One of the principal energy absorbing structural components that influences the crashworthiness of a vehicle is the side-rail, which is also commonly referred to as an s-rail due to its shape that is reminiscent of an “s”. To improve the crashworthiness of a vehicle, in the wake of significant environmental pressures requiring vehicle light-weighting, the parameters that govern the crash response of the s-rail and the implications of light-weight material substitution need to be better understood. In this work, the main parameters that govern the crash response of an s-rail and the variables that influence them were identified and assessed through a combined experimental and numerical modelling programme. In particular, the as-formed properties of aluminium alloy s-rails, due to the tube bending and hydroforming fabrication route were examined. Tube bending, hydroforming and crash experiments were conducted to examine and assess the effects of initial tube thickness, strength, geometry, bend severity, work hardening, thickness changes and residual stresses on the crash response of the s-rail. The forming process variables, springback, thickness, strains, and force and energy response measured in the experiments were used to validate the finite element models developed herein. The validated numerical models of tube bending, hydroforming and crash provided additional insight and also allowed further investigation of the parameters governing the crash response of s-rails. The relevant parameters governing the crash response of s-rails were isolated and the basis for a set of design guidelines, in terms of maximizing energy absorption or minimizing mass, was established. The overall size is the most influential design parameter affecting the energy absorption capability of the s-rail, followed by the initial thickness, material strength, cross-sectional geometry, bend severity and hydroforming process employed, and finally boost in bending. The most significant conclusion made based on this research is that the effects of forming history must be considered to accurately predict the crash response of the s-rail. There are additional conclusions with respect to the tube bending and hydroforming processes, as well as s-rail crash response, that will contribute to improving the design of s-rails for better crashworthiness of vehicles.

In this thesis the sheet metal forming effects such as plastic strain and thickness changes in the crash have been investigated by numerical analysis. The sheet metal forming histories of the components of the load path that absorbs the highest energy during a frontal crash have been considered. To find out the particular load path, the frontal crash analysis of Ford F250 Pickup has been performed at 56 kph into a rigid wall with finite element analysis without considering the forming history. The sheet metal forming simulations have been realized for each structural component building up the particular load path. After forming histories have been acquired, plastic strain and thickness distributions have been transferred to the frontal crash analysis. The frontal crash analysis of Ford F250 Pickup has been repeated by including these to introduce the effect of forming on crash response of the vehicle. The results of the simulations with and without forming effect have been compared with the physical crash test results to evaluate the sheet metal forming effect on the overall crash response. The results showed that with forming history the crash response of the vehicle and deformations of the particular components have been changed and the maximum deceleration pulse transferred to the passenger compartment has decreased. It has seen that a good agreement with physical test results has been achieved.

Die vorliegende Arbeit leistet einen Beitrag zur Identifizierung von Einflussgrößen und Fehlerursachen auf Verkehrsunfälle. Diese können als Grundlage für Hinweise für den Einsatz und die Gestaltung von Fahrerassistenzsystemen genutzt werden. Dafür wurden insgesamt 506 Unfälle umfassend (in depth) untersucht. Zur Analyse der Pre-Crash-Phase der Unfälle wurden die Ergebnisse einer psychologischen Befragung mit Angaben aus der polizeilichen Verkehrsunfallanzeige, Informationen zur Unfallstelle, medizinischen Berichten sowie Informationen aus der technischen Rekonstruktion integriert. Anschließend wurde eine Fehleranalyse unter Betrachtung der Teilsysteme Fahrer, Umwelt und Fahrzeug durchgeführt. Um den bestmöglichen Befragungszeitpunkt herauszufinden, wurden in einer Vorstudie jeweils 15 Interviews am Unfallort sowie telefonische Interviews ein bis 14 Tage bzw. 15 bis 90 Tage nach dem Unfall bezüglich der Anzahl ihrer Genauigkeits- und Glaubhaftigkeitsmerkmale, der Motivation zur Interviewteilnahme sowie möglicher Vergessenseffekte verglichen. Im Ergebnis konnten keine Nachteile nachträglicher telefonischer Befragungen im Vergleich zu Befragungen an der Unfallstelle gefunden werden. Zur Fehleranalyse wurde ein verkehrspsychologisches Fehlerklassifikationsschema auf der Basis der verhütungsbezogenen Klassifikation von Fehlhandlungsursachen (Hacker, 1998) erstellt. Mit dessen Hilfe wurden insgesamt 696 Unfalleinflussfaktoren für die Unfallverursacher (n=343) ermittelt. Im Ergebnis wurde so bei allen Unfalltypengruppen ein hoher Anteil von Fehlern infolge von Ablenkung sowie Aktivierungsmängeln festgestellt (jeweils zwischen 28 % und 47%). Des Weiteren gab es bei Kreuzungsunfällen zahlreiche Fehler infolge von Sichtverdeckungen (40%), Fokusfehlern (30%), Reizmaskierungen (26%) und Verstößen gen die Verkehrsregeln (11%). Unfälle durch Abkommen von der Fahrbahn traten zudem häufig infolge von Erwartungsfehlern (35%), Reizmaskierungen (26%), Verstößen gegen die Verkehrsregeln (24%) sowie Zielsetzungs- bzw. Handlungsfehler (23%) auf. Unfälle im Längsverkehr passierten des Weiteren durch Erwartungsfehler (36%), Zielsetzungs- und Handlungsfehler (36%) sowie durch Setzen eines falschen Aufmerksamkeitsfokus (24%) auf. Anhand dieser Studienergebnisse ist das Sicherheitspotential für Fahrerassistenzsysteme, welche den Fahrer bei der Informationsaufnahme unterstützen und ihm helfen Ablenkungen und Aktivierungsdefizite zu vermeiden, als hoch einzuschätzen. So könnten insgesamt über zwei Drittel der erfassten Fehlhandlungen vermieden werden. Darüber hinaus münden die Studienergebnisse in ein Klassifikationsschema zur Erfassung von Unfalleinflussfaktoren, welches im Rahmen der Unfallforschung dauerhaft eingesetzt werden sollte.

This thesis deals with documentation and analysis of the most common types of vehicle damage caused by collisions with fixed objects at low speeds. The characteristic damage analysis is based on performing custom crash tests using objects that are different in shape and material. Furthermore, the thesis deals with the comparison of performed crash tests with vehicle damage typical for collisions of two vehicles in so-called parking maneuvres. The analysis is then applied in the assessment of real traffic accidents, which were identified as insurance frauds during the investigation. The work can be further used as a basis for comparative databases.

This thesis is devoted to the design model of the lower limbs crash test dummies. It describes how the dummy developed historically, what are currently available for crash tests, what they are made and what their future will be. The main motive of the work is to design a model of lower limb for crash tests, with emphasis on the human anatomy. The work is characterized by how the figurine is produced using the form from material Thermolyne Clear, wood as a substitute human bones and the agar substitutes such as human muscle.

Physical inactivity increases the risk of multiple diseases with extensive personal and societal effects [1]. For instance, the annual economic cost of physical inactivity is estimated to be more than 80 billion euros in the European Union (EU) [2]. One measure to increase physical activity is the promotion of active transport modes, such as cycling. Finland is aiming to increase the mode share of active transport modes to 35-38% by 2030 [3]. In tbe most recent national travel survey 8% of daily trips were made by bicycle and 22% of daily trips involved walking [ 4]. A shift from cars to more sustainable transport modes is desirable, however more work is needed to promote cycling safety, with cyclists over-represented in fatal (11%) and serious injuries (32%) when compared to mode share [5]. Amongst cyclist crashes in Finland, single-bicycle crashes (SBCs), where other road users are not collided with, represent more than half of non-fatal injuries [6-7] and 46% of fatal injuries [8--9]. This proportion of non-fatal injuries is similar to findings from other jurisdictions [6]. However, the rate of fatal injuries in SBCs is substantially higher in Finland compared to the average rate in Europe [10], highlighting the importance of understanding SBCs in a Finnish context. Analyses of SBCs are usually more challenging than crashes between bicycles and motor vehicles because SBCs are typically underreported in police-reported crash data [11]. However, in Finland, road crash investigation teams investigate almost all fatal road crashes, including SBCs. This captures high-quality information on SBCs including their contributory and background risk factors, as well as safety recommendations. Identifying the contributory factors that enable the occurrence of crashes and implementing actions to prevent these crashes can help promote cycling safety [ 12]. Such analyses and actions are particularly needed in Finland, where there are targets to increase the mode share of cycling. Given the robust data available through the in-depth investigations undertaken in Finland, this study aims to increase knowledge on SBCs and their safety recommendations by analysing data on fatal cycling crashes in Finland. The study compares the key characteristics, risk factors and safety recommendations regarding SBCs and other cyclist crashes. Although the data for this study is sourced from Finland, the findings are useful in other countries with similar bicycle infrastructure and weather conditions. [From: Introduction]

As a result of high crash frequencies on roadways, transportation safety has become a high priority for the United States Department of Transportation and the Utah Department of Transportation. A large percentage of fatal and injury crashes on roadways occur at intersections and traffic signals have been implemented to reduce these severe crashes. There is a need to evaluate the effectiveness of the traffic signal improvements through the development of Crash Modification Factors (CMFs). Recent research has shown that traditional safety evaluation methods have been inadequate in developing CMFs. In recent years, Bayesian statistical methods have been utilized in traffic safety studies to more accurately analyze the effectiveness of safety improvements. The hierarchical Bayesian method is an advanced statistical technique that has the capability to account for the shortcomings of traditional methods and to more fully reflect the effectiveness of safety improvements. This report uses a hierarchical Bayesian model to analyze the effectiveness of new traffic signal installations and modified traffic signals. CMFs were developed for multiple scenarios for both new and modified traffic signals. A benefit-to-cost (B/C) analysis was also performed for each improvement to determine how long it would take to recover the cost of installation. The results showed that there was an increase in overall crashes for both new signal installations and modifications to existing signals. The severe crash analysis revealed that there was an increase in non-severe crashes and a reduction in severe crashes; the improvements are effectively reducing severe crashes and improving safety at intersections. The B/C analyses indicate that there is a safety benefit to both improvements and that new signal installation costs can be recovered in approximately 5 years while the installation of a left-turn signal modification can be recovered in approximately 9 weeks.

This research evaluates Intelligent Transportation System (ITS) implementation strategies to improve the safety of a freeway once a potential of a crash is detected. Among these strategies are Variable Speed Limit (VSL) and ramp metering. VSL are ITS devices that are commonly used to calm traffic in an attempt to relieve congestion and enhance throughput. With proper use, VSL can be more cost effective than adding more lanes. In addition to maximizing the capacity of a roadway, a different aspect of VSL can be realized by the potential of improving traffic safety. Through the use of multiple microscopic traffic simulations, best practices can be determined, and a final recommendation can be made. Ramp metering is a method to control the amount of traffic flow entering from on-ramps to achieve a better efficiency of the freeway. It can also have a potential benefit in improving the safety of the freeway. This thesis pursues the goal of a best-case implementation of VSL. Two loading scenarios, a fully loaded case (90% of ramp maximums) and an off-peak loading case (60% of ramp maximums), at multiple stations with multiple implementation methods are strategically attempted until a best-case implementation is found. The final recommendation for the off-peak loading is a 15 mph speed reduction for 2 miles upstream and a 15 mph increase in speed for the 2 miles downstream of the detector that shows a high crash potential. The speed change is to be implemented in 5 mph increments every 10 minutes. The recommended case is found to reduce relative crash potential from .065 to -.292, as measured by a high-speed crash prediction algorithm (Abdel-Aty et al. 2005). A possibility of crash migration to downstream and upstream locations was observed, however, the safety and efficiency benefits far outweigh the crash migration potential. No final recommendation is made for the use of VSL in the fully loaded case (low-speed case); however, ramp metering indicated a promising potential for safety improvement.

Since its inception in 1965, the Level-of-Service (LOS) has proved to be an important and practical "quality of service" indicator for transportation facilities around the world, widely used in the transportation and planning fields. The LOS rates these facilities' traffic operating conditions through the following delay-based indicators (ordered from best to worst conditions): A, B, C, D, E and F. This LOS rating has its foundation on quantifiable measures of effectiveness (MOEs) and on road users' perceptions; altogether, these measures define a LOS based on acceptable traffic operating conditions for the road user, implying that traffic safety is inherent to this definition. However, since 1994 safety has been excluded from the LOS definition since it cannot be quantified nor explicitly defined. The latter has been the motivation for research based on the LOS-Safety relationship, conducted at the University of Central Florida (UCF). Using data from two of the most studied transportation facility types within the field of traffic safety, signalized intersections and multilane high-speed arterial corridors, the research conducted has the following main objectives: to incorporate the LOS as a parameter in several traffic safety models, to extend the methodology adopted in previous studies to the subject matter, and to provide a platform for future transportation-related research on the LOS-Safety relationship. A meticulous data collection and preparation process was performed for the two LOS-Safety studies comprising this research. Apart from signalized intersections' and multilane-high speed arterial corridors' data, the other required types of information corresponded to crashes and road features, both obtained from FDOT's respective databases. In addition, the Highway Capacity Software (HCS) and the ArcGIS software package were extensively used for the data preparation. The result was a representative and robust dataset for each LOS-Safety study, to be later tested and analyzed with appropriate statistical methods. Regarding the LOS-Safety study for signalized intersections, two statistical techniques were used. The Generalized Estimating Equations (GEEs), the first technique, was used for the analyses considering all periods of a regular weekday (i.e. Monday through Friday): Early Morning, A.M. Peak, Midday, P.M. Peak and Late Evening; the second technique considered was the Negative Binomial, which was used for performing an individual analysis per period of the day. On the other hand, the LOS-Safety study for multilane high-speed arterial corridors made exclusive use of the Negative Binomial technique. An appropriate variable selection process was required for the respective model building and calibration procedures; the resulting models were built upon the six following response variables: total crashes, severe crashes, as well as rear-end, sideswipe, head-on and angle plus left-turn crashes. The final results proved to be meaningful for the understanding of traffic congestion effects on road safety, and on how they could be useful within the transportation planning scope. Overall, it was found that the risk for crash occurrence at signalized intersections and multilane high-speed arterial corridors is quite high between stable and unacceptable operating conditions; it was also found that this risk increases as it becomes later in the day. Among the significant factors within the signalized intersection-related models were LOS for the intersection as a whole, cycle length, lighting conditions, land use, traffic volume (major and minor roads), left-turn traffic volume (major road only), posted speed limit (major and minor roads), total number of through lanes (major and minor roads), overall total and total number of left-turn lanes (major road only), as well as county and period of the day (dummy variables). For multilane-high speed arterial corridors, the final models included LOS for the road section, average daily traffic (ADT), total number of through lanes in a single direction, total length of the road section, pavement surface type, as well as median and inside shoulder widths. A summary of the overall results per study, model implications and each LOS indicator is presented. Some of the final recommendations are to develop models for other crash types, to perform a LOS-Safety analysis at the approach-level for signalized intersections, as well as one that incorporates intersections within the arterial corridors' framework.

No description available.