Previously, our premises safety experts addressed parking lot design and the use of wheel stops as they relate to slip, trip, and fall injuries, and pedestrian strikes. This article discusses the surface of the typical parking lot, common forms of asphalt deterioration, and the resulting hazards that can be present.
Parking Lot Surface Hazards - Expert Article
Parking lots, paved storage yards, and street crossings are considered exterior walkways if they are reasonably foreseeable pedestrian paths. A significant percentage of exterior walkways have surfaces that are made of asphalt concrete which is susceptible to disintegration. If not identified and repaired, defects in asphalt surfaces can present a risk to public safety. This article will focus on parking lots, but the information also applies to other asphalt paved walking surfaces.
STANDARD OF CARE
Model codes and other established standards exist to protect public health, safety and general welfare. The National Safety Council states that pedestrian safety must be considered in parking lots, and there are applicable codes intended to protect pedestrians using walking surfaces to and from parked cars. With regards to asphalt defects located in walking surfaces of parking lots, industry standards require;
- Maintaining exterior walkways to provide safe walking conditions.
- Providing walkways that are stable, planar, flush and even.
- Addressing any sudden change in elevation measuring ¼” or more.
Hazards created by deterioration include potholes, changes in elevations, and cracks in the walking surfaces due to uneven settling of the ground. The rate and extent of deterioration can be affected by wear caused by heavy vehicles, and the effects of weather.
Bituminous concrete, commonly called asphalt, blacktop, or asphalt pavement, is a composite material used to surface roads and parking lots. It consists of mineral aggregate (stone) bound together with asphalt (asphalt cement), laid in layers, and compacted. The pavement is placed atop a compacted base of aggregate on subsoil. Common conditions of asphalt deterioration include:
- Rutting – Surface deformation of the pavement caused by consolidated or lateral movement of the material due to traffic load. Pavement uplift may occur along the sides of the rut.
- Shoving – Surface deformation when traffic pushes against the pavement and produces a short, abrupt wave in the pavement surface.
- Raveling – Surface deformation caused by the wearing away of the pavement surface due to loss of asphalt or tar binder and dislodged aggregate. Raveling may be caused by certain types of traffic, for example, tracked or aggressively treaded vehicles. Softening of the surface and dislodging of the aggregates due to oil spillage also are included under raveling.
Conditions such as rutting, shoving, or raveling can result in uneven and hazardous walking surfaces and should be addressed to prevent pedestrian injuries. As we discuss in our article on Property Maintenance, premises safety is addressed through two primary methods: preventive maintenance, and unplanned maintenance.
DAMAGE FROM VEHICLE FLUIDS
Asphalt cement is a petroleum product that can be dissolved by other petroleum-derived products such as gasoline and car oil. This form of damage can be observed in parking lots where dripping oil from leaking automobile engines has eroded the asphalt in the center of parking stalls. Where asphalt is exposed to the imposed loads of vehicular traffic, it flexes and will deteriorate faster if the sub-base below the asphalt surface was not prepared correctly. It becomes progressively more porous, allowing moisture and chemicals to penetrate into and underneath the pavement leading to fatigue (alligator) cracking; interconnected cracks that resemble the skin of an alligator. The pavement eventually breaks up into small pieces that become dislodged over time.
When enough small pieces are dislodged, bowl-shaped depressions begin to form potholes. They are usually less than 30” wide and generally have sharp edges and vertical sides near the top of the hole. These vertical sides in most instances are greater than those changes in elevation allowed by standards for safe walkways. Turned ankles, missteps, trips, and falls may be reduced through proper preventative maintenance.
The entity responsible for managing the property is expected to maintain the asphalt surface in a safe condition for pedestrian safety. Regularly scheduled maintenance prevents deterioration of the asphalt binder and preserves the integrity of the surface by halting cracking before it starts. In order to properly repair deteriorated asphalt conditions, they must first be identified. Proper inspection and maintenance are required to minimize the chance of injury from trips and falls.
Due to the rapid deterioration of asphalt once it starts to fail, it is important that inspections are made routinely. Cracks in asphalt are the precursor to potholes and should be mitigated by property managers before they become worse. This process is greatly accelerated in areas that have snow, ice, and the associated anti/de-icing and snow removal procedures.
Periodic inspections by maintenance staff are useful to identify hazards like potholes, changes in elevation, cracks, and any visible signs of distress. Due to asphalts unique characteristics, deterioration can progress rapidly depending on the environmental conditions.
Pavement disintegration must be addressed before too much of the pavement surface has been lost. Best practices for preventative maintenance include:
- Seasonal inspection and cleaning of drainage systems.
- In localized areas where extensive fuel spillage is likely, it may be advisable to seal the pavement with a commercially-available proprietary sealer that is impervious to petroleum solvents.
- Ongoing inspection of parking lots to determine defects before they become dangerous.
Once distress has been identified, the property manager should have an action plan in place to provide the necessary level of remediation based on the severity of deterioration and risk to public safety. Maintenance practices involving infrastructure are categorized in three main groups: temporary; short term measures; and longer term measures lasting many years (in some situations even over ten years). Temporary measures are made just to reduce hazards and last less than a year. Short term measures typically last one to five years and are intended to extend the life of the walkway surface until it is replaced. Long term measures include replacement. When walkway replacement requires more than simple maintenance, the repairs could require improvements and updates under the American with Disabilities Act (ADA).
Pavement line striping must also be maintained and repainted periodically, as it is essential to directing pedestrian and vehicle traffic, establishing crosswalk areas, parking spot boundaries, and fire zones. The removal of pavement markings should be executed in a way which allows motorists and pedestrians to clearly see their intended path of travel without being confused or misled. For more on pavement marking removal, read our article on the subject.
PARKING LOT & WALKWAY SAFETY
Any surface that is a reasonably foreseeable pedestrian path shall be maintained so as to provide safe walking conditions. Parking lots and other asphalt surfaces are walking surfaces and are known to become hazardous over time if they are not maintained. Establishing and following a program of inspections and maintenance is a major part of protecting the health and safety of pedestrians using an asphalt walking surface.
PARKING LOT INJURY INVESTIGATIONS
This article was authored by Scott Klimek with input from other experts in our Premises Safety practice group. The Premises Safety experts at Robson Forensic are frequently retained to investigate cases involving slips, trips, and falls as they relate to parking lots, sidewalks, and other architectural features. Our experts are conversant in the standards relevant to pedestrian safety and industry standards governing retail, residential, and commercial premises.
For more information submit an inquiry, or contact your local Robson Forensic office.
Architecture, Construction & Premises Safety Expert
Scott Klimek is a Licensed Architect with over 20 years of experience in building design, document preparation, code compliance, and construction administration procedures. He has a diversified background that includes all phases of project design, construction, and occupancy, from initial conception through final acceptance, use and maintenance, and demolition. Scott is experienced in the design and documentation of large scale commercial and residential projects. These have included highly specialized projects such as healthcare, justice and corrections facilities, educational institutions, arts and entertainment facilities, and sports facilities. He is also well versed in issues for special users, including Barrier-Free standards and Americans with Disabilities Act (ADA) guidelines.