Lisa K. Spainhour

Causative Factors and Trends in Florida Pedestrian Crashes

A case study review of 353 fatal pedestrian crashes that occurred in Florida, primarily in 2000, identified contributing causes and trends of predominant pedestrian crash types. Researchers reviewed state records, traffic crash reports, traffic homicide investigative report narratives, diagrams, and photographs and incorporated select accident reconstructions and site visits. Results indicate that the most significant causes of pedestrian crashes are pedestrian behavior, alcohol use by pedestrians and drivers, poor pedestrian visibility at night coupled with violation of driver expectation, and lack of compliance with state laws. Some form of pedestrian behavior was the primary contributing factor in more than three-fourths of the pedestrian crashes reviewed. Alcohol use by the pedestrian or the driver was determined as the primary factor in 45% of the cases. Where alcohol use was determinable, 69% of pedestrians crossing not in crosswalks were under the influence. Dark conditions or insufficient lighting...

Analysis of Fatal Run-Off-the-Road Crashes Involving Overcorrection

In an attempt to identify characteristics that have a strong positive association with overcorrection, data on 579 fatal run-off-the-road (ROR) crashes on state roadways in Florida were analyzed with logistic regression techniques. To overcome shortcomings of traditional analysis methods relying primarily on crash reports, this study relied on case reviews using a broad variety of resources from various disciplines. The data set in this study represents a significant enhancement in accuracy and completeness over that in the initial crash reports; overcorrection was identified using traffic homicide investigation reports. A full model involving 23 explanatory variables was developed, and backward stepwise regression was conducted to identify the most predictive variables. Over-correction cases were strongly associated with alcohol, inattention, high speed, and fatigue and sleeping. Outcomes ranged from roadway departure in the opposite direction, to vehicle impact on returning to the roadway. The study indicated that females were approximately 40% more likely to overcorrect in a fatal ROR crash than males were, with the greatest disparity occurring among middle-aged drivers. Further, while fewer than 20% of fatal ROR crashes occurred where rumble strips were present, drivers were more than 50% more likely to overcorrect than when they were not present. On high-speed (70 mph) roadways with rumble strips, there was almost an 80% higher risk of overcorrection in the crash. Thus, while it appears that rumble strips are effective in preventing many ROR crashes, the contribution of auditory and vibratory sensations of rumble strips to panic oversteering should also be investigated.

Contribution of Behavioral Aspects of Older Drivers to Fatal Traffic Crashes in Florida

Fault in a set of fatal traffic crashes that occurred on state roadways in Florida, primarily in the year 2000, was examined. A case-study approach by a team of trained investigators was taken to examine data compiled from a variety of sources, including traffic homicide reports and crash scene photographs. Crash types were identified in which older drivers were significantly over- and underrepresented in fault. Finally, for crashes in which older drivers were at fault, various contributing factors were identified, including driver errors. Older drivers were overrepresented in fault by a factor of 1.37 compared with younger drivers in the data set. Older drivers were significantly overrepresented in fault in left turn crashes versus oncoming traffic and cross-traffic. Consistent with other work, older drivers were responsible for more intersection than nonintersection crashes. Among other factors, misjudging speeds of other vehicles, failure to observe other vehicles, disregarding traffic signals, and improper (disallowed) left turns were the major driver errors in intersection crashes. Sudden loss of control and driving under the influence of alcohol were the major contributing factors in nonintersection crashes. Approximately 10% of crash contributing factors indicated confusion, inappropriate action, or illegal maneuvers, with more than two-thirds of these cases being attributed to drivers aged 75 years and older. Another important finding of the study is that investigating officers have a tendency to frequently use the term “failure to yield right-of-way,” rather than identifying more specific contributing factors.

Contributing Factors for Young At Fault Drivers in Fatal Traffic Crashes in Florida

This state level case based study is aimed at providing a complete picture of contributing factors for fatal crashes caused by younger drivers (younger than age 25) in Florida. Results showed that nonhuman factors were primary contributing causes in only 6% of the crashes, but secondary and tertiary contributing factors in up to 25% of those crashes. The most common nonhuman factor was tire blowout/tread separation. Common human factors included alcohol use, inattention, and high speed. Younger drivers were at fault in 62% of crashes in which they were involved, and they were highly overrepresented in fault in forward impacts with control loss due to high speeds and abrupt steering input. At the time of the fatal crash, younger drivers were more likely to have had passengers in the vehicle than older drivers and approximately one in four younger at fault drivers was under the influence of alcohol. However, most of the youngest (16 to 17 year olds) at fault drivers were in compliance with nighttime and passenger restriction statutes of graduated driver licensing at the time of the fatal crash. The findings imply that there still remains gaps and weaknesses in current driving programs aimed at younger drivers.

Intermediate Diaphragm and Temperature Effects on Concrete Bridge Performance

A study was conducted to determine the effects of intermediate diaphragms on bridge superstructure performance, combined with actual bearing stiffness and thermal changes. Parameters studied included the presence of intermediate diaphragms, rises and drops in temperature, and increase in bearing stiffness. A finite element model of a bridge superstructure containing Florida Bulb Tee 78 girders was created using ANSYS software. This model was subjected to HL93 truck load as suggested by the AASHTO load and resistance factor design specifications. The results indicate that intermediate diaphragms have the positive effect of reducing the maximum deflections and stresses for the bridge system. The expansion of the bridge due to a positive temperature change was shown to decrease midpoint deflections, and vice versa. The combined effect of intermediate diaphragms and temperature changes increases the effect brought about by the temperature changes.

Modeling Fault in Fatal Pedestrian Crashes by Using Various Data Sources

Binary logistic regression was used to model fault in 318 fatal pedestrian cases that occurred in Florida in the year 2000. The results were used to classify fault and identify factors that influenced fault. An expert fault assessment served as a control for predicting fault in each crash. The expert assessment team conducted a case review of each traffic crash by using additional data sources, such as traffic homicide reports, diagrams, photographs, accident reconstructions, and site visit notes. The logistic models correctly classified fault in anywhere from 84% to 97% of the cases. The existing Florida Department of Transportation algorithm correctly classified fault in only 56% to 58% of the same cases. Improvements in classification accuracy were shown to stem from two sources: the abundance of the data and the improved accuracy of the data. The mental state of the pedestrian and the driver were shown to be important in determining fault. Exhibiting a mental aberration, such as inattention, distraction, perception or decision error, or intoxication, increased the propensity for fault. Issues such as the number of lanes attempted in a crossing, the age of an individual, being a former vehicle occupant, having limited conspicuity, receiving a citation, and wet roads were also shown to be factors significant in determining fault.

Geographic Information System–Based Spatial and Statistical Analysis of Severe Crash Hotspot Accessibility to Hospitals

Previous studies have examined hospital accessibility issues, and other work has exhaustively investigated several aspects of roadway crashes, such as their severity and frequency, possible causal factors, and their clustering on networks. However, the nature of the relationship between them, in the accessibility of severe crash hotspots to hospitals with emergency services, is relatively unexplored. Looking at both elements simultaneously is especially critical, given the need to provide the necessary aid to crash victims in a timely manner to help reduce roadway deaths. To the authors’ knowledge, such an assessment has not been attempted before. The objective of this study was twofold. First, the study investigated accessibility through the use of geographic information systems and statistical analysis to detect high-risk locations. Second, the study used hierarchical multinomial logistic regression analysis to examine several environmental, traffic, and human factors to identify the determinants of the crashes that constitute hotspots. The results show that several roadway segments portend an elevated threat of injury and fatalities for drivers and passengers, not only due to a higher probability of being severely injured, but also because of the low accessibility to hospitals having emergency services. The results suggest that particular spatial, traffic, and roadway factors, such as intersection presence or speed limits, substantially imperil traffic safety. The knowledge gained from this study can help agencies and officials pinpoint and investigate high-risk locations to enhance the safety of roadway users.

Examining Deficiencies in Florida Pedestrian Crash Data

In Florida, the Department of Highway Safety and Motor Vehicles serves as the repository for state traffic crash data collected by law enforcement officers. These state data, which are collected on traffic crash reports, limit the type and the extent of the analysis that can be performed because of constraints and errors in the data. Florida state databases lack information from crash narratives and diagrams, which are not mined for data. In addition, crash report data are shown to contain errors. An analysis was initiated to investigate data from 318 fatal crashes involving pedestrians in which detailed traffic homicide reports and other data sources were consulted. The integrity of the state-maintained data for their accuracy and completeness was investigated. Alcohol usage, fault, speed limits, vehicle speeds, and citations were the leading data fields with errors. In the case of pedestrian alcohol test results, state database records were found to be in error more than half the time. Emphasis is given to the methods that can be used to create a quality crash data set and to highlighting the additional insights that can be gained from the homicide reports and other resources, especially for the accurate determination of fault and crash causation.

Effect of Bearing Stiffness and Skew Angle on Performance of Precast Concrete Bridge

Reinforced elastomeric bearing pads generally support precast concrete bridge girders. The condition of these bearing pads and the pad-bridge interface defines the support boundary conditions of the bridge super-structure. The interface between bearing pads and bridge girders affects the performance of the superstructure and the substructure. The pads are designed to carry vertical loads and to accommodate horizontal movements of the bridge girders. A study was conducted to determine the effects of various parameters on bridge superstructure performance and to compare the girder performance with simple support conditions corresponding to the current Florida Department of Transportation design. A parametric study on the interaction of the support boundary conditions and bridge girders was performed. The parameters studied included the skewness of the bridge and the effect of the bearing stiffness on the bridge system. A finite element model of a bridge superstructure containing Florida bulb tee 78 girders was created using ANSYS software. The model was subjected to an HL93 truck load according to the AASHTO load and resistance factor design specifications. The results indicate that pads with higher bearing stiffness are beneficial to bridges with higher skew angles. However, the reductions in deflections and stresses are smaller for increasing skew angles.

Development of an information model for composites design data

Material properties data, particularly those of advanced composite materials such as fiber-reinforced plastics, provides a very complex domain which is difficult to computerize. As a foundational activity supporting the development of material property databases, we have examined and modeled the data contained within this large, diverse, and intricate domain. Our primary objective was to gain a better understanding of the data involved in this system and their transformation and use. We examined the life cycle of a fiber-reinforced composite material, from a raw material to a manufactured product, focusing on the various applications which require and/or supply materials data and the types of materials data which must be included. A high-level information model was created to illustrate the overall picture of composite materials data which emerged from this analysis. This model provides a global view of the data encompassed in the domain of composite materials, and forms the basis of a formal conceptual model from which databases may be developed.