Applications of Illuminated, Active, In-Pavement Marker Systems (2008) / Chapter Skim
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Pages 8-17
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From page 8... ...
Although laser beams provided sharply visible lines in fog, visibility is significantly affected by the amount of ambient lighting and the luminous intensity and viewing angle of the laser. Use of this technology also requires a mechanism to prevent road users from viewing the laser beams directly.
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From page 9... ...
IRWL equipment enclosures shall contain a power supply, controller unit compatible with IRWL operation, flasher unit, circuit breakers, terminal blocks, wiring, and electrical components for operation of the IRWL system. Installation Installation of IPM systems generally includes placement of the electrical cable and conduit to power the system and placement of the markers.
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From page 10... ...
Historically, a broader array of methods has been used to provide passive activation of IPM systems including: • In-ground sensors, • Motion sensors, • Visual image video detection systems (VIVDS) , • In-pavement loop detectors, • Integration with traffic control devices, and • Road-weather information systems (RWIS)
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From page 11... ...
Chase sequencing has been used to maintain or reduce vehicle speeds in fog-prone areas and to reduce vehicle speeds on exit ramps. Other potential applications for chase sequencing include horizontal curves, tunnels, merge areas, or construction work zones.
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From page 12... ...
Similarly, a highway traffic signal alternately stops or permits traffic to proceed depending on vehicle or pedestrian presence. Other types of IPM system applications, such as horizontal curve or adverse weather warning, multiple-turn lane or tunnel guidance, or vehicle and truck inspection point illumination may be more appropriately categorized as pavement marking, delineator, or illumination source, respectively.
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From page 13... ...
Applicable MUTCD Standards and Guidance Warning School zones 7B.11 School Speed Lim it Assembly 7C.03 Crosswalk Markings Construction zones 6D.03 Worker Safety Considerations 6F.73 Raised Pavem ent Markers Highway-rail crossings 8B.06 Turn Restrictions During Preem ption 8B.21 Stop Lines 10C.23 Pavem ent Markings Horizontal curves 3D.02 Delineator Design 3D.03 Delineator Application 5E.03 Edge Line Markings Adverse weather Guidance Multiple-turn lanes 3D.02 Delineator Design 3D.03 Delineator Application Merge locations 3D.02 Delineator Design 3D.03 Delineator Application Tunnels 3D.02 Delineator Design 3D.03 Delineator Application 5E.04 Delineators Regulation Intersection stop bars 8B.21 Stop Lines Left-turn restrictions 8B.06 Turn Restrictions During Preem ption Illumination Vehicle/truck inspection points None Environmentally sensitive areas None TABLE 1 APPLICABLE MUTCD STANDARDS AND GUIDANCE
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From page 14... ...
2005) : • Light sources should have a lifespan equaling at least that of conventional pavement marking equipment, and preferably that of road surfaces; "only LED technology currently meets this criteria." • The protective housing should be composed of highquality synthetic material, which can be milled out at the end of its lifespan or with replacement of the asphalt; the supplier must demonstrate that the housing has a durability lasting at least 20 years.
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From page 15... ...
For instance, it might be inferred that intersection stop bars equipped with IPM systems may experience similar benefits related to reduced vehicle approach speeds and increased vehicle compliance as those observed for pedestrian crosswalks. Airport Runways and Taxiways Published information related to the use of IPM systems on airport runways and taxiways focused predominantly on the evolution of technology from tungsten bulbs, which were expensive to install and maintain, to LED light sources, which were found to be less expensive to install and operate.
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From page 16... ...
Specific to halogen light sources, halogen lamps reportedly experienced frequent water condensation and broken filaments. Applying more generally to all IPM system marker types, recessed markers require frequent cleaning to eliminate dirt and debris from the lens surface.
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From page 17... ...
Instead, prior studies have considered various surrogate safety measures including enhanced driver awareness, increased vehicle yielding, reduced vehicle speeds, or reduced vehicle–pedestrian conflicts (defined as a 18 vehicle and a pedestrian in a crosswalk at the same time)
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