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accident reconstruction · forensic engineering

Slip & fall failure analysis.

A fall happens in under a second. Proving what caused it — a friction deficiency, a walkway defect, a lighting failure, or a code violation — takes measurement, not speculation.

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A fall is a loss of balance the body could not recover from, and the physical question is always some version of why: because the floor offered less traction than the gait required, because a walking surface changed elevation without warning, because a stairway's risers were not uniform enough for the rhythm a descending gait depends on, or because a handrail that should have caught the fall was not there to catch it. Each of those has a measurable signature — coefficient of friction, height differential, riser and tread dimensions, illuminance — and each measurement decays with time as floors get refinished, ice melts, and stairs get repaired. The forensic task is to capture that signature as close to the incident conditions as possible and test it against the applicable code.

mechanisms

How slips, trips, and falls happen.

Falls are grouped by the specific condition that removed the margin a normal gait relies on.

Coefficient-of-friction deficiency

A floor finish, wear pattern, or contamination reducing traction below the level a normal gait requires, particularly in transition zones and when wet.

Walkway surface defects

Cracks, height differentials, uneven pavers, or abrupt transitions creating a trip hazard not visible at a normal walking pace.

Stairway geometry non-compliance

Riser height or tread depth variation, or a defective nosing, disrupting the consistent rhythm a descending gait is built around.

Handrail & guard deficiencies

A missing, discontinuous, or improperly sized handrail removing the recovery mechanism a person reaches for after a misstep.

Lighting deficiency

Illumination below the level needed to perceive a level change, an edge, or a hazard in time to adjust gait or step placement.

Foreign substance & housekeeping failures

Spills, debris, or weather accumulation such as ice or snow that was not identified or remediated within a reasonable time.

methodology

What the evidence shows — and what we examine.

Slip-and-fall work depends on measuring the actual surface and geometry involved, ideally before it changes, and comparing those measurements against code.

Tribometry / COF testingDynamic and static coefficient-of-friction testing of the actual walking surface, in both wet and dry conditions.
Surface profilometryMeasuring height differentials, slopes, and surface irregularities against applicable code tolerances.
Stairway & handrail dimensional surveyRiser, tread, nosing, and handrail measurements evaluated against IBC and ANSI A117.1 requirements.
Lighting level measurementIlluminance readings at the fall location compared against code minimums for the space type.
Video & incident timeline analysisSurveillance footage analysis for gait, hazard exposure time, and evidence of prior notice.
Maintenance & inspection record reviewHousekeeping logs, inspection schedules, and prior incident or complaint history establishing notice.
what's at stake

A single misstep, a premises-liability case.

Fall cases carry consequences well beyond the injury itself:

hip fracture, TBI, or spinal injury premises-liability litigation comparative-negligence disputes building-code compliance exposure commercial & retail business interruption insurance & workers-comp claims

Test the surface before it changes.

Floor finishes get reapplied, ice melts, and stairs get repaired. Coefficient-of-friction and dimensional measurements are only meaningful if taken at or near the condition that existed at the time of the fall.

common questions

Slip & fall — the questions we hear.

How is coefficient of friction measured after the fact, and does it hold up in court?

With a tribometer, tested under both wet and dry conditions using recognized ASTM test methods on the actual walking surface. Results hold up best when testing occurs promptly and on the same surface in a condition representative of the incident — the same finish, the same wear pattern, the same contamination if reproducible. Testing conducted long after a floor has been refinished or replaced is far more vulnerable to challenge, which is why early testing matters.

What building codes govern stairway and handrail dimensions?

The International Building Code and ANSI A117.1 set riser height, tread depth, nosing, and handrail height and graspability requirements, and most jurisdictions adopt a version of the IBC with local amendments. Uniformity between risers within a single flight is often as important as the absolute dimensions, since a single outlier riser in an otherwise uniform stair is a well-documented fall trigger.

How do you prove the property owner had notice of the hazard?

Through surveillance video showing how long the hazard existed before the fall, housekeeping and inspection logs showing the last check of the area, prior complaint or incident records for the same location, and — for a spill or substance — physical evidence of its condition (tracked footprints, drying pattern) that can support an estimate of dwell time. "Constructive notice" arguments turn heavily on how long the hazard was actually present.

Can weather-related falls on ice or snow still support a claim?

Often yes, depending on the jurisdiction's treatment of natural versus unnatural accumulation and any local ordinance setting a remediation timeframe. An unnatural accumulation — ice from a defective gutter or downspout, or refreeze from an inadequate drainage slope — is generally treated differently than a naturally occurring snowfall the property has not yet had a reasonable opportunity to clear.

What should be documented immediately after a fall?

Photographs of the exact surface and any hazard before conditions change, the footwear worn at the time, witness contact information, an incident report, and a written request to preserve any surveillance video before it is overwritten — most systems recycle footage within days to weeks. If the surface can still be tested in a representative condition, that should happen as soon as possible.

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failure-analysis assistanttriage · not a substitute for an expert
I can help scope a fall incident — likely causes, what to test or preserve before conditions change, and which expert fits. What happened?