As a premises liability expert, I am often asked a deceptively simple question: In a slip and fall accident, how do you determine whether a property was truly unsafe?

The answer lies at the intersection of data, standards, and the field of tribometry. Tribometry is the scientific measurement of friction between surfaces. In slip and fall cases, that means measuring the slip resistance of the walking surface. The goal is to quantify slip resistance rather than relying on subjective descriptions like “slick,” “slippery,” or “seemed unsafe.”

Slip and fall cases are sometimes dismissed as minor accidents or unavoidable mishaps. In reality, the data tells a different story. Falls are among the leading causes of injury-related emergency room visits in the United States, resulting in significant human and economic costs. Properly evaluating these incidents requires both experience and the right tools.

In this article, I’ll explain how tribometric testing, ASTM standards, and objective data transform slip and fall evaluations from subjective speculation into defensible science. Whether you’re evaluating a potential case or defending against a claim, understanding this process is essential.

Tribometer used to measure friction in slip and fall cases

Slip and Fall Statistics: Understanding Premises Liability Cases

Fall-related injuries represent a substantial public safety concern. According to the
NEISS All Injury Program, operated by the Consumer Product Safety Commission (CPSC):

Approximately 8 million people per year are treated in emergency rooms due to falls
Roughly 40,000 deaths per year are attributed to fall incidents
Falls account for 29% of all nonfatal emergency room visits, making them the leading cause of such visits

These slip and fall accidents occur across all property types: commercial buildings, residential complexes, public spaces, and workplaces. When they happen on someone else’s property, they raise premises liability questions: Did property conditions contribute to the fall, and if so, was the hazard foreseeable and preventable?

The Enormous Cost of Falls

Beyond human suffering, falls impose an enormous economic burden, one that is often overlooked in individual premises liability cases.

Based on commonly accepted cost estimates:

Fatal fall injuries
- $8 million per fatal injury event
- × 40,000 deaths per year
- ≈ $320 billion annually
Non-fatal fall injuries
- $80,000 per non-fatal injury event
- × 8 million non-fatal falls per year
- ≈ $640 billion annually

Each slip and fall accident carries significant costs. Combined, fall-related injuries represent nearly one trillion dollars per year in societal cost. These figures highlight why property owners, insurers, and courts must take walkway safety seriously and why expert evaluation matters.

Why Slip and Fall Cases Require Expert Analysis

In many slip and fall cases, the central dispute is not whether someone fell, but why they fell and whether the condition of the premises played a material role.

A premises liability expert helps by:

Translating complex safety issues into objective findings
Determining whether a walking surface met accepted safety standards
Evaluating whether a hazard was foreseeable and preventable
Providing scientifically grounded opinions rather than speculation

This is where tribometry becomes essential. For example, a property owner might claim a floor “looked fine” while a plaintiff insists it was “extremely slippery.” Tribometric testing resolves this dispute with data.

A measured coefficient of friction (COF) provides objective evidence that either party can rely on. A reading below 0.5 may support claims of inadequate slip resistance, while a reading above this threshold may demonstrate the surface met accepted safety standards.

This objective measurement transforms the evaluation from competing opinions into defensible science, regardless of which party the data ultimately supports.

Making Sense of Slip and Fall Cases Through Tribometry

Tribometry allows experts to answer critical questions such as:

Was the surface reasonably slip resistant?
How did contaminants (water, grease, cleaning solutions) affect traction?
Did the surface comply with recognized safety standards?

Slip Resistance Testing: Evaluating Walkway Safety

Walkway safety is not guesswork. Using tribometry for slip resistance testing, an expert can objectively evaluate:

Flooring materials (tile, concrete, wood, coatings, mats)
Surface wear and maintenance conditions
Environmental factors such as moisture or debris
Changes in friction due to cleaning methods or surface treatments

By collecting real data from the walking surface, or a substantially similar surface, we can assess whether the walkway presented an unreasonable risk.

Performing a Risk Assessment

Tribometry supports a broader risk assessment, which considers:

Likelihood of a slip occurring
Severity of potential injury
Frequency of pedestrian traffic
Whether reasonable safety measures were in place

This structured analysis helps determine whether a property owner met, or failed to meet, their duty of care.

We worked on a case several years ago involving an older woman who slipped on spilled shampoo in a retail store. Contaminants like liquids on walking surfaces are well-known to reduce friction to unsafe levels.

The legal question wasn’t whether shampoo reduces traction (it does) but whether store employees adequately searched for and addressed hazards like spilled liquids.

In a case like this, Tribometric testing would measure the slip resistance when there is a contaminant present, for example, quantifying how significantly shampoo reduced surface friction. This kind of objective data helps attorneys and experts in evaluating whether spills represent a foreseeable hazard that should have been discovered and remediated through reasonable inspection procedures.

Understanding the Standards: ASTM F13

As a slip and fall expert, understanding applicable industry standards is fundamental to any evaluation. Most notably, ASTM F13, the committee on pedestrian/walkway safety, provides guidance related to slip resistance, testing methodologies, and safety considerations.

ASTM F13 standards help establish:

Accepted testing practices
Appropriate interpretation of friction measurements
Industry consensus on walkway safety principles

In any premises liability case, standards provide an essential framework for evaluating whether conditions were consistent with accepted safety practices.

The Importance of Certification: English XL Tribometer and CXLT

The CXLT Certification Program

At Alpine Engineering & Design, myself and other premises liability experts hold CXLT (Certified XL Tribometrist) certification because it strengthens the technical rigor and defensibility of our evaluations. This certification program focuses on the proper use of the English XL (ExCel) tribometer, emphasizing accuracy, repeatability, and defensible testing methods.

The certification ensures that:

Testing is performed correctly and consistently
Results are scientifically valid and reproducible
Opinions are grounded in recognized methodology

How the English XL (ExCel) Tribometer Works

The English ExCel tribometer is a biofidelic testing device, meaning it closely replicates the biomechanics of a human heel strike during walking.

Key characteristics include:

Simulates realistic human gait dynamics
Measures slip resistance
Designed to reflect real-world slip potential
Widely recognized in forensic walkway evaluations

Because it mirrors how people actually walk, the English XL provides meaningful data that connects directly to real-world slip risk.

Experience Enhanced by Certification

While I had extensive experience in premises liability expert work before obtaining the CXLT certification, this additional training has made me more capable and more precise in evaluating walkway safety and slip and fall claims.

Certification enhances:

The technical rigor of my evaluations
My ability to explain findings clearly to attorneys, insurers, and juries
The defensibility of my opinions under scrutiny

In a field where outcomes often hinge on details, combining experience with certified, biofidelic testing makes a measurable difference.

Conclusion

Slip and fall cases are far more than routine accidents. They represent a leading cause of injury, death, and economic loss in the United States. Making sense of these cases requires more than intuition. It requires science, standards, and specialized expertise.

Through tribometry, adherence to ASTM F13 principles, and certified use of tools like the English ExCel tribometer, premises liability experts can provide objective, reliable insights into walkway safety. Ultimately, this approach benefits not only the legal process but also public safety itself.

About Alpine Engineering & Design

Alpine Engineering & Design is a multidisciplinary engineering firm providing expert analysis and testimony in complex legal matters nationwide. Our team includes slip and fall experts and premises liability specialists who evaluate slip and fall incidents using tribometric testing and standards-based walkway safety analysis. We also support attorneys and insurers in forensic engineering investigations, workplace accidents, equipment failures, and building-related claims, delivering clear and defensible engineering opinions.

Frequently Asked Questions

What should I look for in a slip and fall expert evaluation?

A credible evaluation uses calibrated instruments, follows ASTM testing protocols, and documents conditions thoroughly. Look for experts with relevant certifications like CXLT who can explain methodology clearly. The evaluation should provide objective measurements, not opinions, and analyze findings against recognized safety standards to produce defensible evidence for litigation.

What is tribometry and why does it matter in slip and fall accidents?

Tribometry is the scientific measurement of friction between surfaces. In slip and fall cases, a tribometer measures the friction of the walking surface to determine slip resistance objectively. This provides measurable evidence about whether a surface presented an unreasonable risk, moving beyond subjective descriptions.

Do I need a slip and fall expert for my case?

If your case involves disputed surface conditions, questions about maintenance practices, or claims that a walkway “looked safe,” you likely need expert evaluation. Slip resistance testing provides objective data that resolves disputes between competing accounts. Attorneys on both sides often engage experts early to determine case strength before investing in litigation.

What evidence does a slip and fall expert collect?

Experts document surface materials, measure slip resistance using calibrated tribometers, photograph conditions, test for contaminants, and evaluate maintenance records. They analyze data against ASTM standards to determine if surfaces met accepted safety thresholds. Early expert involvement preserves critical evidence before conditions change or surfaces are repaired.

What makes a qualified slip and fall expert witness?

Look for engineering credentials, specialized certifications like CXLT, experience with tribometric testing, and familiarity with ASTM standards. The expert should explain complex technical concepts clearly and have a track record of defensible testimony. Their methodology must follow recognized standards to withstand scrutiny under cross-examination.

Evaluating Slip and Fall Cases: A Premises Liability Expert’s Approach