scholarly journals Evaluating Driver Response to a Dynamic Speed Feedback Sign at a Freeway Exit Ramp Considering the Sign Design Characteristics and Lateral Installation Position

2021 ◽  
Author(s):  
Shakir Mahmud ◽  
Babak Safaei
Keyword(s):  
Lateral Position ◽  
Sign Test ◽  
Detection Range ◽  
Speed Reduction ◽  
Driver Response ◽  
Feedback Sign ◽  
Improved Performance ◽  
Design Characteristics ◽  
Horizontal Curvature ◽  
Exit Ramp

Research was conducted at a freeway exit ramp with significant horizontal curvature to evaluate the effectiveness of dynamic speed feedback signs (DSFS) as a speed reduction countermeasure. Several aspects of the DSFS were evaluated, including display size, border type, lateral installation position, and vehicle detection range. Three different full-matrix DSFS were utilized, which included: 15-inch display panel with yellow border, 18-inch display panel with yellow border, and 18-inch display panel with no border. Each sign was individually installed and tested at identical locations near the start of the exit ramp curve, in both the traditional right-side-mount and an alternative forward-mount within the exit gore area. Speed data and message activation location were collected for vehicles approaching and entering into the curve across the various sign test conditions. Overall, the presence of a DSFS positioned near the start of the curve resulted in curve entry speeds that were, on average, 3.5 mph lower than without a DSFS present at the site. The lowest curve entry speeds were observed for cases where the message activated when vehicles were within 250 to 400 ft of the curve. Interestingly, earlier message activation did not contribute to further speed reductions, although later activation substantially diminished the speed reduction effects. Regarding DSFS lateral position, both the side-mounted and forward-mounted DSFS installations resulted in similar curve entry speeds. Furthermore, there were no discernable differences in curve entry speeds between the 15-inch and 18-inch display panels, although the inclusion of a yellow sign border improved performance.

scholarly journals Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps Based on Sign Location, Interchange Type, and Time of Day

2021 ◽  
pp. 036119812110152
Author(s):  
Md Shakir Mahmud ◽  
Matthew Motz ◽  
Travis Holpuch ◽  
Jordan Hankin ◽  
Anthony J. Ingle ◽  
...  
Keyword(s):  
Time Of Day ◽  
Light Conditions ◽  
Driver Response ◽  
Beneficial Effects ◽  
Passenger Vehicles ◽  
System Versus ◽  
Feedback Sign ◽  
Speed Selection ◽  
Peak Versus ◽  
Horizontal Curvature

A series of field evaluations was performed at three freeway interchange ramps in Michigan that possessed significant horizontal curvature to assess the impacts of a dynamic speed feedback sign (DSFS) on driver speed selection and brake response while approaching and entering the ramp curve. A DSFS with a 15 in. full-matrix display was temporarily installed at each of the three exit ramp locations. The sign was programmed to display the same feedback message at each location, which included the speed number for all approaching vehicles, which alternated with a “Slow Down” message for vehicles approaching above 40 mph. The effectiveness of the feedback sign was tested across various sign locations (at the point of curvature versus 350 ft upstream), interchange types (system versus service), time of day (peak versus off-peak), light conditions (daylight versus darkness), and vehicle types (passenger vehicles versus trucks). Compared with the pre-DSFS site condition, the DSFS reduced curve entry speeds and improved brake response at two of the three ramp locations. In general, the greatest beneficial effects on driver behavior were achieved when the DSFS was positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph. These findings were consistent between the system interchanges and service interchanges, and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared with peak periods and at night. Further evaluation of DSFS at additional ramp locations, and considering an expanded set of conditions, is recommended.

scholarly journals Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps based on Sign Location, Interchange Type, and Time of Day

2020 ◽  
Author(s):  
Shakir Mahmud ◽  
Matthew Motz ◽  
Travis Holpuch ◽  
Anthony J. Ingle ◽  
Timothy Gates ◽  
...  
Keyword(s):  
Substantial Reduction ◽  
Light Condition ◽  
Field Evaluation ◽  
Time Of Day ◽  
Speed Reduction ◽  
Driver Response ◽  
Horizontal Curves ◽  
Before And After ◽  
Feedback Sign ◽  
Straight Segments

Roadway segments that include horizontal curves experience a disproportionate number of crashes compared to straight segments. Many of these crashes are lane departure-related, and excessive speed is often a contributing factor. One particularly vulnerable area for such crashes is freeway interchange ramps, which require a substantial reduction in speed to be safely negotiated. While dynamic speed feedback signs (DSFS) have been found to be an effective speed and crash reduction countermeasure at horizontal curves, the use of such signs on freeway interchange ramps has been limited nationwide. Consequently, the effectiveness of DSFS as a speed reduction countermeasure in such settings has remained largely untested. A before-and-after field evaluation was performed at three freeway exit ramps to assess the impacts of a DSFS on driver speed selection and braking characteristics while approaching and entering the ramp curves. The effectiveness of the feedback sign was tested across various conditions, including sign location, interchange type, time of day, light condition, and vehicle type. In general, the greatest benefits to driver behavior were achieved with the DSFS positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph compared to the pre-DSFS condition. These findings were consistent between the system- and service-interchanges and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared to peak periods and at night. Based on the study findings, the continued use of DSFS as a speed reduction treatment at freeway exit ramps is recommended.

Evaluation of Alternative Messages and Sign Locations on Driver Response to a Dynamic Speed Feedback Sign on a Freeway Interchange Ramp

2020 ◽  
Vol 2674 (12) ◽  
pp. 530-541
Author(s):  
Timothy J. Gates ◽  
Md Shakir Mahmud ◽  
Anthony J. Ingle ◽  
Matthew Motz ◽  
Travis Holpuch ◽  
...  
Keyword(s):  
Driver Behavior ◽  
Field Evaluation ◽  
Speed Reduction ◽  
Driver Response ◽  
Heavy Trucks ◽  
Warning Message ◽  
Feedback Sign ◽  
Speed Management ◽  
Speed Selection ◽  
Advisory Speed

Research was undertaken to determine effective messaging strategies and sign positions for dynamic speed feedback signs (DSFS) when used for speed management at freeway ramp curves. A field evaluation was performed in this setting to assess the impacts of a DSFS on driver speed selection and braking characteristics while approaching and entering the curve. Three feedback messaging strategies were evaluated at three sign positions in advance of the curve. Compared with the existing site (without the DSFS), the DSFS reduced curve entry speeds and improved brake response across all test conditions, particularly for heavy trucks. Overall, considering the combination of both sign position and feedback messaging strategy, the greatest benefits to driver behavior were attained when the DSFS was positioned 255 ft upstream of the curve and the feedback message included the speed number alternating with a SLOW DOWN message. The inclusion of an advisory speed panel with the DSFS did not have a substantive impact on driver behavior. Based on the findings, the continued use of DSFS as a speed reduction treatment at freeway ramp curves is recommended. Specifically, the sign should be positioned to provide adequate time for drivers to perceive and react to the message, such that comfortable braking can be accommodated while approaching the curve. However, the sign should not be placed too far in advance of the curve, as drivers may be more likely to disregard such a premature warning message. Further evaluation of DSFS under various alternative ramp configurations is recommended.

Characterization and Simulation of MIMO Transport Systems in Tape

2013 ◽  
Author(s):  
Giovanni Cherubini ◽  
Angeliki Pantazi ◽  
Jens Jelitto
Keyword(s):  
Block Diagram ◽  
Lateral Position ◽  
Transport Systems ◽  
Tape Transport ◽  
Channel One ◽  
Performance Improvements ◽  
Improved Performance ◽  
The Individual ◽  
Hall Sensors ◽  
Longitudinal Position

The potential for significant capacity and performance improvements in tape storage systems appears to be substantial [1],[2]. Advances in several areas, however, are necessary to foster increases in linear and track densities and consequently achieve higher cartridge capacities and improved performance [3],[4]. Reliable and precise tape transport and track-following servomechanisms are of fundamental importance to guarantee best read-channel performance on all parallel data channels during tape operation. In particular, tight control of tension and potentially of tape-dimensional stability (TDS) variations will be necessary for moving to thinner tape material, which in turn will enable an increase in volumetric density. Figure 1 shows the block diagram of conventional tape transport and track-following servomechanisms in a tape drive [5]. A digital dual servo channel provides estimates of the tape velocity, tape longitudinal position, and head lateral position, which are derived from signals read from dedicated servo bands [6]. Hall sensors provide tape velocity information from the individual reels, which typically is used in the absence of a valid velocity estimate from the servo channel. One of the main impairments affecting the performance of tape drives is the variation of tape tension [7],[8], which may be induced by, e.g., reel eccentricities.

scholarly journals Lambert W Based Speed Reduction Model in Presence of Pedestrian Movements: Case Studies on Undivided Streets

2021 ◽  
pp. 1-16
Author(s):  
Sourabh Thakur
Keyword(s):  
Prediction Model ◽  
Lateral Position ◽  
Lambert W Function ◽  
Speed Reduction ◽  
The Road ◽  
Adverse Impacts ◽  
Traffic Stream ◽  
Speed Prediction ◽  
Standard Section ◽  
Pedestrian Infrastructure

Pedestrian movements sharing right-of-way with vehicular traffic have adverse impacts on the mobility of the traffic stream. Pedestrian movements both along and across the road often force drivers of approaching vehicles either to stop completely or to slow down and change the existing lane. It ultimately results in a decrease in stream speed. With the aim of determining the influence of pedestrian movements, the present study collected traffic data at a standard section (without pedestrian movements) and both traffic and pedestrian data at a pedestrian section (with considerable pedestrian movements). To determine the speed at the standard section, this paper presents a novel ‘Lambert W function’-based speed prediction model in the context of a two-lane undivided urban road. When stream speeds of the pedestrian section were compared to the stream speeds obtained through the speed prediction model at the same traffic volume condition in absence of pedestrians, a significant reduction was observed. This reduction in stream speed is governed by pedestrian parameters. A new pedestrian parameter ‘lateral position of pedestrian from the edge while walking along the road’ was conceived in this study along with few other parameters to predict Percent Speed Reduction (PSR). Intensities of these pedestrian parameters were observed varying over time which results in a high fluctuation in PSR within a range of 29% to 62%. Finally, this investigation forwards an empirical model of Percent Speed Reduction (PSR) to predict the stream speed in the presence of on-street pedestrian movements on undivided urban roads. The outcome of this paper will help transport planners to estimate the efficiency of pedestrian infrastructure projects before implementation.

Driving with a Crt Display

1967 ◽  
Vol 25 (3) ◽  
pp. 899-900 ◽  
Author(s):  
Rudolf G. Mortimer
Keyword(s):  
Peripheral Vision ◽  
Lateral Position ◽  
Lateral Velocity ◽  
Lateral Control ◽  
Improved Performance

Ss drove a car using a synthetic display. Lateral position alone was a weak cue for lateral control. The addition of either lateral velocity or peripheral vision cues greatly improved performance.

Seti Figure of Merit

1997 ◽  
Vol 161 ◽  
pp. 711-717 ◽  
Author(s):  
John W. Dreher ◽  
D. Kent Cullers
Keyword(s):  
Figure Of Merit ◽  
Qualitative Difference ◽  
Current Generation ◽  
Detection Range ◽  
Sky Surveys ◽  
Independent Observations ◽  
Good For

AbstractWe develop a figure of merit for SETI observations which is anexplicitfunction of the EIRP of the transmitters, which allows us to treat sky surveys and targeted searches on the same footing. For each EIRP, we calculate the product of terms measuring the number of stars within detection range, the range of frequencies searched, and the number of independent observations for each star. For a given set of SETI observations, the result is a graph of merit versus transmitter EIRP. We apply this technique to several completed and ongoing SETI programs. The results provide a quantitative confirmation of the expected qualitative difference between sky surveys and targeted searches: the Project Phoenix targeted search is good for finding transmitters in the 109to 1014W range, while the sky surveys do their best at higher powers. Current generation optical SETI is not yet competitive with microwave SETI.

A simple way for producing holographic filters suitable for image improvement

1978 ◽  
Vol 36 (1) ◽  
pp. 226-227
Author(s):  
K.-H. Herrmann ◽  
E. Reuber ◽  
P. Schiske
Keyword(s):  
Transfer Functions ◽  
Diffraction Order ◽  
Lateral Position ◽  
Simple Method ◽  
Spatial Frequencies ◽  
Resolution Electron ◽  
Wiener Filters ◽  
Image Improvement ◽  
Optical Reconstruction ◽  
Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

Toward The Simultaneous Correction of Spherical and Chromatic Aberration in Electron Optics by Means of an Electrostatic Electron Mirror

1990 ◽  
Vol 48 (1) ◽  
pp. 206-207
Author(s):  
Gertrude. F. Rempfer
Keyword(s):  
Chromatic Aberration ◽  
Transverse Magnetic ◽  
Objective Lens ◽  
Ion Imaging ◽  
Corrected Image ◽  
Electric And Magnetic Fields ◽  
Chromatic Aberrations ◽  
Improved Performance ◽  
Electron Microscopes ◽  
Image Planes

Optimum performance in electron and ion imaging instruments, such as electron microscopes and probe-forming instruments, in most cases depends on a compromise either between imaging errors due to spherical and chromatic aberrations and the diffraction error or between the imaging errors and the current in the image. These compromises result in the use of very small angular apertures. Reducing the spherical and chromatic aberration coefficients would permit the use of larger apertures with resulting improved performance, granted that other problems such as incorrect operation of the instrument or spurious disturbances do not interfere. One approach to correcting aberrations which has been investigated extensively is through the use of multipole electric and magnetic fields. Another approach involves the use of foil windows. However, a practical system for correcting spherical and chromatic aberration is not yet available.Our approach to correction of spherical and chromatic aberration makes use of an electrostatic electron mirror. Early studies of the properties of electron mirrors were done by Recknagel. More recently my colleagues and I have studied the properties of the hyperbolic electron mirror as a function of the ratio of accelerating voltage to mirror voltage. The spherical and chromatic aberration coefficients of the mirror are of opposite sign (overcorrected) from those of electron lenses (undercorrected). This important property invites one to find a way to incorporate a correcting mirror in an electron microscope. Unfortunately, the parts of the beam heading toward and away from the mirror must be separated. A transverse magnetic field can separate the beams, but in general the deflection aberrations degrade the image. The key to avoiding the detrimental effects of deflection aberrations is to have deflections take place at image planes. Our separating system is shown in Fig. 1. Deflections take place at the separating magnet and also at two additional magnetic deflectors. The uncorrected magnified image formed by the objective lens is focused in the first deflector, and relay lenses transfer the image to the separating magnet. The interface lens and the hyperbolic mirror acting in zoom fashion return the corrected image to the separating magnet, and the second set of relay lenses transfers the image to the final deflector, where the beam is deflected onto the projection axis.

Response Rates in Online Surveys With Affective Disorder Participants

2020 ◽  
Vol 228 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Tanja Burgard ◽  
Michael Bošnjak ◽  
Nadine Wedderhoff
Keyword(s):  
Meta Analysis ◽  
Response Rates ◽  
Contact Mode ◽  
General Anxiety Disorder ◽  
General Anxiety ◽  
Face To Face ◽  
Survey Participation ◽  
The Mean ◽  
Design Characteristics ◽  
E Mail

Abstract. A meta-analysis was performed to determine whether response rates to online psychology surveys have decreased over time and the effect of specific design characteristics (contact mode, burden of participation, and incentives) on response rates. The meta-analysis is restricted to samples of adults with depression or general anxiety disorder. Time and study design effects are tested using mixed-effects meta-regressions as implemented in the metafor package in R. The mean response rate of the 20 studies fulfilling our meta-analytic inclusion criteria is approximately 43%. Response rates are lower in more recently conducted surveys and in surveys employing longer questionnaires. Furthermore, we found that personal invitations, for example, via telephone or face-to-face contacts, yielded higher response rates compared to e-mail invitations. As predicted by sensitivity reinforcement theory, no effect of incentives on survey participation in this specific group (scoring high on neuroticism) could be observed.

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