Several different heavy vehicle combinations are allowed on the Swedish road network. A commonly seen combination is the tractor and semi-trailer combination with a maximum total length of 16.5 meters. The legal limitation on the total length of the combination has led to the use of a short tractor to make space for more goods on the trailer. There is a concern that the shortness of the tractors will have a negative consequence on traffic safety and the ability to negotiate uphills. The short wheelbase of the tractor and the weight imbalance between the tractor and the semitrailer could be an issue when braking and negotiating turns. 

This study was ordered by the Swedish Transport Agency to investigate the traffic safety aspects and hill-climbing problems of certain heavy vehicle combinations. The concerns raised should be investigated from a vehicle dynamical point of view for the vehicle combinations in question and compare them with other common vehicle combinations through a simulation study. 

A set of tractor and semitrailer combinations have been simulated in severe conditions and maneuvers to investigate the vehicle response and its dependencies with respect to the wheelbase of the tractor, coupling length, fifth wheel lubrication, and road surface conditions. Whenever meaningful, a comparison was made with a Nordic combination (truck and full trailer) as well as a B-double combination (tractor, link trailer, and trailer). 

The overall result of the simulation study is that the tractor and semitrailer combination is a stable combination, which outperforms the longer and heavier Nordic and B-double combinations in all the measured situations and maneuvers where comparison is meaningful. Furthermore, the wheelbase of the tractor seems to have a very minor effect on the performance of the vehicle combinations.

Flera olika typer av tunga fordonskombinationer är tillåtna på det svenska vägnätet. En vanlig kombination är dragbil och påhängsvagn med en total längd på 16,5 meter. Den lagliga begränsningen av kombinationens totala längd har lett till att en kort dragbil används för att ge plats för mer gods på släpvagnen. Det finns en oro för att dragbilens korthet kan få en negativ konsekvens för trafiksäkerheten och förmågan att klara backar. Dragbilens korta hjulbas och obalansen i vikt mellan dragbilen och påhängsvagnen skulle kunna utgöra ett problem när du bromsar och svänger. 

Denna studie är beställd av Transportstyrelsen för att undersöka trafiksäkerhetsaspekterna och problem med backstigning för vissa tunga fordonskombinationer. Den oro som beskrivs undersöks ur ett fordonsdynamiskt perspektiv för de aktuella fordonskombinationerna och jämförs med andra vanliga fordonskombinationer genom en simuleringsstudie. 

En uppsättning kombinationer av dragbilar och påhängsvagnar har simulerats under extrema förhållanden och manövrar för att undersöka fordonets svar och dess beroenden på dragbilens axelavstånd, kopplingslängd, femte hjulsmörjning och vägytans förhållanden. Där det är meningsfullt gjordes en jämförelse med en nordisk kombination (lastbil och full släpvagn) samt med en B-dubbelkombination (dragbil, länkvagn och påhängsvagn). 

Det samlade resultatet av simuleringsstudien är att kombinationen av dragbil och påhängsvagn är en stabil kombination, som överträffar de längre och tyngre kombinationer av nordiska och B-dubblar i alla uppmätta situationer och manövrar där jämförelsen är meningsfull. Dragbilens hjulbas och kopplingsavstånd verkar dessutom ha en mycket liten effekt på fordonskombinationernas prestanda.

A commonly seen vehicle combination on the European road network is the tractor-semitrailer with a maximum legal length of 16.5 m. In Nordic countries longer tractor-semitrailers are allowed, which makes tractors with larger wheelbase an appealing option. Concerns have been raised that shorter tractors have poorer performance and are involved in more accidents than the Nordic equivalents, especially in winter conditions. To answer the raised questions and concerns, this paper investigates the effects of a tractor wheelbase length on performance of a vehicle combination, as well as other influencing factors such as lubrication of the fifth when, loading condition and road friction level. Six tractor-semitrailer combinations with different wheelbases and axle configurations are modeled and compared. Nordic (truck-dolly-semitrailer) and B-double (tractor-link trailer-semitrailer) combinations, which are common in Nordic countries, are also used as reference vehicles in the comparison. Three maneuvers are simulated to provoke dangerous situations, namely braking with all wheels in a curve, engine braking in a curve and a fast single lane change. The results show that wheelbase alone does not have a major role in the outcome of the simulations, but a combined influence of axle configuration, wheelbase, fifth wheel position and axle loads determines the vehicle performance. Factors such as existence of a working anti-lock braking system or lubrication of the fifth wheel have a large effect on the vehicle performance, under the tested conditions.

In-vehicle technologies are essential for vehicle safety. This project, Quantitative Driver Behavior Modeling for Active Safety Assessment Expansion (QUADRAE), addresses two crucial components of the technology development process: driver models and simulation methodology. Together, they have provided the industrial partners with state-of-the-art tools for system development and testing, facilitating the development of innovative technologies to improve traffic safety. The main objectives of the project were to:

• develop and validate models of driver behavior needed in current and future simulation tools for virtual testing of active safety and automation
• carry out prioritized virtual tests to estimate the safety benefit of a system, tune system parameters, and explore potential outcomes in scenarios when the system is active
• learn more about the best methods for performing virtual testing using driver models

As a result of the project, the partners now have an established virtual simulation framework using Predictive Processing (PP) as a general paradigm for modeling driver behavior. The modeling, based on the latest knowledge and ideas about human behavior in driving, draws on extensive research using volunteer drivers as study participants. Data from both controlled experiments and naturalistic driving were used to develop and validate the models. These models are already being used by the industry partners as part of their virtual safety assessment toolchain, to develop advanced driver support systems. The data will continue to be used by the project partners in industry and academia to develop future driver models (which will, in turn, foster improved driver support systems).

The forces in the couplings of articulated vehicle combinations, propel and fully determine the path of any towed unit thus playing a significant role in the vehicle behavior. A failure in the coupling could potentially have a devastating effect if it occurs while driving in traffic. To prevent this from happening, states and road authorities impose requirements in terms of tolerated forces on any coupling selection. The current legal requirement framework is based on an ISO standard, that stipulates minimum force levels that the couplings should stand. These forces have been derived under semi-empirical assumptions for a set of five vehicle combinations. The present report aims to extend the coupling requirements to two vehicle combinations that are candidates to become legal on the public road network. Due to the semi-empirical nature of the ISO standard, validation needed to be performed. The here presented requirements for the two new combinations were validated against simulation models and checked for reasonable requirements for some example weights of the combinations. The proposed requirements are aligned with the existing requirements derived from the ISO standard. This implies that they could be used to form the legal requirements on these vehicle combinations. However, further investigations on well-grounded deduced requirements should be performed to secure safety margins.

Kopplingskrafterna hos fordonskombinationer är de krafter som helt styr vart efterföljande fordon tar vägen. Ett brott på en sådan koppling kan därför få förödande konsekvenser om det inträffar i trafik. För att minska risken för sådana händelser, ställer myndigheter krav på bärighet hos dessa kopplingar. Det nuvarande rättsliga kravet är baserat på en ISO-standard som anger de minsta kraftnivåer som kopplingarna ska tåla. Dessa krafter har härletts utifrån semi-empiriska antaganden och explicita uttryck finns angivna för fem olika fordonskombinationer. Denna rapport syftar till att utöka kravet på kopplingskrafterna för två nya fordonskombinationer som i en framtid kan bli lagliga på det allmänna vägnätet. På grund av uttrycken i ISO-standardens semiempiriska natur, måste validering utföras. En jämförande simulering av kopplingskrafterna för de två nya samt de i ISO standarden existerande utgör en del i valideringen. En rimlighetskontroll av resultatet av uttrycken med existerande kopplingar på marknaden utgör den andra delen av valideringen. Valideringen visar att uttrycken ger rimliga krav som är i linje med vad ISO-standarden ger för existerande fordonskombinationer. Detta innebär att de kan användas som grund för framtida lagkrav för dessa fordonskombinationer. Ytterligare undersökningar av välgrundade, deducerade krav bör dock utföras för att säkerställa säkerhetsmarginaler och reducera empirin.

This article investigates the potential of a motion-based driving simulator in the field of vehicle dynamics testing, specifically for heavy vehicles. For this purpose, a case study was prepared embodying the nature of a truck dynamics test setup. The goal was to investigate if the drivers in the simulator could identify the handling differences owed to changes in vehicle parameters, while driving the simulated trucks. Results show that the drivers could clearly identify the differences in vehicle behaviour for most of the performed tests, which motivates further investigative work in this area and exposes the feasibility of heavy vehicle dynamics testing in simulators.

This article investigates the potential of a motion based driving simulator in assessing and comparing dynamic performance of different heavy vehicles. A driving simulator study with 55 professional truck drivers is performed and the achieved results show a strong correlation between the objective and subjective measures of the different vehicles performance. The motion based driving simulator is used to compare the performance and controllability of high capacity transport vehicles with conventional heavy vehicles.

The process of developing new automotive systems includes various testing cycles to assure a save operation in traffic. Physical system testing on test tracks is very important for this purpose, but rather expensive and might only become possible in later stages of the development process. Using a virtual simulation environment offers a safe possibility of testing new systems in early stages of development. Aditionally, driver-in-the-loop tests at test track and in a virtual simulator make it possible to evaluate driver reaction and potential acceptance by the future users of those systems. Within PROSPECT the new functions are investigated under various aspects in several simulator studies and test track studies.

This deliverable D7.3 gives detailed information of conduction and results of the each study. Three studies focus exclusively on the for Vulnerable Road Users (VRUs) specifically dangerous urban intersection scenarios. The first of those studies examines the driver behaviour in a turning situation when a byciclist might be crossing. The second study, which provides an initial step in this line of research, analyzed the acceptance of issued forward collision warning times. In the third study acceptance of an intersection assist autonomous emergency braking systems was tested regarding the acceptance of potential buyers.

Two studies focused on longitudinal scenarios. Both studies followed the same design, but one was conducted on a test track and the other one in a simulator. The main objective was to investigate drivers reactions to FCW warnings and Active Steering interventions in critical VRU scenarios in case of a distraction of the driver.

VDTestS set out to probe the potential of a driving simulator in the field of vehicle dynamics testing. For this purpose, a simulator test case was prepared embodying the nature of a vehicle dynamics test set-up. The goal was to figure out if the drivers in the simulator could identify the handling differences owed to changes in vehicle settings, while driving simulated trucks.

A truck model was validated against the performance of a real vehicle under a predefined set of manoeuvres. This was coupled with the tuning of the simulator motion to improve the perception of the vehicle dynamics. These efforts were followed by definition of a group of four test cases, each corresponding to a set of alternate vehicle properties. These sets were selected based on their potential impact on the vehicle handling and correlation with changes that could occur in a real vehicle. Finally, experiments were conducted in VTI’s motion-based driving simulator, Sim IV in Gothenburg, with participation of ten engineers and mechanics from VGTT product development well familiar with truck mechanics and truck driving. The set-up made it possible to gather feedback, about the suitability of the driving simulator in these testing conditions, from professionals in the field. Data was collected subjectively via interviews and questionnaires as well as objectively from the logs comprising of driver inputs and vehicle motions generated during the simulator drives.

Single vehicle accidents are commonly caused by fatigue and distraction and resulting in severe casualties and high economic costs. In order to evaluate driver recovery from run-off-road accidents, comprising of 80% of fatal crashes on rural roads, a simulator study in an advanced full-motion driving simulator was carried out. Drivers were given a secondary task to perform at six positions down the road (to simulate distraction), and an artificial yaw deviation was added to the vehicle to induce a run-off-road accident whilst the driver was distracted. The results show that the severity of the recovery manoeuvre was larger than similar events caused by the failure of automated lane keeping systems, leading to lane departures. Furthermore, significant learning effects was found, providing recommendations for further studies into run-off-road experiments.

The aim of this project was to develop a lane-change scenario for driving simulators to analyse the characteristics of lane-change manoeuvres performed with heavy vehicles.

The definition of the lane-change scenario was based on a literature review, and an investigation of lane-change accidents in Sweden.

A lane-change manoeuvre is in the literature typically described by accepted gap at the initiation of the manoeuvre as well as duration of the manoeuvre and speed during the manoeuvre. The literature review showed that there is a lack of real-world data regarding lane-change manoeuvres with heavy vehicles. The data that exist are collected mainly in the US and for discretionary lane changes, and a distinction between sizes of heavy vehicles is rarely made. Regarding accidents involving heavy vehicles on European level, there is a general lack of useful and reliable accident data. The most comprehensive data are available from the US and show that lane-change accidents account for a large share of accidents involving heavy vehicles.

The investigation of lane-change accidents was made in the Swedish Traffic Accident Data Acquisition (STRADA), on 10 500 police-reported accidents with heavy vehicles involved during the years 2003 to 2013. In STRADA, lane-change accidents are categorized together with overtaking accidents. Therefore, it is not possible to identify lane-change accidents and their share of heavyvehicle accidents directly from STRADA. Instead, lane-change accidents were identified by reading the accident narratives for overtaking accident and rear-end accidents (in total 5 612 accidents). Rearend accidents were included because the manner of collision may resemble lane-change collisions.