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Pedestrian accident analysis and reconstruction remain the most difficult areas for the accident analyst. Although data relating to average pedestrian walking speeds, perception-reaction, and pedestrian accident reconstruction can be found in the literature, proper pedestrian study data pertaining to real-life situations are lacking. Pedestrians were observed at signal-controlled crosswalk intersections, and their perception-reaction to the crosswalk signal, acceleration rate to reach constant walking velocity, and average walking speed once steady state velocity is achieved were determined. Experimental test data collected regarding pedestrian gait analysis, initiation, and steady state walking speeds are presented. “Real world” pedestrian observations were gathered at a variety of intersections, ranging from busy downtown intersections to suburban intersections throughout the greater Los Angeles area. Kinematic data on pedestrian movements were obtained using high-speed digital video. A high-speed video motion analysis system was used to reduce the data and to obtain the mean acceleration and time to steady state walking velocity. Perception-reaction data collected on 288 subjects show a significant percentage of the pedestrians initiating movement within 1 s of Walk light illumination. Some differences were observed when the state of anticipation was being considered, and these results are presented. The mean acceleration (0.14 ± 0.09 g) and steady state velocity (1.36 ± 0.24 m/s) values did not demonstrate a significant difference between males and females. The width of the street or initial state of anticipation did not have an effect on either mean acceleration values or steady state velocities.

SUMMARY Dopamine (DA) activates fictive crawling behavior in the medicinal leech. To identify the cellular mechanisms underlying this activation at the level of crawl-specific motoneuronal bursting, we targeted potential cAMP-dependent events that are often activated through DA 1 -like receptor signaling pathways. We found that isolated ganglia produced crawl-like motoneuron bursting after bath application of phosphodiesterase inhibitors (PDIs) that upregulated cAMP. This bursting persisted in salines in which calcium ions were replaced with equimolar cobalt or nickel, but was blocked by riluzole, an inhibitor of a persistent sodium current. PDI-induced bursting contained a number of patterned elements that were statistically similar to those observed during DA-induced fictive crawling, except that one motoneuron (CV) exhibited bursting during the contraction rather than the elongation phase of crawling. Although DA and the PDIs produced similar bursting profiles, intracellular recordings from motoneurons revealed differences in altered membrane properties. For example, DA lowered motoneuron excitability whereas the PDIs increased resting discharge rates. We suggest that PDIs (and DA) activate a sodium-influx-dependent timing mechanism capable of setting the crawl rhythm and that multiple DA receptor subtypes are involved in shaping and modulating the phase relationships and membrane properties of cell-specific members of the crawl network to generate crawling.

Modern controllers permit traffic signals in coordinated systems to operate as pretimed, semiactuated or fully actuated to improve the traffic performance at the particular intersection or over the total system. Criteria were established for selecting the type of control, and timing strategies were developed for signals in coordinated systems. The proposed strategies were evaluated through simulation on 14 representative real-world arterials and grid networks. Based on the analysis of the simulation results, guidelines were formulated to assist practicing traffic engineers in selecting the most appropriate control strategies at specific intersections in coordinated signal systems. The guidelines were then applied to select the type of signal control at several intersections in the City of Los Angeles. The results from before and after field studies indicate that the recommended control strategies improved traffic performance, and the study guidelines can be used as an operating tool for traffic signal management.

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