|The Transportation Lighting Alliance (TLA) has released more reports regarding some of its research into lighting for vehicles and roadways.
The TLA is a group of vehicle lighting manufacturers, government agencies, and the Lighting Research Center (LRC). The TLA conducts cooperative research and education on the roadway visibility system, which includes vehicles, roadways, signage, and signals. You can learn more about the TLA, including its members, at www.lrc.rpi.edu/programs/transportation/tla/.
TLA reports are available online at www.lrc.rpi.edu/programs/transportation/TLA/publicInformation.asp. These reports include:
Vehicle Forward Lighting: Optimizing for Visibility and Comfort – a TLA Scoping Study (TLA2004-01)
This 33-page report outlines a literature review performed by the LRC to identify opportunities and to suggest priorities for further understanding of vehicle forward lighting and how it can be best optimized for visibility and comfort. The report discusses characteristics of forward lighting with respect to different methods used to understand them: analytical methods based on calculations; short-term laboratory and field studies that directly measure lighting or human responses to lighting; and long-term laboratory and field studies that use simulation or observation.
Optimization of Forward Lighting: Headlamp Intensity and Visibility along Curves (TLA2005-01)
This 20-page report details a field study conducted by the LRC to measure peripheral visual performance under various headlamp conditions, including conditions typical of halogen and high-intensity discharge (HID) headlamps. The study simulated an approach of left- and right-hand turns using targets located along the edges of the curves, including different headlamp illumination conditions. The study found that the configuration with illuminance conditions most representative of HID headlamps resulted in improved target detection over the configuration most closely matching the illuminance profile of halogen headlamps.
Spectral Effects of LED Forward Lighting (TLA2005-02)
This 19-page report looks at light-emitting-diode (LED) forward lighting systems for vehicles. LED forward lighting systems soon will become a reality on today’s roadways. One aspect of LED light sources that will differ significantly from tungsten halogen (TH) or high-intensity discharge (HID) lamps is their spectral power distribution (SPD). Lamp SPD can have considerable impacts on a driver’s visual performance. Recent studies have shown that headlamp sources that have more energy in the short-wavelength region of the visible spectrum provide benefits to the vehicle operator for off-axis target detection.
Optimization of Forward Lighting: Visibility and Headlamp Performance Along High-Speed Curves (TLA2006-01)
This 18-page report details a field study conducted by the LRC to characterize the impact of headlamp intensity on visual detection of small targets when entering high-speed curves. The study explored the impacts of target location and reflectance, headlamp illumination, and location of a secondary tracking task on detection of small targets located along curves. The study results demonstrated that the relationship between headlamp intensity and visual performance depends upon the target’s location and the amount of light on the target.
The Influence of Dynamic Lighting Conditions on Visibility: A Pilot Study (TLA2006-02)
This 17-page report details a pilot laboratory study that investigated the influence of dynamic lighting conditions on peripheral visibility. The study measured the effects of dynamic changes in light level on target detection performance. The scientists found that most of the LED sources analyzed can theoretically result in increased off-axis visual performance over current headlamp technology. The results of these calculations are compared to field studies of headlamp spectra to determine the magnitude of these effects as potentially seen in practice.