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  • Kristoffersson, Ida
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Berglund, Svante
    WSP.
    Algers, Staffan
    KTH.
    Estimation of large-scale tour generation model taking travellers' daily tour pattern into account2019Report (Other academic)
    Abstract [en]

    Tour generation is conventionally modelled separately per tour purpose. Tours with different purposes are however not generated independently of each other in reality. For example, few travellers conduct more than three tours per day. In this paper, the conventional tour generation model is extended into estimation of a model that takes travellers’ daily tour pattern into account. Results show that access to car and drivers’ licence, having a job and presence of children in the household increase the probability of making many tours in one day. Furthermore, results show that accessibility is an important factor for generation of non-mandatory tours, that weekend and holiday season are important determinants of when tour purposes are generated, that high income increases the probability of conducting business tours as well as tour patterns that include expensive activities and that high income reduces the probability of conducting cheap activities such as visiting friends and family.

  • Asplund, Disa
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Pyddoke, Roger
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Optimal pricing of car use in a small city: a case study of Uppsala2019Report (Other academic)
    Abstract [en]

    Studies of cities which successfully have shifted mode choice from car to more sustainable modes, suggest that coordinated packages of mutually reinforcing policy instruments are needed. Congestion charges and parking fees can be important parts of such packages. This paper aims to examine the introduction of welfare optimal congestion charges and parking fees in a model calibrated to Uppsala, a small city in Sweden. The results suggest that welfare optimal congestion charges in Uppsala are as high as EUR 3.0 in the peak hours and EUR 1.5 in the off-peak. In a rough cost-benefit analysis it is shown that the introduction of congestion charges in Uppsala are welfare improving if operating costs of congestion charges are proportional to city population size (compared to Gothenburg). The model can be used to assess when it is worthwhile to introduce congestion pricing.

  • Johansen, Trond Cato
    et al.
    Ramboll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nordic certification of road marking materials in Iceland, Norway and Sweden 2017–20192019Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials, that applies to the countries of Denmark, Iceland, Norway and Sweden, was introduced in 2015. In these countries, a documented product approval is required in order to use a road marking material on roads managed by the national road authorities (Iceland from 2020). Product approval is based on monitored and documented performance measurements of material samples applied on test fields on public roads. The materials are approved (certified) in relation to the number of wheel passages they will stand, with preserved function.

    The certification system includes road marking materials for longitudinal and transverse road markings in categories with respect to colour (white, yellow), type (type I, type II, type II inlaid, antiskid, hand application, non-reflective with enhanced durability, and temporary) and thickness (0.4, 0.6, 1.5, 3 and 5 mm).

    The present report documents the follow-up performance measurements that were carried out at the Norwegian-Swedish test site in 2019, i.e. one-year follow-up measurements for materials applied in 2018 and two-years follow-up measurements for materials applied in 2017. The performance parameters include the coefficient of retroreflected luminance (RL) under dry and wet conditions, the luminance coefficient under diffuse illumination (Qd), the friction, the chromaticity in daylight, and the chromaticity of retroreflected light (yellow materials, only).

  • Johansen, Trond Cato
    et al.
    Ramboll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System. VTI.
    Nordic certification of road marking materials in Denmark 2017–20192019Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials, that applies to the countries of Denmark, Iceland, Norway and Sweden, was introduced in 2015. In these countries, a documented product approval is required in order to use a road marking material on roads managed by the national road authorities (Iceland from 2020). Product approval is based on monitored and documented performance measurements of material samples applied on test fields on public roads. The materials are approved (certified) in relation to the number of wheel passages they will stand, with preserved function.

    The certification system includes road marking materials for longitudinal and transverse road markings in categories with respect to colour (white, yellow), type (type I, type II, type II inlaid, antiskid, hand application, non-reflective with enhanced durability, and temporary) and thickness (0.4, 0.6, 1.5, 3 and 5 mm).

    The present report documents the follow-up performance measurements that were carried out at the Danish test site in 2019, i.e. one-year follow-up measurements for materials applied in 2018 and the two years follow-up measurements for materials applied in 2017. The performance parameters include the coefficient of retroreflected luminance (RL) under dry and wet conditions, the luminance coefficient under diffuse illumination (Qd), the friction, and the chromaticity in daylight.

  • Johnsson, Hans
    EQUA Simulation AB.
    Temperaturer i höghastighetsbanornas tunnlar: jämförelse mellan mätningar och beräkningar i befintliga tunnlar2019Other (Other academic)
    Abstract [sv]

    I denna rapport har förutsättningarna för att beräkningsmässigt hantera temperaturpåverkan i tunnlarna i de nya höghastighetsbanorna studerats genom jämförelser mellan mätningar och beräkningar för två befintliga tunnlar.

    Fältmätningar av bl.a. temperatur har under ett flertal år gjorts i Åsatunneln och Glödbergstunneln under ledning av Anna Andén, Trafikverket. Dessa mätningar har jämförts med beräkningsmodeller gjorda med programvaran IDA Tunnel som är en 1-D simuleringsmodell för analys av bl.a. luftrörelser och klimat i järnvägs- och biltunnlar. 

    Avsikten med jämförelserna är att validera IDA Tunnel som verktyg för att beräkna frysning m.m. för de nya tunnlarna som planeras för den nya höghastighetsbanan samt att identifiera områden där modellen behöver förbättras och utvidgas.

  • Göransson, Nils-Gunnar
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Polering av asfaltbeläggning: friktionsmätningar i Stockholmsregionen : 20092010Report (Other academic)
    Abstract [sv]

    För att studera trafikens poleringseffekt av vägytan, har under sommarhalvåret 2009 ett antal asfaltbeläggningar följts upp med avseende på friktion. Arbetet är en fortsättning på flera års mätningar av friktion på ytor som kan tänkas utsättas för polering. Det handlar om högtrafikerade vägar i Stockholmsområdet företrädesvis med slitlager av skelettasfalt (ABS16). Även några slitlager med inblandning av gummi respektive tunnskikt (TSK16) samt dränerande beläggning (ABD16) ingår i undersökningen. Ballasten består av porfyr eller kvartsit samt blandningar av porfyr och kvartsit eller porfyr och ortens material.

    Mätningarna följer Vägverkets metodbeskrivning för bestämning av friktion på belagd vägyta och avser våtfriktionen vid barmarksförhållanden. Vid mätningarna har VTIs friiktionsmätbil "SAAB Friction Tester" använts. Friktionen har mätts i högra hjulspåret.  

  • Cocron, Peter
    et al.
    Neumann, Isabel
    Kreußlein, Maria
    Pereira, Marta
    Wanner, Daniel
    Drugge, Lars
    Bierbach, Maxim
    Augusto, Bruno
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Driver and vehicle behaviour to power train failures in electric vehicles: experimental results of field and simulator studies2014Report (Other academic)
    Abstract [en]

    New electric power trains can be subject to different failures when compared to those arising in conventional vehicles. The objectives for active safety investigations within the EVERSAFE project (work package 2) were to address vehicle stability under these failure conditions and the driver response to relevant types of failures. Failure conditions that affect the vehicle stability are believed to be significantly different from today’s conventional internal combustion engine cars, and may potentially be a substantial safety problem if not treated in a correct manner. To study these effects, two examples of system failures and their consequences on the driver response and vehicle stability were investigated with the help of three studies.

    The first two studies investigated a failure of wheel hub motors (WHMs), an emerging technology among the future generation of electric vehicles (EV). The main benefits of a WHM are its controllability, high efficiency, high power density and low weight. However, the direct connection to the wheel comes along with the potential disadvantage in case a failure occurs in the system. Therefore, those WHM failures are to be analysed in this study. A possible failure with severe consequences to the driving task could be a constant brake torque applied to one of the wheels, which leads to a sudden yaw torque and subsequently to a deviation from the desired path of driving. As a consequence, a compensatory control action by the driver is necessary. The impact of this failure of WHMs on the drivers was assessed twofold in the EVERSAFE project. On the one hand a driving simulator study investigated the impact of WHM failures under high speed conditions (110 km/h). On the other hand these failures were investigated in a test track study at lower speeds (30 km/h). Both studies examined the following three manoeuvres: a failure while straight line driving as well as two failures while driving in a curve, i.e. on the inner and the outer rear wheel respectively. Drivers were asked to evaluate the failure situation regarding perceived stress, risk, lack of control, workload and disturbance. Furthermore, objective data collected via the data logger (steering wheel angle, accelerator pedal travel, brake pressure, speed, yaw rate, longitudinal and lateral acceleration) contributed to shed light on the driver response and vehicle stability. The results of the subjective ratings of both studies revealed a low to medium level of perceived failure severity for all tested failures. It can be concluded from the outcomes of the simulator study, that WHM failures at speeds of 110km/h are rated more stressful, risky, disturbing and demanding than driving without an occurring failure. With regard to the test track study these differences occurred only for the straight inward failure. Comparing the subjective evaluations in the simulator and the field study, it can be assumed that failures are perceived as more severe at higher than at lower speeds. The simulator study showed steering as the main reaction to all failures. Regarding the test track study a steering reaction was only detected for the curve inward failure. Consequently, the outcomes of the subjective evaluations of the simulator study and driving data of both studies lead to the assumption that the curve inward failure is the most severe amongst the failures tested here. As participants in both studies used the accelerator pedal during failure activation, regardless of failure type, it could be concluded that drivers try to overrule the deceleration triggered by the failure at low as well as at high speeds. Whether this was an effect of the instruction to maintain a steady speed should be clarified by further research. Generally speaking, results of both studies showed that humans can compensate WHM failures well, at least for the specific settings of the studies. However, further research is needed to investigate if and how these conclusions are applicable, for instance, in case of a higher workload of the driver (e.g., in more complex driving situations).

    The third study conducted within the active safety focus of the EVERSAFE project examined a failure of the regenerative braking (RB) system. The latter is a system designed to convert kinetic energy to chemical energy stored in the energy storage system (i.e. battery) while the vehicle decelerates. In the tested configuration this energy recapture is triggered via the accelerator pedal and therefore decelerates the car whenever the driver releases that actuator. In case the RB system fails to operate properly, hazardous situations might occur because the driver expects a deceleration of the car which is inexistent due to the failure. In order to study the effects of a RB failure on driver behaviour and perception as well as on vehicle stability, a test track study was conducted. Similar to the WHM failure testing, the failure situation was evaluated with the help of subjective ratings (stress, risk, lack of control, disturbance, workload) and data logger records (steering wheel angle, accelerator pedal travel, brake pedal pressure, speed, yaw rate, longitudinal and lateral acceleration). The RB failure was implemented during a deceleration manoeuvre when entering a curve at a speed of about 50 km/h. Whereas half of the participants were informed that a RB failure might occur, the other half was not informed. Results revealed that only about 50% of the subjects noticed the RB failure, but compensation efforts were manageable. Although the situation was rated more risky than solely driving on a road, the RB failure did not induce more stress or workload. Informing people about an upcoming failure yielded a higher frequency of mild braking manoeuvres. It is important to note that failure of RB system will incur in higher vehicle speeds than the ones originally expected by the driver under normal circumstances. Depending on the road conditions (e.g., wet/icy surface) or even the road geometry (e.g., curve driving) the unexpected high velocity might even lead to vehicle instability thus compromising the safety of the occupants as well as the general traffic flow. These aspects should be considered in future research.

  • Thomson, Robert
    Swedish National Road and Transport Research Institute.
    Recommendations for New Safety Requirements and Research2014Report (Other academic)
    Abstract [en]

    The main objective of EVERSAFE is to facilitate integration of electrical vehicles (EVs) into European vehicle traffic. The performance and control characteristics of electric machines also offer more opportunities for vehicle designs and systems that benefit segments of the population, an example being semi-automated vehicles that provide mobility to an aging population. There are many opportunities for a strong market value of European vehicle manufacturers that can be exported worldwide.

    Customer acceptance increases when EV safety is guaranteed for normal operation or an accident. The consequences of a negative image for EVs are considerable and will limit the development and penetration of a new vehicle type that can have financial, environmental, and social benefits for Europe. The EVERSAFE project had three main areas of research to ensure a robust market for EVs:

    1. The perceptions of electric vehicles from a user point of view
    2. Investigations of vehicle safety encompassing both active and passive vehicle safety implications that are part of the vehicle’s design
    3. Developing guidelines and recommendations for post-crash handling of electric vehicles that are not addressed in the practice for conventional (internal combustion) drivelines

    The research plan was developed to identify the most high risk scenarios, investigate their potential consequences, and identify any corrective actions in terms of further research, industry standards, or government regulations.

    The project used focus groups of consumers to identify perceived issues as well as expert judgement to identify specific research cases. Building on accident analysis, critical load cases for investigation for both active and passive safety were identified. Lateral and longitudinal load conditions for the vehicle were identified. For active safety the longitudinal case of interest was regenerative braking and yaw stability due to wheel hub motor failure on one wheel was the lateral case. Passive safety research was focused on pole side impacts for the lateral load case and rear end crashes for the longitudinal case. Post-crash handling of vehicles with electric drive trains was also identified as an area for investigation.

    The main findings of the active safety investigations suggested that the potential failures for regenerative braking and wheel hub motors could be compensated by the drivers. Volunteer drivers participated in controlled studies in a driving simulator and a modified vehicle. For the investigated controlled cases there were no major safety issues identified, however the cases were not in real traffic and did not present complex traffic threats.

    Passive safety investigations used component tests of battery cells, full scale crash tests, and numerical simulations to study the risks during a crash. The tested cells and vehicle crash tests demonstrated good safety levels. The simulations and component tests were useful to identify that the main risk for vehicles is crushing the battery pack and battery modules.

    The safe handling of electric vehicles after a crash requires updates to the conventional rescue operations. The main issue is to identify when an electric vehicle is involved in a crash and to ensure the high voltage system is disconnected and preferably neutralized.

    The results of the EVERSAFE project indicate that the general level of EV safety is quite high and that no critical safety issues have been identified. There are areas where the industry should develop universal standards to improve the driver interaction with the new EV systems and minimise the risk of crashes due to inappropriate driver expectations. When a crash with an EV occurs there appears to be little chance for fire or the emission of toxic substances, but there needs to be more work to assist the firefighters in identifying EVs, disconnecting electrical systems, and possibly neutralizing batteries after a crash.

    Improving safety for the road user is an ongoing process and EVERSAFE has recommendations to further improve the good level of safety of the existing vehicle fleet. The results of EVERSAFE indicate that current and potential owners of vehicles with electric drivetrains should not consider these vehicles as less safe than vehicles with conventional (internal combustion) drivetrains.

  • Häring, Ivo
    et al.
    FHG.
    Kanat, Bülent
    EMI.
    Risk management approach2013Report (Other academic)
    Abstract [en]

    The EVERSAFE project has the challenge to identify potential safety issues for vehicles which have had limited commercial sales, and thereby, limited field data to document safety and reliability issues in terms of event details and frequency. ISO 26262 is a new branch specific standard for functional safety of automotive electrical/ electronic/ programmable electronic (E/E/PE) systems carrying out a safety function. The standard aims to identify the potential hazards caused by malfunctions of E/E/PE systems, to assess their risks and to reduce the risks demonstrably to an acceptable level by taking the appropriate countermeasures. As safety investigations are part of EVERSAFE project, ISO 26262 is a relevant approach for this project. In addition, the determination of risks that must be further reduced is covered by the safety life cycle of ISO 26262, independent of their reduction by E/E/PE safety functions or not.

    The EVERSAFE project is planning a workshop to identify the main safety risks that should be addressed in the project. The main goal of this report is to review the ISO 26262 and to identify the safety life cycle phases that are covered by project activities for active safety investigation of EVERSAFE. This framework will be a basis for the workshop. Of particular relevance is the Automotive Safety Integrity Level (ASIL) system that provides a system for identifying the hazards, their exposure (expected frequency) to the vehicle occupants, controllability by the driver, and the resulting severity. For this purpose, the scope, structure and content of ISO 26262 are described in detail. In particular, safety life cycle phases, their requirements and analysis methods to fulfil them are presented.

  • Wisch, Marcus
    et al.
    BASt.
    Ott, Julian
    BASt.
    Thomson, Robert
    Swedish National Road and Transport Research Institute.
    Léost, Yann
    EMI.
    Abert, Michael
    ICT.
    Yao, Jianfeng
    VCC.
    Recommendations and Guidelines for Battery Crash Safety and Post-Crash Safe Handling2014Report (Other academic)
    Abstract [en]

    Electric vehicles (EV) present a research challenge for safety engineers. These vehicles are designed using conventional vehicle design strategies but do not contain conventional materials or structures. Accident analyses cannot be conducted until sufficient EVs are involved in a crash and are reported in crash databases. Until such data exists, researchers must use other research methods to understand and predict potential problems.

    The passive safety activities in the EVERSAFE project used conventional accident analysis, computer simulation, physical testing, and literature reviews to get a better understanding of the issues for EV and their battery systems. Based on current practice, Lithium-ion (Li-ion) batteries are the main chemistry that should be explored and pouch type cells are the most vulnerable for damage.

    Conventional vehicles were used in EVERSAFE as a surrogate for EVs to identify expected deformation and acceleration loads from real crashes. Based on available information and previous compatibility research, the main issue that arose was that for small vehicles. These vehicles experience the highest accelerations in car-car crashes and even some fixed barrier crashes. Except for a handful of cases, there was not enough data to confirm that EVs have a higher injury or fire risk than similar conventional vehicles.

    Chemical analyses of the battery components identified the potential processes that can lead to emissions of flammable or toxic gases. These chemicals develop when the battery temperatures are too high and can develop if mechanical loading causes an internal short circuit or an external heat source affects the battery. There are several harmful chemicals contained in battery electrolytes and hydrofluoric acid (HF) appears to be the most relevant gas to monitor.

    Simulation activities in EVERSAFE have developed new battery models and an effective methodology to assess worst case loading in a battery was also developed. The models were used to explore both local cell-level deformations as well as whole vehicle crash performance. The simulations confirmed the ability of ductile structures to protect the battery and at the same time identify the risks created when the battery pack structures start to deform and result in crushing of the cell structures.

    Component tests of the battery cells demonstrated that the pouch cell can be quite resilient to shear and penetration loads. They are more sensitivity to crushing loads and the ductile plastic structures in the battery can be a useful safety element. This information underlines the need to maintain the battery in an undeformed part of the vehicle.

    Full scale crash tests demonstrated safe battery performance even for more severe tests than those the vehicle are required to meet. Both a side impact and a rear/front multiple impact could not provoke thermal activity or hazardous emissions from the battery in a Mitsubishi iMiEV or a BMW i3. These results can be used to promote consumer trust in the technologies.

    A complementary part of the study was to determine what procedures and equipment are needed for rescue services if they attend a crash with an EV. There appears to be no fundamental changes in the rescue approach at a crash scene. There is a need for better support for rescue services to identify the type of energy source (internal combustion, electric, or both) of a given vehicle. There are some actions needed for an EV that must be considered when attending a crash and these can only be done when the vehicle is known to be an EV. eCall is one tool that can facilitate the identification of EVs as well as update the status of the battery to the rescue services. Rescue sheets are being developed in ISO committees and these need to be made available in standard and secure locations in a vehicle. There is the potential for fire and toxic gas and a firefighter must be able to identify the appropriate type of safety equipment to wear. Knowledge of the chemical processes that

    can occur in a battery is important. It is more important that firefighters have access to methods that

    identify risk of fire or chemical hazards. Thermal imaging cameras and portable gas detectors,

    already available on rescue vehicles, may be sufficient for monitoring EVs at a crash site.

  • Arvidsson, Håkan
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Jämförande provning – grovsiktning: ballast 20182019Report (Other academic)
    Abstract [en]

    This report shows results, some statistical analysis and precision data for interlaboratory comparison (round robin) in Sweden performed on a proportioned base layer material of crushed rock for grain size distribution according to TDOK 2014:0145 (coarse material sieving) and EN 933-1:2012 (sieving on 0/16 mm).

    There were 48 laboratories participating.

    In the sieving on coarse material, ≥ 16 mm, the deviations are small (standard deviations approx. 0,7%) and the difference between maximum and minimum value for each sieve is only 3–4%.

    The results for material finer than 16 mm (relatively to whole of the sample) are deviations wider. Especially for sieves 1/11,2 mm with difference between maximum and minimum values are up to 7% and the standard deviation for those sieves are around 1,4%. For sieves finer than 1 mm (0,5 mm and less) the differences are less than 3% and the standard deviation is less than 0,8%.

    The spreading’s for the fine material sieving is wider than for the coarse sieving part. It could depend on less accurate gradings on the fractions finer than 16 mm that were used in the proportioning. For the coarse sieving the whole sample (18 kg) were the test portion, for the fine sieving the material 0/16 mm had to be divided to get the test portion (approx. 2,6 kg). The dividing can also be one of the reasons to less accurate results for the 0/16 mm-part.

  • Odolinski, Kristofer
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Pyddoke, Roger
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Price elasticities of demand for (garage) parking in Stockholm2019Report (Other academic)
    Abstract [en]

    There is scope for generating welfare effects by changing parking fees, where knowledge on price elasticities are central elements in the implementation of an efficient parking policy. In this paper, we estimate price elasticities of demand for five parking garages in the central business district of Stockholm, using transaction data and a price increase implemented in January 2017. The econometric results for the purchased parking hours show an average elasticity estimate at -0.60, while the effect on the decision to park is -0.45. These elasticities vary for the different parking garages, showing that there is a considerable heterogeneity between garages, even within the central business district, which needs to be considered for an efficient parking policy. Based on our estimated elasticity for garage parking (-0.60) and a willingness to pay a premium for curbside parking in previous research, we calculate a proxy for the elasticity of curbside parking in Stockholm, which is found to be -0.39.