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There is currently no commonly accepted or adopted measure of pedestrian and bicycle exposure to risk. Consequently, a large portion of the field of pedestrian and bicycle safety is lacking an adequate means to evaluate the effectiveness of its efforts. The current study presents a proposed metric for measuring pedestrian and bicycle exposure to risk: hundred million pedestrian or bicycle miles of roadway (or other motor vehicle shared facility) traveled. A method for implementing the proposed exposure metric is described for eight shared-facility types characteristic of the urban environment of Washington, D.C. These facilities include three types of intersections, midblock road segments, driveways, alleys, parking lots, parking garages, school areas, and areas with playing, dashing, and working in the roadway. The methodology is then used to calculate the annual pedestrian and bicycle exposure for the city for the calendar year 2007. The results of these calculations revealed 0.82 hundred million miles for pedestrian exposure and 0.37 hundred million miles for bicyclist exposure. In this way both the feasibility and scalability of the proposed metric were successfully demonstrated for a relatively large urban environment. Thus the proposed metric has the potential to eliminate one of the major obstacles in the pedestrian and bicycle safety field, the lack of adequate exposure data. Although further refinement and validation are still needed, the proposed metric provides a possible initial foundation to develop a national unit of risk exposure for pedestrians and bicyclists.

The FHWA Turner-Fairbank Highway Research Center is undertaking a research program to study the visibility of retroreflective raised pavement markers (RRPMs). The focus of the initial effort is to determine the relative luminance of RRPMs and pavement markings (PMs) needed to produce adequate guidance on rural two-lane roadways at night. A driving simulator was used to test 36 research participants as they drove simulated roadways containing various combinations of RRPMs and PMs. The luminance of the simulated roadway delineation ranged from 0.07 to 4.1 cd/m2. The primary driver performance measure was curve-recognition distance. For the various RRPM and PM luminance conditions, mean curve-recognition distances ranged from 19.0 m (62.3 ft) to 68.4 m (224 ft), with a grand mean of 43.0 m (141 ft). Regression analyses produced predictive equations to estimate the mean curve-recognition distance from the luminance of RRPMs acting alone or of PMs acting alone. Trading ratios were computed for PM luminance with and without RRPMs present on the road. A conservative empirical estimate of 0.52 was computed for such a trading ratio based on the data from the current experiment. This value compared favorably with independent estimates of 0.54 and 0.55 based on an earlier analytical approach. Thus, the current experiment confirmed, with empirical data, earlier estimates that it might be possible to reduce the luminance of PMs on rural two-lane roads by about 45% when appropriate RRPMs are installed.

NASA is developing space telerobotic systems to construct, service and maintain complex space hardware. These systems will be controlled by an astronaut operator in space. Preliminary mission procedures have been developed and typical task elements have been selected. The present study simulates some of these procedures, tasks and devices in the laboratory in order to obtain initial operator/robot system performance data.

A Driving Fitness Form was developed to ensure that drivers areready to participate in field driving experiments at night. The form was tested in afield experiment conducted in Delta, Pennsylvania, during August 2004. The fieldexperiment was part of a cooperative research program conducted by the FederalHighway Administration and the Pennsylvania Department of Transportation.Sixteen research participants drove a curvy stretch of rural two-lane highway eachnight for 8 nights with different pavement markings and markers on the roadway.Partly due to the Driving Fitness Form, the experiment was completedsuccessfully by all participants without any incidents or crashes. The DrivingFitness Form performed well, and summary data were collected on the sample of16 drivers.

An experiment was conducted to simulate executing a proposed on-orbit Space Station maintenance task by means of a telerobotic system. A battery Orbital Replacement Unit (ORU) changeout task was simulated in the laboratory. This task was performed by 5 experienced robot operators using full-scale mockups of the ORU battery module and its interfaces. The space telerobot was emulated by a pair of Kraft robot arms mounted on a Cimcorp gantry robot. The results of the experiment demonstrated that the preliminary flight procedures defining the ORU changeout task worked well. The results also showed that the basic hardware design for the battery ORU could be manipulated by the telerobot. The effects of operator training were significant. Average task completion times improved almost 40 percent over 8 trials. The effects of training were not as pronounced on measures of performance quality, either in terms of errors made or forces and torques exerted on the ORU. Certain operator interface improvements were suggested.

High school students tapped rapidly on a telegraph key to reduce the intensity of a continuous acoustic stimulus presented through earphones. Failure to respond resulted in an intensity increase of 1 dB every 4 sec. In Experiment 1, a group of 19 students responded to three pure tones (125, 1,000, and 8,000 Hz) and a white noise. The different asymptotic levels observed after 4 min were taken as a measure of equal aversion levels for the stimuli. In Experiment 2, the effect of the starting intensity level (45, 70, and 90 dB SPL) was determined for a 1,000-Hz tone. Differences in the asymptotic intensity levels observed after 6 rain were not significant. In Experiment 3, no significant effect was found upon varying the number of responses required to produce a 1-dB intensity decrement in a 1,000-Hz tone. Together, the experiments demonstrated the feasibility of determining equal-aversion levels for sounds.

A project is underway to investigate human response to transmission line audible noise. This project is developing a psychoacoustic data-base to determine the extent to which present measurement scales and human response criteria are appropriate for evaluating the environmental impact of transmission line audible noise, and to suggest different scales and criteria if necessary. A realistic listening room was used for psychoacoustic experiments in which a listener was given choices between various acoustic environments, including corona sounds, while reading a book. In another experiment groups of participants rated various sounds for their annoyance level while watching television programs. Results indicate that despite its relatively low sound level, corona noise is equally aversive to certain other environmental sounds that are 8 dB higher in sound pressure level. All of the common frequency weighting scales underestimate the aversiveness of corona noise relative to other environmental sounds. From a limited sample of comparison sounds, corona noise was found to be roughly equal in aversiveness to the noise from a room air conditioner. Knowledge of the source of the noise did not affect the relative aversiveness of corona noise as presented in the laboratory. The high-frequency hissing and crackling components of corona noise aremore » more aversive than the low-frequency humming and buzzing components. There are distinctly different kinds of corona noise which differ both in frequency spectrum and relative aversiveness. Thus, in order to assess environmental impact, long-term sampling of corona noise from different lines may be needed. Similar results were obtained from experiments involving reading and television viewing as participant activities, indicating consistent and generalizable findings. (JGB)« less