{'fraction_non_alphanumeric': 0.018877551020408164, 'fraction_numerical': 0.0005102040816326531, 'mean_word_length': 5.9786476868327405, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Evaluation of Enhanced Brake Lights Using Surrogate Safety Metrics. Task 1 Report: Further Characterization and Development of Rear Brake Light Signals

This report details a series of interrelated research studies and supporting activities intended to further characterize and develop rear brake light signals likely to improve driver reaction to hard braking lead vehicle events, emphasizing unique and novel approaches not previously studied. The first study, LED optimization, characterized a sample of existing, commercially available automotive LED brake light arrays and documented the current state-of-the-art for LED technology. This work also developed optimized signal lighting configurations, including specifications for LED signal approaches (flash frequencies, brightness levels, patterns). The second empirical study (static testing) narrowed the pool of available signal approaches using static field evaluations intended to assess subjective impressions of signal attributes (attention-getting and glare) as well as eye-drawing capability of candidate signals for drivers who were looking away from the forward view. The third study (public roadway evaluation) captured driver responses to signal activations under naturalistic settings via observational methods using vehicles equipped with candidate signals and on-board instrumentation. This onroad study also addressed unintended consequences associated with the novel experimental signal approaches. Each step along this research path was intended to further refine signal attributes and narrow the set of candidate signals for downstream evaluation. Analytic activity was also undertaken in order to further the development of system specifications, including developing a scientific basis for activation criteria and thresholds and special cases for open loop enhanced rear lighting. Together, this work increased the state-of-knowledge and development of rear-brake signal approaches.