This study compared the effectiveness of the ITT Night Vision Viewer with the Wide Angle Mobility Lamp (WAML) as low-vision mobility devices for people experiencing night blindness due to retinitis pigmentosa (RP). Both engineering bench testing and functional evaluations were used in the assessments. Engineering evaluations were conducted for (1) consistency of the manufacturer's specifications, (2) ergonomic characteristics, (3) modifications of devices, and (4) pedestrian safety issues. Twenty-seven patients with RP conducted rehabilitation evaluations with each device that included both clinical and functional tests. Both devices improved nighttime travel for people with night blindness as compared with nighttime travel with no device. Overall, the WAML provided better travel efficiency-equivalent to that measured in daytime. Recommendations have been developed on ergonomic factors for both devices. Although some participants preferred the ITT Night Vision Viewer, overall most participants performed better with the WAML.
Traditionally, identification of the Muskingum routing coefficients has been based on observations of the linearity of a loop formed by graphically plotting a forward and a reverse path. This graphical procedure is time‐consuming and may not minimize the error of estimation.
A procedure was developed to improve the drawbacks of the graphical method. This procedure calls for (a) the use of least square regression on the forward and reverse paths to determine their respective slopes, and (b) the use of statistical t‐test to evaluate the hypothesis that these two slopes are equal. The computational procedure is repeated, using incremental values of the flow weighting coefficient, x. A graph of the computed t‐value versus x can be constructed. The optimal value of x, as read from the graph, occurs at the minimum computed t‐value. The procedure has been demonstrated superior to the graphical method for three illustrative examples, resulting in a reduction of the error squares by factors ranging from 5 to 6.
This experiment investigated the effects of word and symbol signs on reaction time and accuracy of response. In addition, a proposed symbol sign, “SCHOOL BUS STOP AHEAD,” was evaluated using the same criteria. A tachistoscope was used to present the visual stimuli for a viewing time of 200 milliseconds. Two sets of conditions were used in the experiment. The first part consisted of a group of subjects that possessed no prior knowledge of/or special education in symbol highway signs. The second part involved a control group who received special training concerning the meaning of symbol highway signs. The stimuli were presented to 20 subjects (both male and female) aged 19 to 45, whose driving experience ranged from 3 to 29 years. The average miles driven per year varied from 1,000 to 20,000 miles. A three factor analysis of variance fixed effect model was used to analyze the data. The main factors of the model consisted of two levels of stimuli (word versus symbol signs), two levels of test conditions (prior knowledge versus no knowledge), and ten levels of different signs (traffic signs). Based upon the analysis of variance results, it was found that symbol signs do convey more accurate identification of road information than do word signs. However, it was not possible to conclude that symbol signs require less time to react to than word signs. The results of this investigation confirmed that neither the word or symbol “SCHOOL BUS STOP AHEAD” sign effectively convey the proper message.
The purpose of this research was to investigate what effect added light and sound stimuli, placed inside an automobile, would have on a driver's braking performance. The research was designed to determine whether a driver's brake reaction time could be decreased by reinforced stimuli and, if s o , which type of the stimuli tested would be most significant in improving a driver's reactions.
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