Martin T. Pietrucha

FIELD STUDIES OF PEDESTRIAN WALKING SPEED AND START-UP TIME

Todays traffic environment is not well adapted to the needs of the older pedestrian. Unfortunately, except in the case of children, little is known about the characteristics and behavior of pedestrians. Although the simple fact that older pedestrians walk more slowly than younger ones is easily supported by field data, existing data on walking speeds and start-up time (i.e., the time from the onset of a Walk signal until the pedestrian steps off the curb) have many shortcomings. A series of field studies was conducted to quantify the walking speed and start-up time of pedestrians of various ages under different conditions. Sixteen crosswalks in four urban areas were studied. Data were collected on walking speeds and start-up times relative to site and environmental factors, including street width, posted speed, curb height, grade, number of vehicle travel lanes, signal cycle length, pedestrian-signal type, street functional classification, crosswalk type, and channelization. Data on a subject group of pe...

EFFECTS OF FONT AND CAPITALIZATION ON LEGIBILITY OF GUIDE SIGNS

The research objective was to improve highway guide sign legibility by replacing the 40-year-old guide sign font with a new font called Clearview. It was believed that the current guide sign font’s thick stroke design, made with high-brightness materials and displayed to older vehicle operators, exhibited a phenomenon known as irradiation or halation. Irradiation becomes a problem if a stroke is so bright that it visually bleeds into the character’s open spaces, creating a blobbing effect that reduces legibility. The Clearview font’s wider open spaces allow irradiation without decreasing the distance at which the alphabet is legible. Results are presented of two daytime and two nighttime controlled field experiments that exposed 48 older drivers to high-brightness guide signs displaying either the current or the Clearview font. The Clearview font allowed nighttime recognition distances 16 percent greater than those allowed by the Standard Highway Series E(M) font, without increasing overall sign dimensions.

Cross-Median Collisions on Pennsylvania Interstates and Expressways

Cross-median collisions (CMCs) on high functional class roadways are a concern because of the potential economic and social losses that often accompany these crashes. The Pennsylvania Department of Transportation (PENNDOT) design policy suggests protecting medians on divided highways where the median width is less than 10m (32.8 ft) and the average daily traffic is above 20,000 vehicles per day. However, CMC crashes have occurred where a barrier was not warranted by the policy. The methodology used to assess median safety on Interstates and expressways in Pennsylvania is reviewed, and the findings are reported. A critical review of literature and an assessment of various state department of transportation median safety practices were undertaken. An expert panel qualitatively assessed median safety practices and provided input for quantitative data collection. Two PENNDOT databases, police accident reports, photologs, and field data were analyzed to complement the qualitative findings. Qualitative results suggest that the three-strand cable system, strong-post W-beam guiderail, or the concrete safety shape are recommended median barriers in appropriate site conditions. Quantitative results show that CMC crashes are rare events; however, nearly 15% involve fatalities and 72% involve nonfatal injuries. In addition, CMC crash rates at earth-divided highways decrease as the median width increases, CMC crashes appear more likely to occur downstream of interchange entrance ramps, and CMC crashes are more likely to involve adverse pavement surface conditions (wet or icy) than are other crashes. Negative binomial regression models were used to model CMC crash frequencies on earth-divided highways.

Use of fuzzy sets to evaluate driver perception of variable message signs

Current methods for evaluating the quality of service provided by a variable message sign (VMS) may not yield results that represent the satisfaction drivers experience because these techniques cannot represent the variability and complexity of human perception with great fidelity. To solve those problems, a new method that applies fuzzy set theory was developed. Results of a preexisting survey of VMS service quality were reanalyzed with this method. For this application, two membership functions were constructed with two different experimental methods: interval estimation and pairwise comparison. Specifically, construction of the second membership function used Saatys eigenvector method. These two membership functions employ five linguistic statements to represent the degree of satisfaction and relative importance of six performance criteria. Quality of VMS service perceived by an individual driver was evaluated with the concept of the fuzzy weighted average. A set of 322 quality measures was computed, ...

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.

Systems and scenarios for a philosophy of engineering

Abstract Nano-, bio-, and information based engineered systems as well as large-scale socio-technological systems, such as the electric grid and the regional surface transportation network, are complex systems for which the temporal evolution and outcomes states may not be predictable because emergent phenomena are ubiquitous. Given that engineers may not be capable of predicting the outcome of an engineered system, the issue arises as to how engineers ensure system performance and engineer ethically. A pragmatic philosophy of engineering with both instrumental and reflective aspects is essential. This philosophy will incorporate both systems analysis and scenario planning as tools to learn about how a system may perform over time, and engineers may thereby gain insight to how they ought design and manage complex systems even though they may not fully understand them. The creation of feedback mechanisms by using such tools as the semantic World Wide Web may be one way that a reflective dialogue about engineering systems emerges and influences the evolution of these complex systems.

Letter Legibility for Signs and Other Large Format Applications

Numerous studies have evaluated the legibility of various fonts displayed in small print. There has also been a great deal of research into the legibility and recognition of standard highway sign alphabets. There has, however been no attempt to empirically determine large format distance legibility for the growing number of fonts currently available to non-transportation sign manufacturers. The present study systematically evaluated the letter legibility of a set of fonts that are consistent with commercial (e.g., storefront), industrial, transit, and highway signage. The fonts were evaluated in a laboratory setting. Individual test charts were designed for each of the fonts based on the standard Snellen distance visual acuity chart. Recognition acuity thresholds for each of the fonts yielded the minimum visual angle of letter height necessary for their resolution. The relative legibility of each font is discussed, as is the effect of font choice on sign size, and theoretical issues related to critical detail for letter recognition acuity.

Examining fatal crash reductions by first harmful events since the introduction of the Federal Highway Safety Improvement Program

The federal Highway Safety Improvement Program (HSIP) has been associated with the reduction in fatal crashes since 2006, but the reasons for the reduction remain largely unknown. This paper examines the reduction in fatal crashes in terms of different types of first harmful events that can provide insight into crash causes and prevention strategies. In this study, fatal crashes were categorized into four types: overturn, collision with motor vehicle in transport, collision with fixed object, and collision with nonmotorist. Fixed-effects and mixed-effects Poisson models were used to estimate the magnitudes of fatal crash reduction by first harmful events for each state. Fatal crashes due to collisions with nonmotorists and motor vehicles in transport have been reduced by 10% and 5.3%, respectively, compared with the 2001 to 2005 period. Fatal crashes due to overturn and collision with a fixed object decreased in some states but remained unchanged or increased in other states. Nevertheless, the numbers of national fixed-object and overturn fatal crashes have been reduced by 3% and 0.7%, respectively, as a whole. This study also investigated possibilities that could be associated with the magnitudes of the reductions, for example, the different traffic laws among states. It was found that although different safety improvement projects were implemented to target the various types of crashes, the improvements were also likely to be beneficial to other crash types. These are referred to as spillover effects. Nationally, fatal crashes have decreased since the introduction of the HSIP partly because of the reduction in fatal crashes due to collisions with nonmotorists and motor vehicles in transport and partly because of spillover effects.

Development of a New Guide Sign Alphabet

The research objective was to improve highway guide sign readability by replacing the current 40 year old guide sign font with a new font called Clearview. The rationale behind the research was the belief that the current guide sign font’s thick stroke design, when coupled with high brightness, results in a phenomenon known as irradiation, or halation. Irradiation becomes a problem when a character’s stroke is so bright that it bleeds into the character’s open spaces, creating a blobbing effect that reduces letter legibility. The Clearview font’s design was intended to widen the open spaces, thereby allowing irradiation without diminishing the distance at which the alphabet could be read. A controlled field experiment exposed older drivers to high-brightness guide signs displaying either the current or the Clearview font. Mean nighttime word legibility was improved by up to 22 percent, and mean word recognition distance increased by 16 percent with the Clearview font. In addition, the reading distance of words depicted in a standard highway all-uppercase font was compared with words shown in a mixed-case font; that is, with lowercase letters and an initial capital. In a legibility task, where individual letter reading is required, the larger uppercase letters resulted in greater legibility distances than those of the smaller mixed-case, but when the mixed-case font was increased in size so that mixed-case words used the same sign area as uppercase words, performance for the two was the same. When using word recognition as the dependent measure, where the task is discrimination of global word form, or “footprint,” the smaller mixed-case words were read at the same distance as the larger uppercase words. When the mixed-case font was increased in size so that mixed-case words used the same sign area as uppercase words, the mixed-case words were readable from significantly further away.

Evaluation of Effectiveness of the Federal Highway Safety Improvement Program

The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users established the Highway Safety Improvement Program (HSIP), which authorized about