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72 Wayfinding and Signing Guidelines for Airport Terminals and Landside should be used as a starting point; final selection should be based on what colors create the best contrast for text and background colors. Select colors that will read well in all lighting conditions. 4.5 Sign Locations, Structures, Materials, and Safety 4.5.1 Sign Locations With the exception of roadway and terminal signing, more guidance is available for signing in parking garages than for other areas at airports. Guidance in such documents includes placement of signs, types of signs, signs for pedestrians versus vehicles, and informational needs for various location with the parking facility31,32. Because every parking facility has a unique location, archi- tecture, configuration, and geometry, it is difficult to prepare generic parking signing plans and recommendations. 4.5.2 Illumination Options Because the ambient light levels along roadways in most major airports can vary (from termi- nal buildings, roadways, and landscaping) it may be necessary to use external or internal illumi- nation to provide adequate nighttime visibility for parking signs so that they compete equally. At smaller airports or on the outlying areas of larger airports, with lower ambient light levels, high quality retroreflective materials may provide adequate visibilities. Nighttime testing on-site will be required to make these determinations. 4.5.2.1 Retroreflection Retroreflective sign sheeting materials return light from vehicle headlamps to the driver's eyes. Retroreflection is achieved either through microscopic glass beads with a thin metallic backing or through microprisms in a thin polycarbonate film. These materials vary in the daytime color appearance and in their nighttime brightness and efficiency with which they reflect the vehicle headlamps. In some airports, the geometry of a parking facility is such that considerable care must be taken by the designer in sign location and orientation to ensure that vehicle headlamps will adequately illuminate the sign along the necessary driving sections. In order to get the maximum benefit from retroreflective sheeting in a garage, the sign panels should be angled towards the driver (typically 5 to 8 degrees). The use of high quality retroreflective sheeting in place of external illumination may also help airports reduce electricity and maintenance costs and reach sustainability goals. 4.5.2.2 External Illumination (Ambient Light) External illumination of parking signs within a parking garage can often be achieved through the ambient garage lighting. If ambient light is used, ensure the signs are located near existing light sources as much as possible. If additional lighting is needed for signing, it is rec- ommended that internally illuminated signs be chosen over externally illuminated signs in the garage environments. This is to reduce the amount of electrical infrastructure required to sup- port external illumination and to eliminate head clearance issues when ceiling heights are already reduced. 4.5.2.3 Internal Illumination Internally illuminated signs can be designed to provide sign recognition and legibility dis- tances comparable to those of externally illuminated. Proper materials and design must be used for the specific viewing angles present for a specific sign location. Candidate sign materials should

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Parking 73 be viewed in daylight and dusk conditions to ensure that there is adequate contrast when the sign is not lit. 4.5.3 Sign Structures The following are the types of general sign mounting frequently found in parking facilities: Overhead Suspended--signs that are suspended from the ceiling using a cable or break-away fastening system. Check wind load requirements. Soffit Mount--signs that are located on an architectural soffit or wall, and mounted with the back of the sign to the soffit or wall using a mechanical fastening system. Ceiling Mount--signs that are located flush to the ceiling and mounted with the top of the sign to the ceiling using a mechanical fastening system. Flag Mount--signs that are mounted perpendicular to the attachment surface, usually on a wall and/or soffit, and attached using a mechanical fastening system. Post Mount--signs that are mounted directionally to a ground-mounted single or double post structure using a mechanical fastening system. Wall Mount--signs that are mounted with the back of the sign to the wall using a mechani- cal fastening system. Freestanding--signs that have their bases mounted directly to the ground/finished floor using a mechanical fastening system. Light Pole Mount--signs that are mounted directly on the existing light pole structure. Overhead Roadway--signs that are mounted directly above the lane of traffic to a ground- mounted structure using a mechanical fastening system. Appendix B contains detailed graphics illustrations with recommended clearances for various sign types and locations. 4.5.4 Pedestrian Safety Considerations Specific research to analyze pedestrian and vehicle interactions within parking areas at airports has not been compiled, but research has been conducted to analyze and make safety recommen- dations for pedestrians at locations with high volumes of vehicles and/or pedestrians at other locations33. Once an engineering study is completed, recommended treatments for safety improve- ments can be determined. These treatments fall into one of the four categories described in Figure 4.22. Treatment Description Category Crosswalk This category encompasses standard crosswalk markings and pedestrian crossing signs, as opposed to unmarked crossings. Enhanced This category includes those devices that enhance the visibility of the crossing location and pedestrians waiting to cross. Warning signs, markings, or beacons in this category are present or active at the crossing location at all times. Active Also called "active when present," this category includes those devices designed to display a warning only when pedestrians are present or crossing the street. Red This category includes those devices that display a circular red indication (signal or beacon) to motorists at the pedestrian location. Figure 4.22. Table of possible treatments to enhance pedestrian safety.