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37 Parking garages are considered critical security locations with a high potential for crime. There are a number of reasons for this: parking areas are usually public, they can be large and vacant, and they often have many corners, beams, parked vehicles, and other dark hiding places. Because parking garages have foot and vehicle traffic, it is easy for a loitering criminal to blend in with other pedestrians or drivers. Parking garages, in particular, have much less natural sur- veillance compared to parking lots because they are partially or fully enclosed (Jeremy, 1996). A number of case studies have shown that providing proper lighting can reduce car break- ins, robberies, vandalism, and burglaries. Crime Prevention Through Environmental Design (CPTED) can be adopted to enhance the security of the parking garages. CPTED designs con- sider many parking garage features, like natural surveillance, stair towers, elevators, access con- trol, signs and graphics, and restrooms. Among CPTED considerations, lighting is the most strongly recommended passive security feature. With respect to lighting, CPTED shares many themes with the RP-20 guidelines, but CPTED goes beyond the RP-20 to recommend the fol- lowing (Jeremy, 1996): ⢠Illuminance: Both horizontal and vertical illuminance need to be carefully considered. While horizontal illuminance provides lighting on horizontal surfaces, which is useful for seeing the ground, the vertical illuminance provides lighting on vertical objects such as signs and keyholes and for facial recognition. ⢠Uniformity: The maximum or average illuminance divided by the minimum illuminance gives the uniformity ratio. The uniformity should be assessed not only for driving aisles but also for the edge of parking stalls to avoid transitions between light and dark areas. ⢠Glare: Glare is a general problem, but it is most critical to senior citizens and individuals with impaired vision. In glare conditions, it is difficult to clearly perceive objects because of the lack of contrast between the object and its background. Lights should be installed over parked vehicles rather than in the center of the aisle. In one-way routes, the lights can be installed near beams to provide shielding for glare reduction. Some light fixtures have built-in shields for the same purpose. ⢠Industry standards: The IESNA and the Parking Consultants Council (PCC) of the National Parking Association (NPA) provide some guidelines, as shown in Table 12. ⢠Level of service: Parking facility owners, city officials, and architects are familiar with the term level of service (LOS). In parking garage lighting design LOS is based on illuminance level and has different grades (e.g., grade A: superior design, B: above average, C: average, and D: below average but still passing) as shown in Table 13. ⢠Concrete stain: General brightness and uniformity can be enhanced by staining concrete, which is a cost-effective technique. It has the potential to even improve the lighting by one LOS. Paint can provide similar brightness, but maintenance cost is much higher. Staining of concrete may last more than 10 years. C H A P T E R 6 General Safety
38 Airport Parking Garage Lighting Solutions Area Horizontal Illumination (foot candles) NPA IESNA Covered parking areas - 5 (at night) General parking areas 6 5 Minimum at bumper walls 2 1.25 Ramps and corners - 10 Vehicle entrance 40 50 Vehicle exit 20 - Stairwells, exit lobbies* 20 10 (low activity area) 15 (medium activity area) 20 (high activity area) Roof and surface parking* - 5 (vertical illuminance at 6 ft above pavement) General parking areas 2 0.8 (low activity area) 2.4 (medium activity area) 3.6 (high activity area) Vehicle ramps - 0.5 (low activity area) 1.0 (medium activity area) 2.0 (high activity area) *Average foot candles converted from minimums using 4:1 uniformity ratio Source: VTTI compiled from Jeremy 1996 data Table 12. Industry standards for illumination for security. Maintained Illumination Levels per Level of Service (foot candles) A B C D Average Horizontal Illuminance at Pavement Covered parking areas 10 8-9 6-7 5 Roof and surface parking areas 3 2.5 2 1 Stairwells, elevator lobbies 20 16-18 12-14 10 Uniformity ratio (avg:min) 3:1 3:1 4:1 4:1 Uniformity ratio (max:min) 8:1 8:1 10:1 10:1 Minimum Vertical Illuminance at 42 in. Above Pavement Covered parking areas 1.6 1.4 1.2 1 Roof and surface parking areas 0.38 0.31 0.25 0.13 Stairwells, elevator lobbies 2.5 2.1 1.6 1.3 Source: VTTI compiled from Jeremy 1996 data Table 13. Recommended horizontal and vertical illuminance levels for security.
General Safety 39 CPTED can also reduce some costs associated with hiring security personnel. Even though including CPTED in the parking design process is relatively easy and inexpensive, most property owners and architects are not aware of its basic principles. As a result, some possibly more- expensive active security strategies, such as closed circuit television (CCTV) systems and security patrols, become necessary in poorly designed buildings (Jeremy, 1996). Another study, essentially a literature review on lighting and security, examines nighttime lighting to find out whether it has an impact on crime or the fear of crime. No sufficient evi- dence was found to support a relationship between nighttime lighting and crime itself. However, a significant relationship was demonstrated to exist between the lighting and the fear of the crime (Heschong Mahone Group, 2008). There are mixed results on whether lighting can reduce crime, but it does affect the comfort of airport garage users. Recommendation: When designing airport garage lighting, consider adopting CPTED recommendations.
