Visibility Of Signs Research Articles

Visual functions of older people and visibility of traffic signs

Two age-related changes of visual functions such as luminous efficiency and visual acuity were investigated in relation to visibility of traffic signs. The loss of luminous efficiency in the short-wave region (blue lights) and the decrease of visual acuity in near sight are remarkable changes of the functions with aging. Visibility change of visual signs associated with these changes was evaluated quantitatively.

トンネル内標識の視認性に関する検討

トンネル内標識の視認性に関する検討

It's All a Matter of Timing: Sign Visibility and Sign Reference in Deaf and Hearing Mothers of 18-Month-Old Children.

The signed and spoken language produced by 14 mothers to their 18-month-old children during free play was analyzed. All the children had profound prelingual deafness. Seven of the mothers were profoundly deaf and fluent users of British Sign Language (BSL) or Auslan. The other seven were hearing and had enrolled in a signing program. Maternal signed utterances were classified according to whether they were made in the child's line of sight and whether they had a salient context; that is, they referred to an object or event at the child's current focus of attention. Spoken utterances were coded by word length. Comparisons between the two groups showed that both deaf and hearing mothers produced a majority of single-sign utterances (rather than utterances containing two or more signs). Deaf mothers also produced a majority of single-word spoken utterances, whereas the hearing mothers produced a significantly greater proportion of multiword utterances. As predicted, deaf mothers were more successful than hearing mothers in presenting signed utterances with a salient context that were visible to their children. Across the group as a whole, the total number of visible and salient signed utterances produced in 10 minutes was positively correlated with the total number of occasions on which mothers successfully redirected their child's attention or the child spontaneously turned to look at the mother. This suggests that deaf children who are visually attentive to their mothers receive a greater number of visible signed utterances with a salient context. I argue that this provides a more secure context for early language development.

The use of parking and auxiliary lamps for traffic sign illumination

Problem: In 1997, the U.S. government introduced an option of having headlamps labeled as visually/optically aimable (VOA). To be so labeled, the vertical gradient of the light output needs to meet certain minimum requirements. A concern with VOA lamps is that they might provide less light above the horizontal than conventional U.S. lamps, thus reducing the effectiveness of retroreflective traffic signs. Method: This study examined 36 first-generation VOA lamps to assess the reduction of light above the horizontal. Furthermore, this study addressed the possibility of maintaining the status quo of light for sign visibility by supplementing light from VOA lamps with light from either parking lamps or an auxiliary lamp mounted just above the driver. Results: The results indicate that parking lamps are too weak to be able to make up for the deficit. A lamp mounted on the roof just above the driver would provide a substantial advantage over headlamps in terms of retroreflective geometry because the observation angles for such a lamp are smaller than for either headlamp. However, even taking into account this advantage, a single such lamp would need to have peak intensity between 1500 and 2000 cd to make up for the deficit created by a pair of VOA headlamps. Impact on industry: The present findings imply that neither parking lamps nor auxiliary lamps mounted just above the driver will likely be a practical solution for the reduced light output above the horizontal from VOA lamps.

Sign Retroreflectivity: Comparing Results of Nighttime Visual Inspections with Application of Minimum Retroreflectivity Values

In 1993, FHWA published research recommendations for minimum levels of retroreflectivity for traffic signs. These values were later revised in a 1998 FHWA report. The minimum values were developed as part of a process to add end-of-service life retroreflectivity values to the Manual on Uniform Traffic Control Devices. There have been few or no comparisons between the use of minimum retroreflectivity values to define end-of-service life and the results of typical nighttime visual inspections. Researchers at the Texas Transportation Institute conducted such an evaluation as part of a Texas Department of Transportation (TxDOT) sign workshop. In the evaluation, TxDOT sign crews evaluated 49 signs on an 8-km (5-mi) closed course. Each sign was rated as “acceptable,” “marginal,” or “unacceptable.” Vehicle headlamp illuminance was also measured. The results of the evaluations were compared with the application of the FHWA minimum values. The results show that whereas one sign did not meet the low-speed FHWA minimum values, the average ratings for the TxDOT sign crews indicated that 26 signs were not acceptable. The researchers identified several factors that affected the average sign ratings. These factors included the uniformity of the sign face, the type of sheeting material, and the retroreflectivity. The findings indicate that among the TxDOT sign crews participating in the evaluation, visual nighttime inspections result in a higher failing rate than does the application of the FHWA research recommendations for minimum levels of retroreflectivity. This finding indicates that visual sign inspections should be an important component of assessing the nighttime visibility of traffic signs.

Performance in smoke of wayguidance systems

Norwegian experiments on human behaviour in smoke have been re-analysed with respect to evaluating and quantifying performance parameters adequate for fire safety design according to modern principles of fire safety engineering. Two generic performance parameters are quantified; the movement speed and the probability of making the correct decision in a decision element of an escape path. For low location lighting (LLL) systems designed according to the specifications of IMO, movement speed might be rather insensitive of the type of wayguidance system, even though higher luminance of electrically powered (EP) than photoluminescent (PL) systems. The human performance of making the correct decision in a decision element was found to vary between 70% and 80%, and also irrespective of the type of LLL system. Other types of wayguidance systems have performance greater than 90% with respect to making the correct decision, but these do not comply with the existing pre-scriptive code specifications. The probability of wayfinding and successful escape depends on the correct decision in each decision element in the escape path and identification of exits. Therefore the probability of successful escape diminishes sharply as a function of both the number of decision elements and the performance of the wayguidance system. Unfortunately there are still missing performance requirements for both the geometry of escape paths and the visibility and recognition of safety signs. Copyright © 1999 John Wiley & Sons, Ltd.

Quantitative comparisons of factors influencing the performance of low-beam headlamps

This study compared the quantitative influence of a variety of factors on the performance of low-beam headlamps. The following factors were included: vertical aim, horizontal aim, mounting height, lateral separation, lens dirt, lamp voltage, number of functioning lamps (two vs. one), vehicle type (cars vs. light trucks and vans), beam pattern (U.S. vs. European), and light source (unshielded 9007 vs. a shielded H4). The following aspects of headlamp performance were considered: visibility of pedestrians, visibility of road delineation, visibility of vehicle reflex reflectors, visibility of retroreflective traffic signs, visibility of targets near the road expansion point, glare directed towards oncoming drivers, glare reflected from wet pavements towards oncoming drivers, glare directed towards rearview mirrors of preceding vehicles, and foreground illumination. A market-weighted U.S, beam pattern with lamps mounted at market-weighted locations, formed the basis for most of the analyses. The results indicate that from among the factors studied, vertical aim is overwhelmingly the most important factor in influencing the performance of low-beam headlamps. The second most important factor is the number of functioning lamps. The main implication of this study is that major improvements in current (fixed as opposed to adaptive) low-beam headlighting could be achieved primarily by better control of vertical aim and by longer-life headlamps.

Evaluation of Unassigned Sign Colors for Incident Management Trailblazing

Efforts to design and evaluate a new sign design for incident route trailblazing are reported here. Phase 1 was an off-road field experiment conducted to determine the best sign color combination, letter stroke width, and letter size for emergency signs. Based on the results of Phase 1, three color combinations were chosen for testing (black on coral, black on light blue, and yellow on purple) against a baseline color combination of black on orange. Phase 2 was conducted with an instrumented vehicle through a construction zone-related detour. Questionnaire data were also obtained. The independent variables of interest were sign color combination, age, and visibility condition. The findings of Phase 2 indicated that use of a color combination other than the traditional black-on-orange sign would improve driver performance and safety when used for trailblazing during critical incidents. The following conclusions were reached: ( a) yellow on purple or black on light blue will likely result in fewer late-braking maneuvers if the road geometry includes many tight curves; ( b) black on light blue will result in the fewest number of turn errors; ( c) black on orange will result in more turn errors, especially during the day and particularly when it is overlapped with existing detour and construction zone signs; ( d) black on coral is least preferred by older and younger drivers; and ( e) younger drivers tend to prefer yellow on purple and older drivers tend to prefer black on light blue.

Clearer Road Signs Ahead

To address issues of legibility and visibility of road signs from a distance and at night, a new font, named Clearview, was developed by Meeker & Associates and tested by the Pennsylvania Transportation Institute (PTI) at Pennsylvania State University. After creating initial versions of the fonts, the authors subjected them to an iterative design process based on the results of subjective field evaluations, objective tests of the typefaces' degradability, and objective laboratory studies using computer simulation. The steps in this evaluation process are described here.

Model Guidelines for Visibility of On-Premise Advertisement Signs

On-premise advertising signs play an important role in directing drivers. Well-placed and well-designed on-premise advertising signs can guide vehicle operators toward their destinations with minimal demand for attention. Poor placement of signs can sap a driver’s cognitive and perceptual resources, resulting in erratic maneuvers such as inappropriate slowing and lane changing. Increasingly, however, the visibility of on-premise advertising signs is being determined not by human factors researchers, visibility experts, or traffic engineers but by local planning and zoning officials, who lack specialized training in relevant fields. Regulations affecting on-premise sign visibility characteristics, such as means of illumination, lateral offset, and sign size, have been established mainly on the basis of arguments for improved aesthetic appeal and of vague, often unsubstantiated safety claims. There is a clear need to determine, from scientific and ergonomic perspectives, the effects these regulations have on sign visibility and traffic safety. An organized synthesis of existing literature on sign visibility based on 60 years of research and consisting of more than 150 journal articles and technical reports is presented. The synthesis may be used by sign designers to optimize the visual effectiveness of their signs. It also can provide a scientific basis for the development of new on-premise sign regulations or changes to existing regulations. A model set of guidelines for designing and locating on-premise advertisement signs for conspicuity and legibility is provided.

Visibility of Text and Icon Highway Signs under Dynamic Viewing Conditions

Threshold sizes for accurate identification were determined for three different types of highway signs (text, icon, and modified icon) under two conditions of horizontal target motion (60° and 120° per second). The two iconic versions were superior to the text version in nearly all cases, and this benefit of the pictorial format was even more pronounced in the higher-velocity condition. The advantage of the modified icon signs over the standard icon signs that had been determined in previous work was replicated here under the low-velocity condition but essentially disappeared under the higher-velocity condition. Sign-reading performance was found to be related to dynamic visual acuity (with Landolt-C targets) under the two velocity conditions. Results are discussed in terms of the “low-pass format” for sign design suggested by previous researchers and in terms of the potential utility of dynamic acuity for the driving setting.

Influence of Visual Environments on Visibility of Traffic Signs

Japan uses its limited land area intensely and many businesses are located along roads. Because of insufficient regulations in Japan, advertising signs such as billboards are more prevalent there than in Europe and America. Road signs, therefore, are more difficult to recognize, because they may be hidden among such commercial and other signs. The amount of information along roads that is not required for driving, such as billboards and signs on electric poles, is measured and the detectability of road signs is investigated quantitatively through actual road tests. The ratio of area of clutter signs to the total area of the field of view was called the visual noise ratio. Investigation of the relationship between the distance at which a driver first recognized a highway number sign and the visual noise ratio revealed a negative correlation. Differences between the sexes were also observed; for example, female drivers were less affected by the visual noise ratio, but their absolute visible distances were shorter than those of male drivers.

Influence of Visual Environments on Visibility of Traffic Signs

Japan uses its limited land area intensely and many businesses are located along roads. Because of insufficient regulations in Japan, advertising signs such as billboards are more prevalent there than in Europe and America. Road signs, therefore, are more difficult to recognize, because they may be hidden among such commercial and other signs. The amount of information along roads that is not required for driving, such as billboards and signs on electric poles, is measured and the detectability of road signs is investigated quantitatively through actual road tests. The ratio of area of clutter signs to the total area of the field of view was called the visual noise ratio. Investigation of the relationship between the distance at which a driver first recognized a highway number sign and the visual noise ratio revealed a negative correlation. Differences between the sexes were also observed; for example, female drivers were less affected by the visual noise ratio, but their absolute visible distances were shorter than those of male drivers.

A Study on the Visibility of Chromatic Indication Signs

A Study on the Visibility of Chromatic Indication Signs

Classifying urban crashes for countermeasure development

Efforts to reduce urban crash rates have been hampered by a lack of information about motor vehicle crash types. The present study is based on a systematic sample of 4,526 police crash reports from four urban areas. The sample was weighted to give each area equal representation. Diagrams and narrative descriptions from each report were reviewed, and the most common crash types based on precrash driver/ vehicle behavior, were identified. Fourteen crash types were defined, and five of these were found to account for 76% of all crash events and 83% of injury crashes. Although the rank order of the five types differed from city to city, they accounted for the vast majority (69%–81%) of the crashes in each. Potential countermeasures are discussed based on the predominant crash types identified in this study. For example, ran traffic control crashes, the most common type, might be reduced by changes in signal timing, providing all-red signal intervals, increasing sign visibility, and increasing sight distances.

Visibility of exit signs in clear and smoky conditions

Visibility of exit signs in clear and smoky conditions

Visibility of exit signs in clear and smokey conditions : Collins, B L, Dahir, M S and Madrzykowski, D in IESNA Ann Conf Tech Papers, Montreal, Canada, 11–15 August 1991. Illuminating Engineering Society of North America, New York (1991) pp 13–35 (21 refs)

Visibility of exit signs in clear and smokey conditions : Collins, B L, Dahir, M S and Madrzykowski, D in IESNA Ann Conf Tech Papers, Montreal, Canada, 11–15 August 1991. Illuminating Engineering Society of North America, New York (1991) pp 13–35 (21 refs)

The visibility of symbolic highway signs can be increased among drivers of all ages.

Visibility and comprehension of standard text, standard symbolic, and improved symbolic highway signs were compared among young, middle-aged, and elderly observers. The average distance at which standard symbolic signs could be identified was about two times that of text signs for all three age groups. The visibility distances of the improved symbolic signs, which were designed using an optical blur (i.e., low-pass) approach in order to avoid higher spatial frequencies, exceeded those of both text and standard symbolic signs. Visibility distance was decreased significantly among older drivers on some signs but not others. There were no significant age differences in the comprehension of symbolic signs. Acuity, a good predictor of visibility distance of both text and standard symbolic signs, was only weakly related to the visibility distance of the improved symbolic signs. These findings demonstrate that low-pass symbolic signs have significant advantages in visibility over their test counterparts for all drivers.

Visibility of Exit Signs in Clear and Smoky Conditions

Visibility of Exit Signs in Clear and Smoky Conditions

Visibility of Exit Signs and Directional Indicators

Visibility of Exit Signs and Directional Indicators