Anatomy of a Fall: Defending Slip Trip and Fall Cases: Essential Technical Background for Construction Lawyers

Trip Hazards

Trip accidents occur when a person’s foot collides with an object, causing the person to lose their balance and fall. These accidents occur most frequently at sidewalks, stairs, ramps and curbs—locations where there is a change in elevation of the walking surface. A key first step in a trip and fall accident investigation involves documenting the as-built conditions to determine if the conditions conform to applicable codes and standards.

For sidewalks and other flat walking surfaces, permissible changes in level are defined in ASTM F1637, Standard Practice for Safe Walking Surfaces. The standard permits abrupt changes in elevation of up to 1/4 inch, or up to 1/2 inch if the edge of the surface is sloped or beveled. Similar requirements are also provided in ANSI A117.1 Accessible and Usable Buildings and Facilities and the 2010 ADA Standards for Accessible Design. Local jurisdictions may have different or more detailed requirements. For example, the New York City Building Code defines permissible depths and widths for sidewalk cracks and the New York City Department of Transportation defines limits for acceptable sidewalk slopes. The US Department of Housing and Urban Development provides a less stringent requirement, permitting abrupt changes in elevation of up to ¾-inch. Forensic experts familiar with the local codes and standards can provide guidance as to the applicable requirements and whether the conditions could be considered hazardous.

Geometric requirements for handrails, guardrails, ramps, and stairs are defined in Chapter 10 of the International Building Code (IBC), the building code adopted by most jurisdictions in the US. Requirements for stairs come up most often in trip and fall evaluations. Again, similar requirements are also published in ANSI 117.1 and the ADA Standards for Accessible Design. Stair risers must be between 4 inches and 7 inches high, and critically for preventing trips, the riser dimensions must not vary by more than 3/8 inch over a given flight of stairs. A person will naturally lift their foot only as much as needed to clear the previous step in a flight of stairs—larger riser heights later in a flight of stairs can be particularly hazardous.

Not every as-built condition fits neatly within the parameters defined by the building code.  For example, the authors worked on a trip and fall case where a parking lot curb had a different riser height than an adjacent stair. Opposing experts had differing opinions as to whether the curb was part of the stair and was therefore subject to the building code geometric requirements.

The codes and reference standards are generally not retroactive; design professionals are only responsible for meeting the requirements in effect at the time of design and in most cases, building owners do not need to make repairs to address code changes. On several occasions, the authors have seen other experts incorrectly citing the current code instead of the version that was in effect at the time of the accident.

Slip Hazards

Slip accidents occur when a person falls due to a lack of friction between the walking surface and the person’s footwear. The standard ANSI A1264.2, Provision of Slip Resistance on Walking/Working Surfaces, provides some guidance on what could be considered a slip hazard. The authors “suggest a slip resistance guideline of 0.5 for walking surfaces.” A slip resistance (also referred to as a coefficient of friction) is the ratio between the horizontal force required to cause a slip and the vertical force acting on the surface, due to the person’s weight. The lower the slip resistance, the more likely a slip will occur. Slip resistance can be measured in the field using a digital tribometer, a shoebox-size piece of equipment that crawls along the floor using internal rubber pads to determine the coefficient of friction.

Another common method for evaluating slip hazards is to use a pendulum tester per ASTM E303, Standard Test Method for Measuring Surface Frictional Properties Using the British Pendulum Tester. The device features a pad with shoe sole simulating rubber on the end of a swinging pendulum. The pendulum is dropped from a standardized height and contacts the ground before rebounding on the other side. For slippery floors, the pendulum will rebound higher, and give lower readings, or Pendulum Test Value (PTV) values. Most flooring manufacturers aim to develop products with a PTV of at least 36 to prevent slips.

The evaluation of slip hazards is not as simple as comparing the measured slip resistance to those established in guidelines. The minimum PTV values of 36 and slip resistance of 0.5 are not codified requirements. The ANSI standard that recommends a slip resistance of 0.5 also notes that “floors that do not meet this guideline are not necessarily hazardous.” The standard also notes that slips can occur on surfaces with a slip resistance exceeding the 0.5 guideline value. Many factors can contribute to a slip, including the type of footwear, whether the surface was wet, whether the person was carrying something, as well as human factors such as the attentiveness and gait of the person. As such, evaluation of responsibility for slip and fall hazards often requires experience and expertise to identify the root cause of the accident.

As an example, the authors once investigated a slip and fall accident that occurred at a painted curb outside a shopping center. Our review of available documents and field evaluation found that the contractor that painted the curb did not use an anti-slip aggregate in the paint that was recommended by the paint manufacturer. Defendants in the case, including the owner, architect, and property manager, were able to identify this error by the contractor as the root cause of the fall, thereby reducing their liability. Measurement and analysis of the actual slip resistance of the curb was not required.

Root Cause Analysis

An attorney defending a slip/trip and fall claim may consider the following arguments:

1. The plaintiff is solely responsible for the accident. Falls can and do sometimes occur absent any real hazard. Engineering experts can help review the codes and standards that define hazardous conditions, and where appropriate, offer the expert opinion that the premise was reasonably safe.
2. The plaintiff was not harmed. A plaintiff’s claims of how they fell can sometimes be inconsistent with the existing conditions. Alternatively, the claimed injuries could be overstated or unrelated to the fall. Medical experts can evaluate the appropriateness of medical claims and biomechanical experts can review the mechanics of a fall to evaluate consistency with the plaintiff’s claims. Falling often results in trauma to the hands and arms from the reflex to catch oneself. Falling forward, associated with a trip, can cause trauma and injury to knees and other anterior regions. Slips typically cause a fall backward and can cause injury to the back, neck, and head. Biomechanical experts can combine information from the accident location and extent of injuries with the physics of the fall – including a person’s weight, center of mass, and velocity – to determine if reported injuries are consistent with the reported incident. Animations of falls can be created for use at mediation or trial.
3. The defendant was not responsible for the condition that caused the accident. When a hazard at the accident site is found to exist, the defendants will try to identify which of the other defendants may be responsible (or at least partially responsible) for the condition. This type of defense usually requires consultation with engineering or architectural experts.

Design Defects: Similar to construction litigation cases, design professionals (most typically architects, structural engineers, and civil engineers for slip, trip and fall cases) can be found responsible if their work did not meet the standard of care. The standard of care is often defined as the care that other design professionals practicing in the same area would exercise in similar circumstances. Examples of failures to meet the standard of care could include the design and specification of stairs, ramps, railings, curbs, or flooring that did not meet building code requirements. Omitting key details from the contract documents (for example, letting the contractor determine the required geometry of a stair) or not providing adequate oversight/review during construction can also be grounds for a claim. Such a claim typically requires review by a corresponding professional who can opine that the design professional did or did not meet the standard of care.

Construction Errors: Contractors can be found responsible for accidents if the as-built conditions do not match what was called for on the design documents, the approved shop drawings, or the manufacturer’s installation requirements. Again, a detailed review of the project documents and comparison to the as-built conditions is required to support such a position.

Lack of Maintenance: Accidents can also occur when the premises are not adequately maintained. Examples include failure to remove ice or other slippery conditions from a walking surface, or failure to repair a stair that has settled and become uneven. In general, the property owner and their property manager are responsible for maintaining the premises in a state free from hazardous conditions, but owners are not responsible for identifying and fixing latent conditions caused by construction errors or design defects. Specific requirements for inspection and repair are defined in the International Property Maintenance Code. Other standards, such as those published by the National Floor Safety Institute, define common practices for identifying and eliminating slip and trip hazards. Local jurisdictions may have additional maintenance requirements within the administrative portion of the building code. Sometimes it may not be obvious whether a hazardous condition arose due to lack of maintenance or due to poor design. For example, the deterioration of a sidewalk could be due to poor maintenance or due to a contractor’s use of poor-quality concrete. Other times, a hazard may have existed, but the owner or property may not have had reasonable time to identify and remedy the condition before the accident occurred.

In most situations, the root cause of an accident will not fit neatly into one of these three categories. Attorneys with a basic understanding of the industry standards and technical requirements outlined in this article can quickly pick up on the key issues—and identify when a forensic engineer or architect may be required to provide expert support.