurement in terms of the force a child or adult can exert on the goal overlooks the prime problem with goal tip overs. Swinging. Most kids hang from the crossbar and swing from it like a set of monkey bars. That swinging force can be substantial, even for a light weight child. So while Table 2 shows significant forces required to tip the prototype, I’d be curious to know what kind of force a swinging body can exert. Instead of balancing the Anthropometric Dummy on the crossbar, I’d have been interested to see how stable the prototype was if you tied the dummy to the crossbar and swung it hard. Given how far the crossbar flexed with the forklift pulling on it – I doubt it would have moved, but swinging still should be accounted for.
I’m not trying to be overly negative here. I think it is fantastic that people spent so much time building and testing a prototype to help improve goal safety. But part of the scientific process is the review and critiquing of scientific papers. What I’ve tried to do here is provide some feedback from a ‘real world use’ point of view, having dealt with our league’s goals and chasing kids off them for years. By far, I think the best thing we can all do is anchor those soccer goals and come up with an industry standard for attaching anchors to the goals.Â