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Crocs Shoe Incident
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Outline of Incident
A young girl stood on the Up escalator with a parent.
On reaching the top of the escalator, the girls shoe was dragged into and underneath the comb plate causing significant damage to the shoe.
The girl managed to remove her foot from the shoe and avoided injury just in time.
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Photograph of shoe in Comb plate.
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Photograph of shoe with comb plate attached.
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Investigation
• A pair of identical shoes were purchased.
• Tests were carried out to prove or disprove theories of how the shoes distorted under load off site.
• Tests were carried out on site to reconstruct the incident and ascertain the actual position of the shoe and the reactions on the escalator when the incident occurred.
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Crocs Shoes
• Upper: croslite resin• Sole: croslite resin
• Durable• Sleek fashionable design
• Lightweight• Non-slip
• Do not retain any odours• Comfortable
• Machine washable• Next day delivery
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Shoe Construction
• Made from Croslite, a proprietary closed-cell resin that moulds to the contours of the feet, these shoes offer an exceptionally comfortable fit. Croslite is lightweight, waterproof, and slip and odour resistant.
• Croslite Resin is extremely soft and malleable which means that some parts of the shoe can get trapped between small gaps. Also, because the resin is “Non-slip” once trapped, it is difficult to release.
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Off Site Investigation
• It was first assumed that the sole of the shoe had moulded into the step tread. The theory was disproved by placing the shoe on an escalator step and then loading 45KG on the toe area of the shoe.
• The following slide shows the shoe in this position. There is little deformation of the sole.
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Off Site Investigation
Shoe under 45KG Load
Sole does not mould into Escalator step treads
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On Site Investigation
• The shoe was taken to the site where the incident occurred and held in different positions on the step.
• It was found that even with the toe of the shoe overhanging the step, it did not get trapped. Please see video 1 on next slide.
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Video 1
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On Site Investigation
• The shoe was then placed on the escalator with the soft toe touching the step riser.
• When the steps come into the transition area, the steps start to level out.
• Due to the very soft “Non-slip” construction of the shoe, it was found that if the toe of the shoe is pressed against the step riser, the shoe “Sticks” to the riser treads and is then trapped between the two steps.
• When trapped, the escalator only moves 2 steps before the shoe is dragged into the combplate. Please see video 2 on next slide.
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Video 2
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Comparisons
The photograph on the left is the actual incident.
The photograph on the right is the result of the investigation on site. Note the similarities.
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Comparisons
• The shoe was dragged into and under the combplate when the incident happened because weight was applied and the shoe could not be pushed back by the riser.
• During the investigation, no weight was put on the shoe but it was still pulled into the combplate and caused significant damage.
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Conclusions
• Soft, rubbery shoes can be caught between escalator steps even if the gaps between the steps are in tolerance.
• If caught between steps, weight applied to the shoe can have detrimental effects.
• When stood on an escalator, shoes should be kept clear of step gaps and risers.
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Recommendations
• To make customers aware of the potential dangers of wearing soft shoes when travelling on Escalators and Travolators.
• To design new safety signs to be located in more prominent positions on Escalator and Travolator entry points.
• To offer the new signs to customers as a “T” package.
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Possible Safety Sign Template
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