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Although cruise control (CC) is available for most cars, no studies have been found which examine how this automation system influences driving behaviour. However, a relatively large number of studies have examined adaptive cruise control (ACC) which compared to CC includes also a distance control. Besides positive effects with regard to a better compliance to speed limits, there are also indications of smaller distances to lead vehicles and slower responses in situations that require immediate braking. Similar effects can be expected for CC as this system takes over longitudinal control as well. To test this hypothesis, a simulator study was conducted at the German Aerospace Center. Twenty-two participants drove different routes (highway and motorway) under three different conditions (assisted by ACC, CC and manual driving without any system). Different driving scenarios were examined including a secondary task condition. On the one hand, both systems lead to lower maximum velocities and less speed limit violations. There was no indication that drivers shift more of their attention towards secondary tasks when driving with CC or ACC. However, there were delayed driver reactions in critical situations, e.g., in a narrow curve or a fog bank. These results give rise to some caution regarding the safety effects of these systems, especially if in the future their range of functionality (e.g., ACC Stop-and-Go) is further increased.
Knowledge of material properties is of great importance when developing new types of concrete and construction methods for road building, and for quality control and quality assurance. Physical material characteristics are likewise the basis for dimensioning and assessing the residual substance of concrete pavements. One relevant characteristic when examining thermally induced stress and deformation is the coefficient of thermal expansion (CTE) of concrete. This indicator, for example, significantly influences the longitudinal expansion of the pavement system as well as the degree of curling of slabs and joint movements. Extensive tests were conducted during the technical engineering assessment of the structural substance of concrete pavements in the German motorway network, including tests to determine the CTE of existing types of concrete. Because no standardised procedure currently exists in Germany for using tests to determine the CTE of concrete, the initial task was to develop a suitable test procedure from a road-building perspective, taking consideration of the national prevailing structural conditions. This article presents the results of selected status analyses, in which the CTE was determined for a total of 656 individual samples. The values calculated for the top and bottom drilled core layer are in the range 8.9 – 13.2 x 10-6/K, whereby the average CTE assumes a value of 10.7 x 10-6/K. The deviations of the CTEs from the bottom and top drilled core layer are in principle significantly below the limitation to a maximum of 2.50 x 10-6/K recommended in literature.
The Intersection 2020 project was initiated to develop a test procedure for Automatic Emergency Braking systems in intersection car-to-car scenarios to be transferred to Euro NCAP. The project aims to address current road traffic accidents on European roads and therefore sets a priority of the identification of the most important car-to-car accidents and Use Cases. Taking into account technological and practical limitations, Test Scenarios are derived from the Use Cases in a later stage of the project. This paper presents parts of a larger study and provides an overview of common car-to-vehicle(at least four wheels) collision types at junctions in Europe and specifies seven Accident Scenarios from which the three scenarios “Straight Crossing Paths (SCP)”, “Left Turn Across Path – Opposite Direction Conflict (LTAP/OD)” and “Left Turn Across Path – Lateral Direction (LTAP/LD)” are most important due to their high relevance regarding severe car-to-car accidents. Technical details about crash parameters such as collision and initial speeds are delivered. The analysis work performed is input for the definition and selection of the Use Cases as well as for the project’s benefit estimation. The numbers of accidents and fatalities in accidents at intersections involving a passenger car were shown per intersection type. In both statistics, it was found that accidents at crossroads and T- or staggered junctions are of highest relevance, followed by roundabouts. Focusing on accidents at intersections between one passenger car and another road user shows that around one-third of all accidents and related fatalities could have been assigned to car-to-PTW accidents and one-fifth of all accidents and fatalities to car-to-car accidents. Regarding car-to-car accidents with at least serious injury outcome 38% out of 34,489 car-to-car accidents happened at intersections. These figures correspond to 18% of the fatalities (4,236 fatalities in total). Considering all intersection types, around half of all related accidents happened in urban environments whereas this number decreased to one-third of all fatalities. Further, the proportion of road fatalities per country occurring at intersections varies widely across the EU. Also, there are proportionately more fatalities in daylight or twilight conditions at junctions. Use Cases are supposed to be derived from Accident Scenarios and by adding detailed information for example about the road layout, right-of-way and the vehicle trajectories prior to the collision. Instead of applying cluster algorithms to the accident data, a pragmatic approach was finally preferred to create them. Note: Use Cases serve as an intermediate step between the Accident Scenarios and the Test Scenarios which describe the actual testing conditions. Finally, 74 Use Cases were identified. This large number indicates the complexity of intersection crashes due to the combination of several parameters.
Topics of the status report are: Road accidents in Germany ; Socio-economic costs due to road traffic accidents in Germany , German Road Safety Programme. Finished projects: Turning Assist Systems for Trucks ; Handbook „Accessibility in long-distance bus transport“ ; EU project PROSPECT ; Intersection assistance (Euro NCAP) ; Personal Light Electric Vehicles (PLEV) ; Automatic Emergency Braking for Heavy Goods Vehicles ; KO-HAF ; AFAS ; SENIORS ; Adoption of UN-GTR9-PH2. Ongoing and planned research: Safety potential and testing of reversing assistants for passengers cars (M1) and LGV´s (N1) ; Study on winter tires ; Automatic Emergency Braking for passenger cars ; Motorcyclist-friendly safety barriers ; Active motorcycle safety ; EU-Project PIONEERS ; Friction prediction ; Bus safety: smoke gas toxicity ; HMI aspects on Camera-Monitor-Systems ; Activities with regard to UN R 22 and helmets for S-Pedelecs ; Seriously injured road accident casualties ; UNECE IWG on Deployable Pedestrian Protection Systems (Active bonnets) ; GIDAS – new requirements to address new vehicle technology ; Human Body Modelling ; Child Safety at the UNECE with regard to R 129 ; Development of requirements on automated driving functions for vehicle regulations ; EU-Project L3-Pilot ; Development of evaluation methods for driver interaction with assistance and automation (national research and Euro NCAP) ; EU-Project OSCCAR ; PEGASUS ; Development of basic scenarios for the description of control-relevant requirements for continuous automated vehicle guidance ; EU project HEADSTART ; C-Roads Germany ; Practical Test for the Quality of Congestion-Tail Information ; Research program road safety.
Per definition, SAE Level 2 (L2) Systems perform both the lateral and longitudinal vehicle motion control with the expectation that the driver completes the Object and Event Detection and Response (OEDR). Since every system performs also parts of the OEDR itself and this amount of OEDR also varies between different L2 systems depending on the intended system design, it cannot be taken for granted that drivers automatically understand their roles and responsibilities in interaction with the system. Especially highly reliable L2 systems performing a greater amount of OEDR while at the same time requiring only little driver input over time can make it difficult for drivers to correctly identify their role and responsibility. Until now, neither application-oriented assessment methods nor design guidelines for OEDR related system design features taking safety of human-machine-interaction into account are available. The objective is therefore to deliver a standardized tool for the assessment of human-machine-interaction-related safety of vehicles with L2 systems currently available on the market. To evaluate the impact of different system design aspects on safety of human-machine-interaction and also to be able to differentiate between system designs, a holistic, standardized and application-oriented assessment procedure is proposed. The novel tablet-based assessment tool focuses not only on available standards and guidelines but measures also concrete user behaviour and user understanding in interaction with the L2 systems. The aim is to gain further insights which cannot be measured directly by simple checklist instruments. For preparation, based on international standards, literature reviews and expert consultations, a first checklistbased expert-evaluation for currently available vehicles with L2 systems was developed. These assessments are focusing on different sources of user information (e.g. user manual), human-machine-interface design as well as the prevention of unintended use by different driver monitoring techniques. The checklist-tool was developed in cooperation with experts of different EuroNCAP test laboratories and validated in a common expert workshop to gain high level of standardization and agreement. However, to assess safety of human-machine-interaction holistically beyond these rather explicit forms of information design criteria, also implicit forms of drivervehicle-communication via vehicle dynamics, functional behavior or reliability play an important role and should be taken into account. Therefore, the main and novel methodological aim is to consider also interaction related processes regarding user´s understanding of roles and responsibilities when applying automated driving functions as well as user´s awareness of automation modes or traffic situations in the modular tablet-based assessment tool.
Airbags are, together with the three-point belt, the most effective passive safety equipment of vehicles. However, literature shows that sound pressure levels of up to 170 dB can occur during airbag deployment. A literature review revealed no systematic experimental data on possible hearing loss by airbag deployment, that also takes any other crash accompanied noise into account, such as deformation and impact noise. Also the rising number of airbags per vehicle resulting in a higher number of deployed airbags in an accident was not addressed with respect to hearing loss. Thus, an extensive test matrix of noise measurements during airbag deployments was conducted including onboard measuring during crashes and static measurements. Dynamic and static experiments with single and multiple airbag deployments were conducted. The results of this study show, that in the analyzed crash constellations the acoustic emission of the collision as well as the car deformation can trigger the stapedius reflex before the airbag deployment. The stapedius reflex protects the inner ear at least partially in case of dangerous sound levels. However, it seems that multiple airbag deployments in a short sequence pose a considerable risk for hearing impairments despite the fully contracted stapedius muscle. Further and in line with Price et al. (2013) it was found that the risk of hearing loss is lower with closed windows. The analysis of patient and accident data showed no link between airbag deployment and hearing loss. This might be caused by low case numbers of reported hearing loss problems up to now. In conclusion the results show that a singular analysis of the sound pressure of airbag deployments without crash accompanied noises is not sufficient as the protective effect of the stapedius reflex is neglected. Still, successive airbag deployments in a short timeframe raise the risk of hearing loss. Further investigation on hearing impairment due to airbag deployment and triggering of the stapedius reflex is needed and the data acquisition of accidents and patients should consider hearing loss aspects.
Bicyclists and pedestrians belong to the most endangered groups in urban traffic. The EU-funded collaborative research project PROSPECT (‘PROactive Safety for PEdestrians and CyclisTs´) aims to significantly improve safety of those unprotected traffic participants by expanding the scope of scenarios covered by future active safety systems in passenger cars. Concepts for sensor control systems are built into three prototypes covering emergency interventions such as Autonomous Emergency Braking (AEB) as well as Autonomous Emergency Steering (AES). These systems tackle the well-known challenges of currently available systems including limited field-of-view by sensors, fuzzy path prediction, unreliable intent reaction times and slow reaction times. These highly innovative functions call for extensive validation methodologies based on already established consumer testing procedures. Since these functions are developed towards the prevention of intersection accidents in urban areas, a key aspect of the advanced testing methodology is the valid approximation of naturalistic trajectories using driving robots. Eventually, several simulator studies complemented a user acceptance and benefit analysis to evaluate the expected overall impact of the PROSPECT systems. The results achieved within the PROSPECT project are highly relevant for upcoming test protocols regarding the most critical situations with Vulnerable Road Users (VRU). With introducing the new methods in Euro NCAP (European New Car Assessment Programme) a significant increase in road safety is expected.
Effects of time pressure on left-turn decisions of elderly drivers in a fixed-base driving simulator
(2019)
In countries with right lane traffic left-turn maneuvers at intersections are known to be particularly critical for elderly drivers. It has been suggested that the implementation and use of Advanced Driver Assistance Systems (ADAS) might offer a solution to compensate for age-related weaknesses in driving-related skills. In the present paper an experiment is reported which explored the effects of time pressure on the performance of left-turn manoeuvers supported by an ADAS function (time gap assistant). The study was performed in a fixed-base driving simulator with 20 younger (22-37) and 21 elderly drivers (60-84) who were observed when negotiating left-turn manoeuvers on rural roads with and without the assistance function active. Subjects performed the task once under conditions of time pressure once without. Results indicate that both age groups used the assistance function to perform the left-turn manoeuvers with shorter time gaps. Under conditions of time pressure this effect was more pronounced, and the effects of time pressure were stronger for the elderly. However, there were only weak indications for a specific benefit of the assistance function for the elderly.
Test and assessment procedures for passive pedestrian protection of passenger cars are in place for many years within world-wide regulations as well as consumer test programmes. Nevertheless, recent accident investigations show a stagnation of pedestrian fatality numbers on European roads alongside increasing injury severities for older road users. The EU-funded SENIORS (Safety ENhancing Innovations for Older Road userS) project developed and evaluated a thorax injury prediction tool (TIPT) for later incorporation within test and assessment procedures. Accident data indicates an increasing portion of AIS2 and AIS3+ thoracic injuries of older pedestrians and cyclists which are currently not assessed in any test procedure for vulnerable road users. Therefore, SENIORS focused on the development of a test tool predicting the risk of rib fractures of vulnerable road users (VRU). While injury risk functions were reanalyzed, human body model (HBM) simulations against categorized generic vehicle frontends served as input for the definition of test setups and corresponding impact parameters. TIPT component tests against a generic frontend and an actual vehicle were used for the evaluation of the technical feasibility. The TIPT component tests shows the general feasibility of a test procedure for the assessment of thoracic injuries, with good repeatability and reproducibility of kinematics and results. Impact parameters such as the inclination angles of the thorax, angles of the velocity vector and impact speeds well replicate the parameters gained from the HBM simulations. The proposed markup and assessment scheme offers the possibility of a homogeneous evaluation of the protection potential of vehicle frontends while maintaining justifiable testing efforts. During evaluation testing, the proposed requirements were entirely met. The developed prototype of TIPT and launching system offer impact angles and speeds as suggested by HBM simulations. However, since thorax impacts during pedestrian accidents do not occur perpendicularly to the vehicle surface in most cases, the TIPT built-in linear potentiometers do not acquire the true resultant intrusions on the ribcage and thus, TIPT rib deflections do not reflect the actual human injury risk. However; for the impact forward to the bonnet leading edge, the TIPT seems applicable without further modifications. The test and assessment procedures using the TIPT offer for the first time the possibility of replicating the kinematics of a pedestrian thorax with a component test. The developed assessment scheme gives a first indication on how the risk for thoracic injuries could be implemented within the Euro NCAP Box 3 assessment. Future development of the TIPT may focus on implementing a rib cage that can deflect in all axes in a humanlike way.
APT with the mobile load simulator MLS10 towards non-destructive pavement structural analysis
(2019)
In 2014 a research program has been started about non-destructive test methods to evaluate the structure of pavements. This task has been given to two research groups - first research group is led by RWTH Aachen University (Rheinisch-Westfälische Technische Hochschule) and the second by University of Siegen. This paper focuses on the initial findings of the running research program. The assessment of the existing infrastructure and its condition will be one of the main tasks during the next years in order to use the available budget for maintenance accurately and efficiently. Therefore, it is necessary to identify possible damages and examine their effects on the road construction. BASt (Federal Highway Research Institute) is using the Mobile Load Simulator MLS10 for accelerated pavement testing (APT) on different types of pavements. In addition to non-destructive test methods, sensors are applied to measure structural impacts. The overall objective of this research program is to develop a non-destructive test method that allows the calculation of the remaining life time and load cycles of pavements. To simulate realistic wheel loads in a short period of time the MLS10 on German full scale standard pavement constructions has been used. The first pavement test section was loaded with 3 x 10 high 6 50 kN wheel loads while the second, thinner pavement test section was loaded with 3 x 10 high 5 50 kN wheel loads. Both loads are equivalent to the pavement design load. Three different strategies have been used to analyze and monitor structural changes. The innovative measurements have been realized by the two research groups to collect data for their models. The RWTH Aachen collected data with twelve geophones aligned in a row parallel to the wheel path. The geophones measure the entire vertical deflection basin of the pavement surface that exists due to the passing real truck wheels. These measurements were done for different truck speeds and at different transverse distances to the wheel path. The University of Siegen collected data by using acceleration sensors on the surface of the road construction. After recording the data they were integrated into displacement signals and evaluated. Additionally to those measurements BASt used conventional equipment to monitor the pavement structure and surface characteristics. The measurements and evaluation tools used for the innovation program have a high potential to validate APT programs in the future. Based on this research it is possible to start further research activities to push the non-destructive evaluation of pavements structures - not only in APT - into an improved direction.