# At the End of a Slippery Slope: A Pilot Study of Deceleration Mats for Snow Tubing
## 4 Discussion  
### Measurement Values  
In this study, we conducted on-slope measurements of snow tubing to analyze the effects of deceleration mats in the run-out area of a snow tubing lane. We found that deceleration mats were effective at slowing snow tubes and riders when compared to not having deceleration mats; the mats increased the peak deceleration by a factor of 5 for the _flat_ condition and almost 8 for the _folded_ condition compared to the _no mat_ condition. Consistent with this, the effective (average) COF increased with deceleration mat use and was amplified when the mats were in the _folded_ configuration. Though the deceleration increased significantly with mat use in our tests, it did not cause the riders to become unstable or fall off the snow tubes. Traversing the deceleration mats did not produce observable movement between the riders and snow tubes (from the video) and we measured less than 2.5 cm of fore-aft motion between the rider and snow tube when traversing and exiting the deceleration mats. Deceleration mats slow but do not destabilize riders. The measurements in this study agreed well with data published on friction between other materials and snow. It was expected that the effective coefficient of friction (COF) for the snow tubes on the snow would be low in order to allow riders to accelerate downhill. The average COF for snow tubes on snow was in the range of other snow sports equipment  
Figure 3: (**a–c** from **left** to **right**) Participant descending the snow tube run and traversing the deceleration mats that were in the _folded_ configuration. When the deceleration mats were folded (regardless of the side—_ribs_ or _projections_—presenting to the snow tube), the snow tube and rider compressed the folded section as they moved past. (**d**) Close-up of the compression of the folded portion of a deceleration mat. on snow; see Table 2. The effective COF of the snow tubes on the deceleration mats was similar to or less than ski suit fabrics on snow, footwear on snow, rubber on ice, or tires on ice. There was improved stopping ability with the _folded_ mats compared to the _flat_ mats. Unlike folding the mats, there was no trend produced when changing the geometric protuberance on the mat surface (_ribs_ vs. _projections_) presenting to the snow tube in our tests. Because we flipped or exchanged the mats before each test and presented a clean mat surface for the snow tube to contact, our study provided the best-case scenario for deceleration and for observing differences produced by the surface protuberances. In many tests, snow was pushed onto the deceleration mat by the snow tube and rider. Though we did not quantify the snow remaining on the mats after each test, the snow pushed onto the mat was unaffected qualitatively by the surface protuberances. Interestingly, the _folded_ mats often shed naturally most of the snow that was pushed onto the mats in the tests. This occurred when either the mat unfolded after the snow tube moved fully past or during the decompression of the folded section. This \"self-cleaning\" ability of the _folded_ mats may be useful for busy snow tubing operations or when it is actively snowing and may help produce more repeatable rider deceleration. The kinematic data prior to the run-out area showed low frequency vibrations at the pelvis (near the COM), not unlike those found in other snow sports [11]. In the _folded_ mat tests, the snow tube riders bounced slightly in the vertical direction after they passed the fold, producing a small vertical component of acceleration. This vertical component of acceleration was within the range observed prior to the run-out area during natural vibrations. The vertical component of acceleration could be attributed to the slight drop (on the order of 5 cm) from the double layer of mat at the fold. Despite this bounce, there was no significant increase in the pitch angle of the riders as they traversed the deceleration mats when compared to the _flat_ mat condition. We hypothesize that the pitching motions