Slip resistance of winter footwear on snow and ice measured using maximum achievable incline

Figures & data

Figure 1. Test footwear. Six styles of footwear were selected for testing including a running shoe (Style-S), an indoor slip-resistant boot (Style-K) and four winter boots.

Table 1. Test footwear.

Footwear	Make/model	Details
Style-S	Athletic works Ted Men’s jogging shoes, Walmart Canada Corp., Mississauga, Canada	Running shoe with thermoplastic rubber outsole
Style-K	Keuka SureGrip®, Tennessee, USA	Low-cut ankle boot developed for slip resistance on industrial surfaces
Style-I	Arctic Ice Boot, SureGrip®, Tennessee, USA	Winter ankle boot with rubber outsole designed for slip resistance
Style-N	Outsole and upper: Dakota, Mark’s®, Alberta, Canada	NCI rubber compound outsole; Outsole tread identical to Style-G; Uppers identical to Style-G and Style-J
Style-G	Outsole: Green Diamond Tire, Colorado, USA; Upper: Dakota, Mark’s®, Alberta, Canada	Outsole consisted of aluminium oxide and silicon carbide granules embedded in rubber to enhance underfoot traction; Outsole tread identical to Style-N Uppers identical to Style-N and Style-J
Style-J	Outsole: JStep Sole, Gimhae, Republic of Korea; Upper: Dakota, Mark’s®, Alberta, Canada	No tread and outsole created using a sheet of a proprietary JStep compound; Uppers identical to Style-N and Style-G

Figure 2. WinterLab test conditions. (a) Tilting WinterLab to create slopes; (b) dry and wet ice walkways; (c) walking over the snowy walkway; (d) snow accumulation underfoot; (d) walking in the snow condition on dry ice after walking in soft snow.

Figure 3. Performance of test footwear rated by the maximum achievable incline angle. The secondary axis shows COF values equivalent to the incline angles.

Table 2. Estimated means of gait kinematic data (mean (SE)) at each level of the main effects of slope type, footwear, and surface.

		Step length (m)	Step time (s)	Step speed (m/s)	Step width (m)	Foot angle (°)	Upper body flexion (°)
Slope	Level	0.52 (0.02)	0.67 (0.02)	0.79 (0.03)	0.11 (0.01)	17.2 (0.9)	0.1 (2.1)
	Ascent	0.44 (0.01	0.84 (0.04)	0.56 (0.03)	0.09 (0.01)	8.6 (0.7)	11.3 (2.8)
	Descent	0.40 (0.01)	0.66 (0.03)	0.63 (0.04)	0.12 (0.01)	11.1 (0.7)	−5.5 (2.4)*
Footwear	K	0.45 (0.01)	0.73 (0.02)	0.63 (0.02)	0.10 (0.01)	10.8 (1.0)	2.2 (2.5)
	S	0.47 (0.01)	0.70 (0.03)	0.69 (0.03)	0.10 (0.01)	13.1 (0.7)	1.6 (2.3)
	G	0.46 (0.02)	0.74 (0.03)	0.65 (0.04)	0.11 (0.01)	12.4 (0.7)	1.4 (2.8)
	N	0.46 (0.01)	0.71 (0.02)	0.67 (0.03)	0.11 (0.01)	12.7 (0.9)	2.2 (2.8)
	I	0.45 (0.02)	0.72 (0.03)	0.66 (0.03)	0.10 (0.01)	10.8 (0.8)	1.7 (1.7)
	J	0.46 (0.01)	0.74 (0.03)	0.65 (0.03)	0.12 (0.01)	14.0 (0.5)	2.8 (2.2)
Surface	Dry ice	0.46 (0.01)	0.75 (0.02)	0.64 (0.03)	0.10 (0.01)	12.6 (0.70)	0.3 (2.5)
	Wet ice	0.46 (0.02)	0.71 (0.03)	0.67 (0.04)	0.11 (0.01)	11.7 (0.55)	5.7 (2.4)
	Snow	0.16 (0.01)	0.72 (0.03)	0.67 (0.04)	0.10 (0.01)	12.7 (0.86)	−0.1 (2.5)*

Note:

Factors which were found to have significant main effects are highlighted in grey.

* Negative flexion angles indicate that the upper body was in extension.

Figure 4. Interaction graphs for significant two-way interaction effects. (a) Surface–slope interaction for heel strike foot angle; (b) Surface–slope interaction for upper body flexion angle; (c) footwear–slope interaction for upper body flexion angle.

Figure 5. Dynamic COF measured during bench testing. The secondary axis shows incline angles equivalent to the COF values.

Figure 6. Results from the maximum achievable incline angle testing compared to bench testing on the dry and wet ice conditions.