Sidewalk & Walkway Trip Hazards Expert Article

Trips and falls occur when unanticipated variations in walking surfaces interrupt the motions of a pedestrian’s foot. Studies of pedestrian falls have identified that small changes in elevation are particularly dangerous because of the low probability that pedestrians will reliably detect them.

In this article, architect and premises safety expert, Thomas Lodge discusses hazards associated with abrupt changes in walkways such as interior floors and walkway surfaces such as sidewalks and short flight stairs.

Sidewalk & Walkway Trip Hazards

Harvey Cohen and Jake Pauls, in their article “Warnings and Markings for Stairways and Pedestrian Terrain,” have identified that trips are caused by unexpected impediments in a level walking surface and unexpected change in level, and describes:

“Trips and resultant stumbles most often occur during the swing phase of the stride, when the forward motion of the foot is halted unexpectedly. This can be a brief impediment that usually causes a slight, recoverable stumble (where the foot quickly manages to come free), or a longer impediment, where the toe or heel actually becomes caught and a more serious fall results. In both cases, the fall and stumble are almost always forward in motion, and can result in injuries to the hands, elbows, shoulders, head, or knees.”¹

Perception and Visibility of Walkway Trip Hazards

Visual cues in the architecture, site planning, and design of interior and exterior spaces facilitate safe use and enjoyment of the premises by its users. Lack of clarity in visual cues, or any defect in their interpretation or comprehension of the environment, can reduce a person’s ability to understand or to safely navigate the environment; and may cause a hazard to become a dangerous condition. A hazard is a physical condition that may cause harm. A condition becomes dangerous with the likelihood or probability of the hazard being encountered in a manner to cause harm.

When a pedestrian encounters an unexpected obstacle or impediment and does not perceive it in their route of travel, trips and falls occur. An obstacle is unexpected if it is unmarked or provides no other visual cue to alert the pedestrian. The visual field of a walking person is moving and dynamically changing, with only a small part of that field being attended to. Obstacles that fall outside of this small field of view are not perceived unless they are conspicuous and unobstructed. If impediments were marked or expected, the pedestrian likely would perceive the existence of the impediment and take appropriate action to either avoid or safely traverse the condition.

Pedestrians typically scan ahead in the direction of their travel, not directly down in front of their feet. Low elements in the path of travel are not readily identified and are frequent causes of falls resulting in injury. Pedestrians are not likely to see and avoid inconspicuous walkway and sidewalk hazards at or near ground level. If the first identification of a hazard comes when there is an interruption of the gait and loss of balance, a trip and fall may result. Abrupt vertical edges as low as 3/8” have been identified as walkway hazards, and are the cause of falls.

Changes in Walkway Elevation

Walking is easiest and safest on stable, planar, flush, and non-slippery surfaces. Conditions that increase the difficulty of negotiating changes in level while walking, can lead to falls and serious injuries. Floors, patios, sidewalks, parking lots, and pathways are all walking surfaces that must be constructed and maintained without tripping hazards. Standards for safe walkways require that walk surfaces be designed, constructed, and maintained to be safe and free from hazards.

Some examples of sidewalks distresses/deficiencies requiring correction are:

• Heaved slabs, step separation, and paver irregularities. A vertical displacement at any point on the walkway could cause pedestrians to trip.
• Spalled areas and cracked concrete. Fragments of concrete or asphalt separated from the surrounding paving and holes and rough spots could cause pedestrians to trip.
• Settled areas that trap water. Sidewalk segments with depressions, reverse cross slopes, or other indentations may create depressions that trap silt and water on the sidewalk and may reduce the slip resistance of the walking or create tripping hazards.
• Tree root damage. Roots from trees growing in adjacent landscaping that cause the walkway surface to buckle and crack could cause pedestrians to trip.

Hazards of Short Flight Stairs and Single Step Transitions

Single-riser stairs should be avoided where possible. In situations where a short flight stair or single step transition exists or cannot be avoided, obvious visual cues shall be provided to facilitate improved step identification. Handrails, delineated nosing edges, tactile cues, warning signs, contrast in surface colors, and accent lighting are examples of some appropriate warning cues.

Conspicuity of Walkway Hazards

Since pedestrians will assume that walkways do not have hazards, property owners must either eliminate hazards, guard hazards from being encountered by unsuspecting pedestrians, or apply visual cues or other such warnings that make hazards reasonably conspicuous so that their existence may be identified before they are encountered in a manner to cause harm.

Nationally recognized standards for providing safe facilities address visual performance and identify that conspicuity (or the likelihood of a person to identify a potential walkway hazard) is a function of size, contrast, and brightness. The relationship between these critical variables will determine whether a person will reliably identify or recognize an object.

Abrupt changes in walkway elevation that contrast poorly with the surrounding walkway material make it likely to blend in visually with the surrounding environment. An abrupt change in walkway elevation’s ability to be readily identified as a hazard may be improved by applying adequate warnings such as delineated nosing edges, tactile cues, warning signs, or contrast in surface colors. Such warnings may assist pedestrians to identify a dangerous condition that could cause a fall and injury; however, such cues or warnings are not a substitute nor do they negate the need for safe design or construction.

Walkway and Sidewalk Maintenance

For property owners, the standard of care for walkways and sidewalks includes maintaining safe premises and ensuring the protection of pedestrian health, safety, and welfare. The property owner is responsible for ensuring that reasonable periodic inspections are conducted to identify hazards, and correcting those hazards in a prompt manner. When dangerous conditions exist, reasonable efforts should be made to remove them or prevent them from being encountered in a manner that could cause harm.

For nearly 30 years, ASTM F1637 - Standard Practice for Safe Walking Surfaces has been a nationally published and recognized consensus standard that provides minimum maintenance requirements for safe walkways, including exterior walkways and sidewalks. It requires:

• Exterior walkways shall be maintained so as to provide safe walking conditions.
• Exterior walkway conditions that may be considered substandard and in need of repair include conditions in which the pavement is broken, depressed, raised, undermined, slippery, uneven, or cracked to the extent that pieces may be readily removed.
• Exterior walkways shall be repaired or replaced where there is an abrupt variation in elevation between surfaces.

Readily available resources from organizations such as the Building Owners and Managers’ Association (BOMA) and the National Safety Council (NSC) offer property-owners further information and guidance on inspecting and maintaining safe pedestrian walkways.

If a hazardous impediment in a level walking surface is located in a premises’ means of egress, the condition may also be subject to local building and fire codes. Building and fire codes require that floors, walkways, and applicable sidewalks and parking lots in a means of egress be reasonably and continuously maintained free from obstructions or impediments to full instant use in the case of fire or other emergency.

Sidewalk Expert Witness Investigations

The Premises Safety experts at Robson Forensic are frequently retained to investigate cases involving slips, trips, and falls as they relate to floors and walkway surfaces, sidewalks, short flight stairs, gratings, wheel stops, and speed bumps, and other architectural features. Our experts are well versed in the standards relevant to pedestrian safety as well as industry standards governing retail, residential, and commercial premises.

For more information, submit an inquiry or contact the author of this article.

^{1. Handbook of Warnings, Edited by Michael S. Wogalter, 2006, Lawrence Erlbaum Associates (Mahwah, NJ), p. 712↩}

Featured Expert

Thomas J. Lodge, AIA, NCARB

Architecture, Construction & Premises Safety Expert

Thomas Lodge is a versatile and accomplished registered Architect with over 30 years of broad professional experience in design, construction detailing, and construction administration for a… read more.