Sample Article: Recognizing Red Flags

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Recognizing Red Flags in Slips and Falls

On February 17, 2009, Sue Smith was walking on a barrier free access ramp between the roadway and the sidewalk of a shopping plaza when she reportedly slipped and fell on ice that was on the sidewalk/ramp.  As a result of her fall, Ms. Smith reportedly sustained injuries to her face and knee cap.

You are asked to evaluate her claim and decide whether Sue Smith’s injuries are consistent with the accident. As a claim’s adjuster it is important to understand the complexity of slips, trips and falls especially when there are people who claim injury or try and assign blame for a pre-existing condition.

Below are some potential ‘red flags’ to look for when reviewing your claim to help you determine causality and responsibility for an accident, especially in these winter months when ice can be prevalent.

Causes of falls

There are many reasons why pedestrians fall down. However, the most common are slip events and trip events.


As a pedestrian walks, he or she generates both vertical and horizontal forces where his or her feet contact the ground. A walkway surface must have sufficient friction to resist the forward horizontal forces generated while walking in order for it not to be slippery.


In comparison, when a pedestrian trips, it is because a difference in elevation has stopped the foot from moving forward during the swing-through phase of the human gait cycle.

If the toe of the swinging limb strikes an obstacle at this moment the chance of falling is high, as the centre of mass of the body is at or forward of the toe of the contra lateral support foot and the momentum of the body carries the body forward, resulting in a fall by the pedestrian.

Slipping versus Tripping Injuries

Since the dynamics of a pedestrian trip are different from the dynamics of a pedestrian slip, not only are the falls different, but so are the expected types of injuries.  This is why you need to ensure that Sue Smith’s claimed injuries are consistent with her reported incident.

Typical Slip Injury

When a slip of sufficient length occurs causing a loss of balance, the pedestrian tends to fall backwards, straight down on their back or buttocks, or slightly to the side.  Besides injuries to the hand/wrist from attempting to break the fall, the twisting of the knee and ankle as the weight of the body lands on these joints can also lead to injuries to connective tissue as the joints are stressed immediately prior to and during the landing.  Fractures to the bones at/near the foot are also consistent with a slip.  Slips may result in a higher frequency of tail bone fractures when compared to other types of fall dynamics.

Typical Trip Injury

Trips will result in the person falling forward. In this case the pedestrian will tend to extend his or her hands to ‘break’ the fall and injuries to the hand/wrist are common, but also injuries to the shoulder are more common than for slips. Impact injuries to the knee are also expected for a trip.

In some cases if reaction time is insufficient a pedestrian may land on his or her face, as may be typical with the elderly.

Therefore if a claimant states they slipped on ice but report injury to their kneecap (patella) that may be a warning (‘red flag’) to investigate the claim further.

Slip Resistance

The static coefficient of friction (COF) is a measure of how slippery a surface is.  For level walkways, the industry accepted standard minimum static COF for a surface to be considered slip resistant is 0.5 using a ‘standard’ traction test pad.  This includes a safety factor such that other foreseeable activities may be undertaken on a walkway, such using differing footwear, turning while walking, and jogging.

Snow, by itself, usually provides adequate slip resistance for walking

However, ice has a significantly lower COF to a polymer sole typical for a winter boot.  This is a significant risk for a slip and fall and is considered hazardous.

If Sue Smith claimed that she slipped on a snowy sidewalk while walking at a ‘normal’ pace, and that there was no ice, this should be a ‘red flag’.

Foot Displacement to Cause Fall

Since the majority of slips occur during the heel strike of human gait, a slip may occur on an area with inadequate slip-resistance as small as approximately 35 mm (1 ½ in.) across.

A very small slip does not have to result in a fall.  For example, a slide of 5 mm (¼ in.) will not typically cause a person to lose his or her balance.

If an area deemed ‘slippery’ is less than approximately 10 cm to 15 cm (approximately 4 in. to 6 in.) in length, it will not typically allow a pedestrian to slide a sufficient distance to cause a loss of balance and fall.

This information can be useful if a claimant states that he or she slipped on a patch of ice that was 5 cm (2 in.) across.  If the patch of ice was, in fact, only 2 in. in diameter, the risk of a fall due to a slip is unlikely, and this would be another ‘red flag’.


Ramp slopes change the ratio of horizontal and vertical forces compared to walking on level surfaces. A surface with a downward slope would behave as if it were more slippery than if the surface was level.

This is important because if someone walks from level to decline there is a change in effective traction that significantly increases the risk of a slip.  Conversely, stepping onto an incline reduces the risk of a slip.

Ms. Smith claimed she slipped while walking towards the mall. Therefore she would have been travelling up the incline of the ramp at the time of her accident.  If Sue Smith claimed that she slipped with her first step onto the ramp, this would be a ‘red flag’, since this is not an expected scenario for a slip.

However, if Sue Smith claimed that she slipped after taking several steps on the ramp, this would be a more likely location for a slip.  BUT, unlike most slips that occur at heelstrike of the human gait cycle, this slip would be expected to be at toe-off.  Of course, the type of injury from a slip at toe-off is often different than with a heelstrike slip.

Meteorological Information

In the above noted scenario Ms. Smith claimed that she slipped on a patch of ice. Review of the relevant meteorological data would be required to determine whether there was rain or snowfall days and hours preceding the incident and to what degree.  When determining causality, understanding the weather conditions and how they may or may not have contributed to the incident are important considerations.

If Sue Smith’s claim is filed days, weeks, or even months after the reported incident then it is likely that any evidence of ice or other slippery conditions at the mall will have disappeared.  That is why review of the meteorological data is important to determine how ice (if any) formed, and when it likely formed.

If the weather data is not consistent with the formation or presence of ice, another ‘red flag’ has arisen.

Or, if the weather data indicates that ice could have formed several days prior to the date of loss, there might be the ability to apply some contributory negligence to a third-party contractor overseeing sidewalk/parking lot maintenance.


Understanding the myriad of elements involved in what may seemingly be a straightforward slip and fall case can be surprisingly complex.  However, we hope that this article will allow you to identify ‘red flags’ (based on fall dynamics, injury, surface conditions, etc.), so that likely legitimate claims can be settled quickly, and questionable claims properly investigated.

P.S. Knee cap AND facial injuries slipping going UP a ramp?  Despite multiple red flags these injuries could have occurred if her fall was at the middle or top of the ramp.