In 2004, 5,190 people were killed due to a traffic accident involving a commercial motor vehicle (CMV), up from 4,793 people killed in 2001 (Traffic Safety Facts, 2004; Traffic Safety Facts, 2001). Driver drowsiness is an important issue to consider when discussing CMVs. According to the FMCSA, over 750 people are killed and 20,000 people are injured each year due to drowsy CMV drivers (as cited in Advocates for Highway and Auto Safety, 2001). Driver drowsiness is an important issue for CMV drivers for several reasons, including long work shifts, irregular schedules and driving long hours on interstates and highways with no scenic interruptions to help keep the driver alert. Because of these and other factors, including the high mileage exposure that CMV drivers face, drowsiness is an important issue in a CMV driver's occupation. There were two main goals to this research: 1) gain a better understanding of the time-related occurrences of drowsy-related critical incidents (i.e., crashes, near-crashes and crash-relevant conflicts), and 2) obtain drivers' opinions of the 2004 Revised Hours-of-Service regulations. To do this, recent data were used from a Field Operational Test conducted by the Virginia Tech Transportation Institute in which 103 participants drove in an instrumented heavy vehicle for up to 16 weeks; video data, and sensor data were collected from each participant. In addition, actigraph data was collected from 96 of the 103 participants. Each vehicle was instrumented with four video cameras to capture images of the drivers face, the forward roadway, and the adjacent lanes on each side of the truck. In addition, multiple sensors were installed in the vehicle in order to collect data such as the driver's speed, braking patterns and steering wheel movement. These data were combined to provide a complete picture of each driver's environment and behavior while they drove their normal routes. Data analysts reviewed the data for critical incidents (crashes, near-crashes, and crash-relevant conflicts) and determined a drowsiness level for each incident; these downiness levels were compared to drowsiness levels of baseline incidents (i.e., normal driving periods). The results show that drivers were more likely to have a drowsy-related critical incident between 2:00 pm and 2:59 pm. In addition to the video and sensor data, each driver was asked to fill out a subjective questionnaire regarding the revised HOS regulations. Drivers preferred the revised HOS regulations over the old HOS regulations and the number one item that was preferred in the revised HOS regulations is the 34-hour restart which allows drivers to restart their work week by taking off 34 consecutive hours. / Master of Science

This research investigates factors that influence severity of speed-related crashes on mainline roadway segments, with a particular emphasis on comparing single-vehicle and multiple-vehicle incidents and distinguishing between crashes involving legal speed limit violations and those exceeding the maximum safe travel speed as determined by law enforcement. Additionally, it examines significant factors related to classifying a crash as exceeding the maximum safe travel speed. Using crash data from the Traffic Records Electronic Data System (TREDS) for Virginia for 2023, the research employs both Ordinal and Nominal Logistic Regression models for analysis. The findings reveal that higher vehicle speeds before a crash significantly increase crash severity level across all scenarios. Rain and snow/sleet weather conditions exhibit significant impacts on crash outcomes, with adverse conditions often leading to increased severity levels. Roadway characteristics in terms of presence of medians and road surface conditions, are also found to be significant, as are. the driver-related factors of age, safety equipment used, EMS transport after the crash, and vehicle type. The study's comparative analysis between single and multiple vehicles speeding crashes, as well as speeding beyond legal limits and exceeding maximum safe travel speed highlights the contextual differences in crash severity determinants. The findings on classifying crashes as exceeding maximum safe travel speed highlight conditions that influence this designation as well as factors that can lead to inconsistencies in that classification. For example, environmental conditions like rain or snow, certain crash types, and work zone crashes may result in subjective assessments rather than objective determinations. The research offers valuable insights for informing targeted road safety strategies within the Safe System framework – targeted at reducing the severity of speed-related crashes for mainline road segments. The findings support implementing comprehensive strategies that address the complex interplay of speed, road conditions, vehicle characteristics, and driver factors in mitigating crash severity. / Master of Science / This research explores how speeding affects the severity of car crashes, seeking to understand why some accidents are more dangerous than others. By analyzing crash data from Virginia in 2023, the study looks at different types of crash scenarios – those involving just one vehicle and those involving multiple vehicles – and examines how factors like weather, road conditions, vehicle and driver characteristics contribute to the seriousness of these crashes. The research compares crashes where drivers exceed the legal speed limit with those where they drive faster than is safe under the given road conditions. Additionally, it investigates key factors that potentially influence law enforcement at the scene to designate that a crash involves a driver exceeding the safest speed for road and traffic conditions. The findings show that driving at higher speeds before a crash significantly increases the chances of severe injuries or fatalities. The study indicates how weather conditions, design characteristics of roads, or the condition of the road surface, impact crash severity. Driver age and whether drivers were under the influence of alcohol or drugs, and whether vehicle safety equipment like seatbelts were used, are significant in determining the severity of a crash. The findings on classifying crashes as exceeding maximum safe travel speed highlight conditions that influence this designation as well as factors that can lead to inconsistencies in that classification. This research is important because it provides insights for improving road safety.

Yes

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Master of Science / Department of Civil Engineering / Sunanda Dissanayake / Over the past few years, motorcycle fatalities have increased at an alarming rate in the United States. Motorcycle safety issues in Kansas are no different from the national scenario. Accordingly, this study attempted to investigate motorcycle crashes in Kansas to identify critical characteristics and to evaluate the effect of those on motorcycle crash injury outcomes. State-level motorcycle rider fatality rates were investigated while considering various factors including helmet laws, using generalized least squares regression modeling. A detailed characteristic analysis was carried out for motorcycle crashes, using Kansas crash data. Comparisons were made between several aspects of motorcycle crashes and other vehicle crashes. Analysis using Logistic regression was performed on Kansas motorcycle crash data to identify factor affecting fatal motorcycle crashes. In addition, a survey was conducted focusing on identifying motorcycle rider behaviors, helmet usage patterns, perception towards helmet laws in Kansas, potential problems, crash contributory factors, and difficulty levels of different motorcycle maneuvers to execute. Ordered probit modeling was used to identity factors contributing to increased severity of Kansas motorcycle riders involved in crashes. Results from state-level modeling showed statistically significant relationships between motorcycle fatality rates in a given state as well as several other factors. These factors included weather-related conditions, helmet laws, per capita income, highway mileage of rural roads, population density, education, demographic distributions, and motorcycle registrations in the state. The study showed that states with mandatory helmet laws had 5.6% fewer motorcycle fatalities per 10,000 registrations and 7.85% fewer motorcycle fatalities per 100,000 populations. Characteristic analysis of motorcycle crashes in Kansas revealed that motorcycle maneuvers such as overtaking, motorcyclists being older than 40 years, using motorcycle helmets, using motorcycle helmets and eye protection simultaneously, daytime riding, crashes occurring on roadside shoulders, and influence of alcohol among the riders during crashes had higher risk of ending up as a fatal motorcycle crash in Kansas. Results from the survey conducted among motorcycle riders in Kansas revealed that 71% of respondents thought drivers of other vehicles were the single biggest threat to their own safety. Survey results also revealed that 64% of respondents opposed a mandatory law requiring motorcycle riders and passengers to wear helmets in Kansas. Result from the ordered probit modeling of motorcycle rider injury severity showed that overturned and fixed-object motorcycle crashes, helmet use, younger motorcycle riders, speeding, presence of alcohol among motorcycle riders, and good weather contributed to increased severity of injury of motorcycle riders involved in crashes in Kansas.

This thesis looked at traffic crashes in the emirate of Dubai in the United Arab Emirates (UAE) to establish the current situation in road safety and ways of improving it. A global overview of road safety literature revealed that standards of road safety vary widely by region. Key indicators like fatality rate and risk (Jacobs et al, 2000) were found to be higher in most neighbouring Gulf Cooperative Council (GCC) countries (10-25 fatalities/100,000 pop., 3-5 fatalities/10,000 motor vehicles) than in the best-performing Western countries (6 fatalities/100,000 pop., 1 fatality/10,000 motor vehicles). Interventions and countermeasures to tackle specific road safety issues were reviewed from international studies. Countermeasures were chosen with consideration for the local situation in Dubai within the categories of Human, Environmental and Vehicle factors. Examples of selected measures include offending driver punishment (Human), Electronic Stability Control (Vehicle) and central barriers (Environment). These measures were mostly studied in different environments to those in Dubai so the aspect of knowledge transfer between areas of different cultural and environmental conditions was discussed. Data from real world injury crashes (as collected by Dubai Police and the Roads & Transport Authority) over twelve years (1995 2006) were subject to macroanalysis in SPSS to identify the main issues over the past decade. 18,142 crashes involving 30,942 casualties and 48,960 vehicles were analysed at the outset. The following issues were among the main concerns: - High proportion of fatal crashes out of all injury crashes (13.5% compared to 1.4% in the UK); - Most fatal crashes involved a single vehicle hitting a pedestrian; - Most injury crashes involved a single vehicle; - Inconsiderate driving was the most common crash cause cited by the police. Countermeasures found in the literature to counteract these problems were then suggested for application and the estimated savings from applying them were calculated. Savings were quantified as either reductions in casualties or injury crashes. Furthermore, cost savings for the calculated reductions were estimated using existing UK crash costs due to the scarcity of UAE crash cost estimates. Calculation of the estimated improvement in safety if these countermeasures were applied retrospectively meant a reduction of 4,634 injury crashes and 1,555 casualties over the 12-year period with an estimated cost saving of approximately £368 million or 2.7 billion Dirhams. To refine this method more detailed data on crashes were required and collected from the dedicated crash investigation team files in Dubai Police for 2006 and part of 2007. This new dataset (300 crashes) was put into a purpose-built database with over 140 fields and subject to microanalysis to more accurately match the problems and interventions. Six interventions were matched to individual cases in the database where they would have positively altered the outcome. This process was verified by independent crash experts and investigators. The benefits from these six countermeasures were then weighted to calculate the benefits for the whole crash population over a year. Examples of specific interventions included guardrails along the roadside; grade-separated crossing facilities for pedestrians; Electronic Stability Control and speed cameras. The estimated total reduction in crashes was 2,412 annually with calculated savings of £40 million or 280 million Dirhams. This was the first time this geographical area was studied in such depth and detail to allow the calculation of benefits from interventions matched to known road safety issues. Various limitations were encountered such as the unavailability of GIS basemaps and the continuously changing infrastructure and population of Dubai. Numerous areas of further work were identified. Such work areas include hospital studies for collecting injury data to compare with police data; changing vehicle standards so that they are better suited to local crash types; the calculation of crash and injury costs based on local figures; vehicle fleet analysis for comparing different vehicle segments and exposure; and improved data collection and storage methods.

Master of Science / Department of Civil Engineering / Sunanda Dissanayake / In order to improve safety of the overall surface transportation system, each of the critical areas needs to be addressed separately with more focused attention. Statistics clearly show that large-truck crashes contribute significantly to an increased percentage of high-severity crashes. It is therefore important for the highway safety community to identify characteristics and contributory causes related to large-truck crashes. During the first phase of this study, fatal crash data from the Fatality Analysis Reporting System (FARS) database were studied to achieve that objective. In this second phase, truck-crashes of all severity levels were analyzed with the intention of understanding characteristics and contributory causes, and identifying factors contributing to increased severity of truck-crashes, which could not be achieved by analyzing fatal crashes alone. Various statistical methodologies such as cross-classification analysis and severity models were developed using Kansas crash data. Various driver-, road-, environment- and vehicle- related characteristics were identified and contributory causes were analyzed. From the cross-classification analysis, severity of truck-crashes was found to be related with variables such as road surface (type, character and condition), accident class, collision type, driver- and environment-related contributory causes, traffic-control type, truck-maneuver, crash location, speed limit, light and weather conditions, time of day, functional class, lane class, and Average Annual Daily Traffic (AADT). Other variables such as age of truck driver, day of the week, gender of truck-driver, pedestrian- and truck-related contributory causes were found to have no relationship with crash severity of large trucks. Furthermore, driver-related contributory causes were found to be more common than any other type of contributory cause for the occurrence of truck-crashes. Failing to give time and attention, being too fast for existing conditions, and failing to yield right of way were the most dominant truck-driver-related contributory causes, among many others. Through the severity modeling, factors such as truck-driver-related contributory cause, accident class, manner of collision, truck-driver under the influence of alcohol, truck maneuver, traffic control device, surface condition, truck-driver being too fast for existing conditions, truck-driver being trapped, damage to the truck, light conditions, etc. were found to be significantly related with increased severity of truck-crashes. Truck-driver being trapped had the highest odds of contributing to a more severe crash with a value of 82.81 followed by the collision resulting in damage to the truck, which had 3.05 times higher odds of increasing the severity of truck-crashes. Truck-driver under the influence of alcohol had 2.66 times higher odds of contributing to a more severe crash. Besides traditional practices like providing adequate traffic signs, ensuring proper lane markings, provision of rumble strips and elevated medians, use of technology to develop and implement intelligent countermeasures were recommended. These include Automated Truck Rollover Warning System to mitigate truck-crashes involving rollovers, Lane Drift Warning Systems (LDWS) to prevent run-off-road collisions, Speed Limiters (SLs) to control the speed of the truck, connecting vehicle technologies like Vehicle-to-Vehicle (V2V) integration system to prevent head-on collisions etc., among many others. Proper development and implementation of these countermeasures in a cost effective manner will help mitigate the number and severity of truck-crashes, thereby improving the overall safety of the transportation system.

The St. Charles streetcar is an important transit line in the city of New Orleans, with about 65,000 people living within a ½ mile walking distance from it. However, the line experiences a very high streetcar/automobile crash rate due in large part to the large number of grade vehicle crossings over the tracks that lack signalization. Through traffic modeling, the closure of many of these vehicle crossings and the diversion of automotive traffic to the remaining, signalized crossings is analyzed to determine traffic impacts on street network. The result is a modest increase in traffic, about 7-8%, at the remaining signalized intersections.

<p>Syftet med uppsatsen är att undersöka, jämföra och diskutera eventuella faktorer till varför det har skett en så kraftig ökning av helikopterhaverier under de senaste tio åren jämfört med stridsflygshaverier. Problemet belyses och analyseras utefter ett MTO- perspektiv (människa, teknik och organisation). Stor vikt i uppsatsen läggs på de haverirapporter som är en följd av haverier mellan 1997 – 2007. Organisationsförändringar, flygmaskiner och utbildning är exempel på några andra delar som också behandlas. Viktigaste slutsatserna med uppsatsen är att helikopterhaverierna till stor del berott på den mänskliga faktorn medan stridsflyget har haft mer varierande orsaker. Faktorer som kan ha påverkat så att helikopterhaverierna har ökat jämfört med stridsflygshaverierna är följande tre.- Sammanslagningen av armeflyget, marinflyget och helikopterverksamheten i Flygvapnet.- Att flygning med helikopter i större omfattning sker på låg höjd.- Fler personer i en besättning kan påverka flygningen.</p> / <p>The purpose of this essay is to investigate, compare and discuss possible factors that have contributedto the big increase in helicopter crashes in the last ten years compared to fighter jets. The problem is looked upon and analyzed from an HTO perspective (human, technology and organisation). A lot of the essay is focused on the investigation reports that has followed all crashes between 1997-2007. Organisational change, different aircrafts and education and training are examples of other factorsthat are discussed in the essay. The most important conclusions that have been drawn are that helicopter crashes are mostly due to human factors reasons. Fighter jet crashes have more variation in the causes. Factors that may have been contributing in increasing helicopter crashes compared to fighter jets are:- The fusion between the army, marine and air force helicopter units- Helicopter flying is more frequently done on a lower altitude- There are more people part of the helicopter crew which can affect the flight</p>

Syftet med uppsatsen är att undersöka, jämföra och diskutera eventuella faktorer till varför det har skett en så kraftig ökning av helikopterhaverier under de senaste tio åren jämfört med stridsflygshaverier. Problemet belyses och analyseras utefter ett MTO- perspektiv (människa, teknik och organisation). Stor vikt i uppsatsen läggs på de haverirapporter som är en följd av haverier mellan 1997 – 2007. Organisationsförändringar, flygmaskiner och utbildning är exempel på några andra delar som också behandlas. Viktigaste slutsatserna med uppsatsen är att helikopterhaverierna till stor del berott på den mänskliga faktorn medan stridsflyget har haft mer varierande orsaker. Faktorer som kan ha påverkat så att helikopterhaverierna har ökat jämfört med stridsflygshaverierna är följande tre.- Sammanslagningen av armeflyget, marinflyget och helikopterverksamheten i Flygvapnet.- Att flygning med helikopter i större omfattning sker på låg höjd.- Fler personer i en besättning kan påverka flygningen. / The purpose of this essay is to investigate, compare and discuss possible factors that have contributedto the big increase in helicopter crashes in the last ten years compared to fighter jets. The problem is looked upon and analyzed from an HTO perspective (human, technology and organisation). A lot of the essay is focused on the investigation reports that has followed all crashes between 1997-2007. Organisational change, different aircrafts and education and training are examples of other factorsthat are discussed in the essay. The most important conclusions that have been drawn are that helicopter crashes are mostly due to human factors reasons. Fighter jet crashes have more variation in the causes. Factors that may have been contributing in increasing helicopter crashes compared to fighter jets are:- The fusion between the army, marine and air force helicopter units- Helicopter flying is more frequently done on a lower altitude- There are more people part of the helicopter crew which can affect the flight