In this short article, the highway engineering experts at Robson Forensic provide an overview of parking lot design. The graphic provided highlights some of the common design elements we encounter…
In this article, civil engineer, Gordon Meth, P.E. discusses the prevalence of pedestrian v. vehicle strikes in parking lots. He examines the scope of the problem as well as parking lot design elements that affect pedestrian safety.
Each year the experts at Robson Forensic investigate hundreds of vehicle crashes, slips/trips, and assaults that occur in parking lots. The experts who investigate each matter vary based on the issues at hand. Please contact us to be put in touch with an appropriate expert for your case.
Data from professional organizations, as well as experience from our own forensic casework supports the fact that pedestrians being struck by vehicles in parking lots is a remarkably common occurrence. Within the recent informational report by the Institute of Transportation Engineers (ITE) entitled “Pedestrian and Bicycle Safety in Parking Facilities” (2017)1, 480 vehicle-pedestrian crashes occurred in parking facilities over a 3-year period in 45 New Jersey municipalities. These 480 crashes represented 17 percent of all vehicle-pedestrian crashes over that period in those municipalities. For perspective on the scope of the problem, it is worth noting there are over 550 municipalities in the State of New Jersey.
The aforementioned ITE informational report found that the incidence rate of vehicle-pedestrian crashes in parking facilities varies substantially by type of land use that the parking facility accommodates, the design of the facility, and the general maintenance and upkeep of the facility.
Understanding Components of Parking Facilities
Surface parking lots can be divided into a few separate components – parking aisles, Building Frontage Roads (BFR), circulation road or ring road, and extended driveway. Except in sites controlled with gate access, all of these components, except parking aisles, fall under the definition of Site Roadways Open to Public Travel (SROPT). In accordance with a 2007 Federal Rule, these components of sites are required to be in substantial conformance to the Manual on Uniform Traffic Control Devices (MUTCD) with respect to traffic controls, including signage and pavement markings.
Overall Parking Lot Crash Patterns
Based on the aforementioned ITE study of 480 vehicle-pedestrian crashes in parking facilities, 73 percent occurred in retail land uses. Shopping centers had the highest number of crashes, followed closely by big box retailers and grocery stores. In fact, these three uses accounted for half of all vehicle-pedestrian crashes in parking facilities. In contrast, offices accounted for only two (2) percent of vehicle-pedestrian crashes in parking facilities.
The worst time for vehicle-pedestrian crashes is midday, between 12 pm and 4 pm. Nearly 40 percent of all 480 vehicle-pedestrian crashes in parking facilities within the study occurred during that timeframe. The second-worst time period was 4 pm to 8 pm, when 30 percent of the crashes occurred. Over 70 percent occurred in daylight.
Over 50 percent of the studied crashes occur in parking aisles, and over 20 percent along building frontage roads. Vehicles backing was a factor in a third of these crashes, and vehicles making left turns was a factor in nearly 15 percent.
Best Practices in Parking Lot Design to Reduce Pedestrian Fatalities
Based on a survey of designers of parking facilities, bicycle and pedestrian safety planners, and owner/operators of parking facilities, the following are the most important considerations for pedestrian safety:
Other key findings of the report are as follows:
Accessibility
All facilities are required to be compliant with the Americans with Disability Act Accessibility Guidelines (ADAAG)2, not just for pedestrian access from vehicles but for pedestrian access to the site from the public right of way. This means having parking spaces most convenient to the facility being accessible, and there must be an accessible route from these spaces to the building. In this context, accessible parking spaces have specific size and marking requirements, and need to be flat (i.e. 2 percent or less) in every direction. The accessible route must have no steps, maintain 36 inches clear width, have no more than 2 percent cross slope, and any grades greater than 5 percent require handrails. Ramps with handrails must be no more than 1 foot rise for 12 feet horizontal, and must have landings every 2.5 feet in rise. ADAAG requirements need to be considered during renovations and when positioning outdoor displays and cart racks. Another requirement of ADAAG that is often overlooked in parking lots is the requirement to provide an accessible route to public transit stops, public streets, or sidewalks.
Lighting
Although good lighting was indicated as critical to bicycle and pedestrian safety in the survey from the previously cited ITE source1, lighting was rarely found to be a factor in pedestrian and bicycle crashes in the same source. Lighting is often highly regulated by local zoning regulations, in an effort to reduce impact on neighbors and sky glow impacts. An important consideration for parking facility lighting is that it must not just provide sufficient light for seeing and security, it is important to manage the uniformity of lighting as well (i.e. the differential between the most lighted and least lighted areas), as bright spots can make adjacent lesser lit spots be perceived as darker than they actually are by the human eye. Towards that end, it is important to consider ambient lighting in the area – most lighting plans are designed in isolation. For instance, a lighted area located near a brightly lit gas station may, by comparison, be perceived to be darker than it actually is.
Given the amount of vehicle-pedestrian crashes in high turnover parking lots, such as supermarkets, big box retailers, and other retail establishments, pedestrians must be afforded reasonable protections from impacts with vehicles. Key areas of concern are building frontage roads and parking aisles. The best approach is to design away the hazards by reducing traffic volume using the building frontage road and to reduce vehicle speeds throughout the facility. Well-marked and signed pedestrian crossings are also important, and all signs and pavement markings should be in conformance to the Manual on Uniform Traffic Control Devices. Pedestrians walking in parking aisles are inevitable, as are backing vehicles. Narrower aisles are a particular hazard, as they limit the amount of room pedestrians have to avoid backing vehicles.
The experts involved in parking lot investigations vary from case to case, but often include civil engineers, architects, premises security professionals, or retail operations experts. Our experts investigate hundreds of parking lot incidents each year and it is likely we are familiar with the issues relevant to your case.
Call or submit an inquiry to tell us about your case.
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