Search

The gradual deployment of automated vehicles on the existing road network will lead to a long transition period in which vehicles at different driving automation levels and capabilities will share the road with human driven vehicles, resulting into what is known as mixed traffic. Whether our road infrastructure is ready to safely and efficiently accommodate this mixed traffic remains a knowledge gap. Microscopic traffic simulation provides a proactive approach for assessing these implications. However, differences in assumptions regarding modeling automated driving in current simulation studies, and the use of different terminology make it difficult to compare the results of these studies. Therefore, the aim of this study is to specify the aspects to consider for modeling automated driving in microscopic traffic simulations using harmonized concepts, to investigate how both empirical studies and microscopic traffic simulation studies on automated driving have considered the proposed aspects, and to identify the state of the practice and the research needs to further improve the modeling of automated driving. Six important aspects were identified: the role of authorities, the role of users, the vehicle system, the perception of surroundings based on the vehicle’s sensors, the vehicle connectivity features, and the role of the infrastructure both physical and digital. The research gaps and research directions in relation to these aspects are identified and proposed, these might bring great benefits for the development of more accurate and realistic modeling of automated driving in microscopic traffic simulations., Funding agencies: Applied and Technical Sciences (TTW), a subdomain of the Dutch Institute for Scientific Research (NWO) through the Project Safe and Efficient Operation of Automated and Human-Driven Vehicles in Mixed Traffic (SAMEN) (Grant Number: 17187)Swedish Transport Administration (Trafikverket) through the Project Simulation and Modeling of Automated Road Transport (SMART) (Grant Number: TRV 2019/27044)

Traffic breakdowns are frequently observed phenomena on roads in larger cities, especially during peak hours. Locations along a road stretch with frequently observed breakdowns are known as recurrent bottlenecks. Knowledge about bottleneck locations are important for improvement of traffic conditions at these locations. Bottleneck locations can be identified through manual inspection of data. However, due to the comprehensive amount of data that are available today, it becomes impractical to manually identify breakdowns and instead, an automated process can be used. We propose such an automated method. The proposed method is applied to a use case south of Stockholm in Sweden. One month of data collected at densely spaced detectors is used to investigate the sensitivity of the parameter settings. After calibration of the threshold values, 100% of the larger breakdowns and 40% of the medium size breakdowns are identified. Smaller breakdowns, not giving significant impact on the traffic conditions, are only detected in 10%-20% of the cases. Thereafter, the method is applied to 1 year of data to illustrate the applicability of the method on a larger data set. The results show that the method is promising to use for identification of recurrent bottleneck locations., Funding Agencies|Swedish Transport Administration (Trafikverket) through the Centre for Traffic Research (CTR); [TRV 2017/68538]

To simulate bicycle traffic accurately, it is essential to capture how bicyclists react to features of the infrastructure such as the longitudinal gradient of a bicycle path. Bicycling requires human-powered motion, and the power output provided by bicyclists differ significantly among bicyclists due to physical capabilities and preferences. Therefore, the objective of this paper is to investigate the connection between power output and gradient in bicycle traffic, with the purpose of developing a power-based model that predicts accurately the speed of bicyclists. Based on trajectory data of free-riding bicyclists travelling on a non-flat bicycle path segment, we estimate changes in power output as a function of gradient considering the physical forces acting on a bicycle. The results suggest a linear correlation between power output and gradient; while bicyclists increase their power output on the uphill as gradient increases, they decrease their power output on the downhill as gradient increases. By implementing this correlation into a traffic simulation algorithm, we show that the simulation captures well the impact of gradients in a population of bicyclists as it reproduces similar speed profiles. We conclude that bicyclists adapt their power output to compensate for the gradient and its associated change in speed, and that the impact of gradient varies greatly among bicyclists. Furthermore, we conclude that power-based modelling of free-riding bicyclists is an attractive alternative to investigate further.

The gradual deployment of Connected and Automated Vehicles (CAV) in traffic will result in a transition period in which vehicles with various levels of automation and connectivity will have to co-exist with non-connected and non-automated road users for quite some time. Consequently, new types of interactions will emerge (and old types of interactions are likely to become more complicated) between vehicles at different levels of automation and other road users which could have significant implications on traffic safety and efficiency. Understanding the nature of these interactions, how humans might adapt their behavior, how connectivity can be utilized to proactively enhance drivers char63 driving performance, and how automated vehicles can be programmed to behave in different driving situations to guarantee safety and efficiency remain among the key knowledge gaps that require scientific research. This knowledge is crucial for the development of adequate integration policies of connected and automated vehicles in mixed traffic environment, for updating and improving automated vehicles char63 algorithms and software, for designing the physical and digital road infrastructure, and for operating and managing traffic on the road network., Funding Agencies|Applied and Technical Sciences (TTW), a subdomain of the Dutch Institute for Scientific Research (NWO), through the project "Safe and Efficient Operation of Automated and Human-Driven Vehicles in Mixed Traffic (SAMEN)" [17187]; Australian Research Council [DP210102970]

Mixed traffic with automated and human-driven vehicles interacting with one another will soon become a common reality. Microscopic traffic simulation can preemptively help assess the impact on the traffic flow dynamics as long as the tools adequately capture the differences on how automated driving systems (ADSs) drive compared to humans. In this work a modeling approach that captures differences in perception performance is proposed. While human drivers perceive through their senses and cognitive processes, ADS perceive the driving context through on-board sensors, connectivity features and software. The perception performance is described in terms of accuracy, precision, detection range, and detection delay. The model for perception is implemented in SUMO and a simulation test in a platoon shows the acceleration response affected by up to 35% for perception errors of approximate to 10% which by extension will affect the traffic flow dynamics. The proposed modeling approach for perception contributes to the robustness of microscopic traffic simulation and the modeling of heterogeneous mixed traffic., Funding Agencies|Swedish Transport Administration via the Centre for Traffic Research (Trafikverket) [TRV 2022/8287]

Microscopic emission models estimate second-by-second emissions and fuel consumption for individual vehicles based on vehicle trajectories. A vehicle trajectory describes how the position, speed and acceleration of a vehicle evolves over time. In practice, collecting a complete trajectory data set on a road stretch is not always feasible due to economic and privacy constraints. Therefore, several researchers suggest approaches for generating Virtual Vehicle Trajectories (VVT) given some partially observed traffic data. However, the traditional VVT generation approaches, being originally developed for travel time estimations, usually consider a simplified description of vehicle kinematics, hindering their applicability in emission modelling. In this paper, we suggest a novel approach for generating VVT, which facilitates their use in emission modelling. We empirically evaluate our method by comparing it to the traditional approaches. The results are promising, showing that, under certain experimental settings, our method can enhance the accuracy of emission estimations., Funding Agencies|Swedish Transport Administration [2018/134733]; Swedish Energy AgencySwedish Energy AgencyMaterials & Energy Research Center (MERC) [43258-1]

The gradual deployment of automated vehicles on the existing road network will lead to a long transition period in which vehicles at different driving automation levels and capabilities will share the road with human driven vehicles, resulting into what is known as mixed traffic. Whether our road infrastructure is ready to safely and efficiently accommodate this mixed traffic remains a knowledge gap. Microscopic traffic simulation provides a proactive approach for assessing these implications. However, differences in assumptions regarding modeling automated driving in current simulation studies, and the use of different terminology make it difficult to compare the results of these studies. Therefore, the aim of this study is to specify the aspects to consider for modeling automated driving in microscopic traffic simulations using harmonized concepts, to investigate how both empirical studies and microscopic traffic simulation studies on automated driving have considered the proposed aspects, and to identify the state of the practice and the research needs to further improve the modeling of automated driving. Six important aspects were identified: the role of authorities, the role of users, the vehicle system, the perception of surroundings based on the vehicle’s sensors, the vehicle connectivity features, and the role of the infrastructure both physical and digital. The research gaps and research directions in relation to these aspects are identified and proposed, these might bring great benefits for the development of more accurate and realistic modeling of automated driving in microscopic traffic simulations., Funding agencies: Applied and Technical Sciences (TTW), a subdomain of the Dutch Institute for Scientific Research (NWO) through the Project Safe and Efficient Operation of Automated and Human-Driven Vehicles in Mixed Traffic (SAMEN) (Grant Number: 17187)Swedish Transport Administration (Trafikverket) through the Project Simulation and Modeling of Automated Road Transport (SMART) (Grant Number: TRV 2019/27044)

Microscopic traffic simulation is a useful tool for the planning of motorized traffic, yet bicycle traffic still lacks this type of modeling support. Nonetheless, certain microscopic traffic simulators, such as Vissim, model bicycle traffic by applying models originally designed for car traffic. The gradient of a bicycle path has a significant impact on the speed of cyclists; therefore, this impact should be captured in microscopic traffic simulation. We investigate two calibration approaches to reproduce the effect of gradient on the speed of cyclists using the default driver behavioral model in Vissim. The first approach is to modify the simulated gradient to represent different values of the gradient-acceleration parameter: a fixed value that represents a decrease in the maximum acceleration that cyclists can apply on an uphill. The second approach is to adjust the maximum-acceleration function. We evaluate both approaches by applying a Vissim model of a bidirectional bicycle path with a 3% gradient in Stockholm. The results show that the current default implementation in the Vissim model underestimates the effect of gradient on speed. Moreover, the gradient-acceleration parameter does not directly reduce the maximum acceleration of all cyclists, but only of those cyclists riding above a certain speed. We conclude that by using a higher gradient-acceleration value than the default, we accurately estimate the observed mean speed on the uphill. However, neither of the investigated calibration approaches provides accurate estimates of the speed distributions. We emphasize the need for developing more accurate behavioral models designed for cyclists., Funding Agencies|Swedish Transport Administration (Trafikverket) via Centre for Traffic Research (CTR) [TRV 2019/84465]

Dynamic Network Loading (DNL) models are typically formulated as a system of differential equations where travel times, densities or any other variable that indicates congestion is endogenous. However, such endogeneities increase the complexity of the Dynamic Traffic Assignment (DTA) problem due to the interdependence of DNL, route choice and demand. In this paper, attempting to exploit the growing accessibility of traffic-related data, we suggest that congestion can be instead captured by exogenous variables, such as travel time observations. We propagate the traffic flow based on an exogenous travel time function, which has a piece-wise linear form. Given piece-wise stationary route flows, the piece-wise linear form of the travel time function allows us to use an efficient event-based modelling structure. Our Data-Driven Network Loading (DDNL) approach is developed in accordance with the theoretical DNL framework ensuring vehicle conservation and FIFO. The first simulation experiment-based results are encouraging, indicating that the DDNL can contribute to improving the efficiency of applications where the monitoring of historical network-wide flows is required. Abbreviations: DDNL - Data Driven Network Loading; DNL - Dynamic Network Loading; DTA - Dynamic Traffic Assignment; ITS - Intelligent Transportation Systems; OD - Origin Destination; TTF - Travel Time Function; LTT - Linear Travel Time; DL - Demand level, Funding Agencies|Swedish Energy AgencySwedish Energy Agency [46963-1]

Dynamiska trafikmodeller förväntas i större utsträckning komplettera och på sikt helt eller delvis ersätta statiska trafikmodeller. Samtidigt blir trafikmätningar mer och mer tillgängliga, och utifrån dessa kan tidsvarierade estimeringar av flöden och hastighet över större områden tas fram. I Sverige används idag HBEFA för estimering av emissioner. HBEFA är en EU-gemensam modell som används i flera europeiska länder för beräkning av luftföroreningar och bränsleförbrukning. Detta projekt syftar till att ta fram en metod för tillämpning av HBEFA på trafikdata från mätningar och dynamiska trafikmodeller på ett sätt som är konsistent med den tillämpning av HBEFA som idag sker med statisk trafikdata. Projektet fokuserar främst på tillämpningar där lokala emissioner från vägtrafik är av intresse. Exempel på sådana tillämpningar är uppföljning, estimering och prediktering av luftkvalitet. Men även analys av förändring av utsläpp från vägtrafiken över tid, samt före/efter studier vid förändringar av trafikinfrastrukturen. Detta kräver att den tillämpade beräkningsmetodiken för utsläpp anpassas för att kunna dra nytta av den rikare information som dynamisk trafikdata innehåller.I HBEFA är skattning av trafiktillstånd centralt för estimering av emissioner. I denna studie har vi studerat och jämfört tre olika sätt att definiera trafiktillståndet i HBEFAstrafiksituationer nämligen baserat på: flöde (det som används i nuläget), hastighet och densitet. Flödesbaserade definitioner har en inbyggd begränsning i att de inte entydigt kan beskriva trafiksituationen, då lågt flöde kan innebära både låg trängsel och hög trängsel, beroende på hastighet. Detta är inget problem i nuvarande tillämpning av HBEFA med statisk trafikdata, då en förenklad beskrivning av det överbelastade fallet görs, som tillåter flöden över kapaciteten, men som då representerar en efterfrågan snarare än flöde. Undersökningarna i denna studieindikerar att en hastighetsbaserad definition av trafiktillstånd inte är

The introduction of automated vehicles (AVs) is commonly expected to improve different aspects of transportation. A long transition period is expected until AVs become prevalent on roads. During this period, different types of AVs with different driving logics will coexist along human driven vehicles. Using microscopic traffic simulation, this study investigates the range of potential impacts on traffic performance in terms of throughput and travel delays for different types of AVs and human driven vehicles on motorways. The simulation experiment includes scenarios with combinations of three different driving logics for AVs together with human driven vehicles at increasing penetration rates. The utilized AV driving logics represent the evolution of AVs, they were defined in the microscopic simulation tool Vissim and were created by modifying and extending the human driver behaviour models. The results of the simulation experiment show a decrease in vehicle throughput and significant effects on delay times when AVs with a more cautious driving logic are predominant. Overall, results show higher vehicle throughput and lower travel delays as AVs evolve to more advanced driving logics., Funding Agencies|Swedish Transport Administration (Trafikverket) [TRV 2016/20608, TRV 2019/27044]; European UnionEuropean Commission [H2020-ART-2016-2017, 723201]

The introduction of automated vehicles is expected to affect traffic performance. Microscopic traffic simulation offers good possibilities to investigate the potential effects of the introduction of automated vehicles. However, current microscopic traffic simulation models are designed for modelling human-driven vehicles. Thus, modelling the behaviour of automated vehicles requires further development. There are several possible ways to extend the models, but independent of approach a large problem is that the information available on how automated vehicles will behave is limited to todays partly automated vehicles. How future generations of automated vehicles will behave will be unknown for some time. There are also large uncertainties related to what automation functions are technically feasible, allowed, and actually activated by the users, for different road environments and at different stages of the transition from 0 to 100% of automated vehicles. This article presents an approach for handling several of these uncertainties by introducing conceptual descriptions of four different types of driving behaviour of automated vehicles (Rail-safe, Cautious, Normal, and All-knowing) and presents how these driving logics can be implemented in a commonly used traffic simulation program. The driving logics are also linked to assumptions on which logic that could operate in which environment at which part of the transition period. Simulation results for four different types of road facilities are also presented to illustrate potential effects on traffic performance of the driving logics. The simulation results show large variations in throughput, from large decreases to large increases, depending on driving logic and penetration rate., Funding Agencies|European UnionEuropean Union (EU) [H2020-ART-2016-2017, 723201]

In large urban areas, the estimation of vehicular traffic emissions is commonly based on the outputs of transport planning models, such as Static Traffic Assignment (STA) models. However, such models, being used in a strategic context, imply some important simplifications regarding the variation of traffic conditions, and their outputs are heavily aggregated in time. In addition, dynamic traffic flow phenomena, such as queue spillback, cannot be captured, leading to inaccurate modelling of congestion. As congestion is strongly correlated with increased emission rates, using STA may lead to unreliable emission estimations. The first objective of this paper is to identify the errors that STA models introduce into an emission estimation. Then, considering the type and the nature of the errors, our aim is to suggest potential solutions. According to our findings, the main errors are related to STA inability of accurately modelling the level and the location of congestion. For this reason, we suggest and evaluate the postprocessing of STA outputs through quasidynamic network loading. Then, we evaluate our suggested approach using the HBEFA emission factors and a 19 km long motorway segment in Stockholm as a case study. Although, in terms of total emissions, the differences compared to the simple static case are not so vital, the postprocessor performs better regarding the spatial distribution of emissions. Considering the location-specific effects of traffic emissions, the latter may lead to substantial improvements in applications of emission modelling such as dispersion, air quality, and exposure modelling., Funding Agencies|Swedish Energy AgencySwedish Energy Agency [38921-1]

Microscopic traffic simulation is an ideal tool for investigating the network level impacts of eco-driving in different networks and traffic conditions, under varying penetration rates and driver compliance rates. The reliability of the traffic simulation results however rely on the accurate representation of the simulation of the driver support system and the response of the driver to the eco-driving advice, as well as on a realistic modelling and calibration of the drivers behaviour. The state-of-the-art microscopic traffic simulation models however exclude detailed modelling of the driver response to eco-driver support systems. This paper fills in this research gap by presenting a framework for extending state-of-the-art traffic simulation models with sub models for drivers compliance to advice from an advisory eco-driving support systems. The developed simulation framework includes among others a model of drivers compliance with the advice given by the system, a gear shifting model and a simplified model for estimating vehicles maximum possible acceleration. Data from field operational tests with a full advisory eco-driving system developed within the ecoDriver project was used to calibrate the developed compliance models. A set of verification simulations used to illustrate the effect of the combination of the ecoDriver system and drivers compliance to the advices are also presented., Funding Agencies|European UnionEuropean Union (EU) [288611]; Swedish Energy AgencySwedish Energy Agency; European CommissionEuropean Commission Joint Research Centre

The mission of the H2020 CoEXist project is to enable mobility stakeholders to get “Automation-ready” – which CoEXist currently defines as conducting transport and infrastructure planning for connected and automated vehicles (CAVs) in the same comprehensive manner as for existing modes such as conventional vehicles, public transport, pedestrians, and cyclists, while ensuring continued support for existing modes on the same network. This definition will be fine-tuned through stakeholder engagement processes. The H2020 CoEXist project started in May 2017 and will run until April 2020. This paper introduces this project and covers its progress until January 2018, with a focus on the methodology of the “Automation-ready framework” that provides a planning framework for urban road authorities to prepare for the introduction of CAVs on the road network. The framework includes elements about strategic urban mobility planning for CAVs and a clear guide for urban transport planners with a list of concrete actions that cities can do now to plan for CAVs on their road network, 2018-06-01T16:04:39.378+02:00

The rapid growth of traffic congestion has led to an increased level of emissions and energy consumption in urban areas. Well designed infrastructure and traffic controllers along with more efficient vehicles and policy measures are required to mitigate congestion and thus reduce transport emissions. In order to evaluate how changes in the traffic system affect energy use and emissions, traffic analysis tools are used together with emission models. In large urban areas emission models mainly rely on aggregated outputs from traffic models, such as the average link speed and flow. Static traffic models are commonly used to generate inputs for emission models, since they can efficiently be applied to larger areas with relatively low computational cost. However, in some cases their underlying assumptions can lead to inaccurate predictions of the traffic conditions and hence to unreliable emission estimates. The aim of this paper is to investigate and quantify the errors that static modeling introduces in emission estimation and subsequently considering the source of those errors, to suggest and evaluate possible solutions. The long analysis periods that are commonly used in static models, as well as the static models’ inability to describe dynamic traffic flow phenomena can lead up to 40 % underestimation of the estimated emissions. In order to better estimate the total emissions, we propose the development of a post processing technique based on a quasi-dynamic approach, attempting to capture more of the excess emissions created by the temporal and spatial variations of traffic conditions.

Purpose Road traffic incidents cause delay, affect public safetyand the environment. The CEDR PRIMA project aims toextend practical guidance for traffic managers in pro-activeTraffic Incident Management (TIM) techniques to reduce theimpacts and associated costs of incidents.Methods The paper describes modelling methods used in theproject for assessing the effect of different management techniqueson incident duration and travel delay under various scenarios,including collision, adverseweather, heavy vehicle breakdownand other obstruction, assuming various management strategiesand generic impacts of novel technologies. Macroscopicsimulations of 178 variations of 13 basic scenarios have beenperformed using a flexible and computationally efficientmacroscopic queue model, results being verified by simulationusing a velocity-based Cell Transmission Model (CTM-v).Results The results of the two modelling methods are broadlyconsistent. While delays estimated by the two methods candiffer by up to 20%, this is small compared to the factor of30 range of modelled delays caused by incidents, dependingon their nature and circumstances, and is not sufficient toaffect general conclusions. Under the peak traffic conditionsassumed, the most important factor affecting delay is whetherrunning lanes can be kept open, but quick clearance of carriagewayis not always feasible.Conclusions Comparison of two very different modellingmethods confirms their consistency within the context of highlyscenario-dependent results, giving confidence in the results.Future research and data needs include further validation ofthe models, potential application to traffic flow and conflictprediction and incident prevention, and more complete andconsistent recording of incident timelines and impacts., Funding agencies; Conference of European Directors of Roads (CEDR); Highways England

Advanced Driver Assistance Systems (ADAS) offer the possibility of helping drivers to fulfill their driving tasks. Automated vehicles (AV) are capable of communicating with surrounding vehicles (V2V) and infrastructure (V2I) in order to collect and provide essential information about the driving environment. Studies have proved that automated driving have the potential to decrease traffic congestion by reducing the time headway (THW), enhancing the traffic capacity and improving the safety margins in car following. Despite different encouraging factors, automated driving raise some concerns such as possible loss of situation awareness, overreliance on automation and system failure. This paper aims to investigate the effects of AV on drivers behavior and traffic performance. A literature review was conducted to examine the AV effects on drivers behavior. Findings from the literature survey reveal that conventional vehicles (CV), i.e. human driven, which are driving close to a platoon of AV with short THW, tend to reduce their THW and spend more time under their critical THW. Additionally, driving highly AV reduce situation awareness and can intensify driver drowsiness, exclusively in light traffic. In order to investigate the influences of AV on traffic performance, a simulation case study consisting of a 100% AV scenario and a 100% CV scenario was performed using microscopic traffic simulation. Outputs of this simulation study reveal that the positive effects of AV on roads are especially highlighted when the network is crowded (e.g. peak hours). This can definitely count as a constructive point for the future of road networks with higher demands. In details, average density of autobahn segment remarkably improved by 8.09% during p.m. peak hours in the AV scenario, while the average travel speed enhanced relatively by 8.48%. As a consequent, the average travel time improved by 9.00% in the AV scenario. The outcome of this study jointly with the previous driving simu

The first Swedish 2+1 median barrier road was opened in 1998. The concept was to retrofit the standard existing two-lane 13 m paved width cross-section at 90 and 110 kph posted speed limit without widening. This design has one continuous lane in each direction, a middle lane changing direction every one to three kilometres with a median barrier separating the two traffic directions. Today over 2 700 km 2+1 median barrier roads are opened for traffic. AADTs vary from some 3 000 to 20 000 with an average just below 10 000 nowadays normally with 100 kph. The concept has lately been enhanced also to cover the existing 9 m paved width cross-section. The design concept is the same from a drivers viewpoint, one continuous lane in each direction with a middle lane changing direction and a separating median barrier. This is created by introducing a continuous median barrier and adding overtaking lanes within an overtaking strategy. The differences are the existence of 1+1-sections, less overtaking opportunities and a slightly more narrow cross-section. Some 15 projects are opened. The purpose of this paper is to summarize present knowledge on level-of-service issues as they are presented in Swedish design and assessment guidelines and to give an overview of field measurements and theoretical analytical and simulation studies supporting the recommendations.

This paper presents an investigation of capacity reduction in connection with roadwork zones. The paper presents a state-of-the-art description on roadwork effects on capacity. Based on the literature on this topic the most important parameters that should be incorporated in a Swedish capacity manual for the operation and maintenance roadwork are: the proportion of heavy traffic; lane width; number of closed lanes; closed road shoulder; proportion of commuter traffic; and length of roadwork zone. The paper presents a comparison of a composite model of correction factors from Germany, USA and Denmark and the Dutch model for computation of capacity reduction. The comparison show that the two models essentially gives the same results. Based on these results a model was developed. The model developed was validated using empirical data from a full scale test at the motorway network in Gothenburg. The throughput was measured in two cases during the morning and afternoon peak hour. The capacity for the normal site conditions was estimated based on traffic flow and speed data from the same site. The result shows that the empirically estimated capacity reduction is consistent with the reduction calculated with the new model for the different road work designs evaluated. The conclusion is that the model developed seems to be valid for capacity reduction estimations of roadworks on Swedish motorways but that more empirics are needed to ensure general validity.

Vägtrafiken är en stor källa till utsläpp av både lokalt, regionalt och globalt förorenande ämnen. Lokalt och regionalt förorenande ämnen så som partiklar, kolmonoxid, kolväten och kväveoxider har påverkan på både natur och människa, och hälsoskadliga effekter i stadsmiljö är välkända. Globalt förorenande ämnen från biltrafiken, främst koldioxid, är ett stort problem ur ett klimatperspektiv. Hälsovådliga utsläpp är främst intressanta ur ett luftkvalitetsperspektiv, det är då inte de faktiska utsläppen från fordon (emissioner) som är mest intressanta utan halten förorenande ämnen i luften. Halten av förorenande ämnen beror naturligtvis på emissioner, men också på utsläpp från andra källor och väder. Genom en förenklad värdering av denna typ av utsläpp, där man tar hänsyn till lokala variationer i spridning av emissioner i luften, värderas luftkvalitet i samhällsekonomiska kalkyler i Sverige direkt baserat på fordonsemissioner. Mer detaljerat beräknas spridning av emissioner när kommuner gör luftkvalitetsberäkningar i verktyget SIMAIR. Koldioxid värderas direkt utifrån sina emissioner i samhällsekonomiska kalkyler. Oavsett om syftet är att göra samhällsekonomiska kalkyler eller mer detaljerade luftkvalitetsberäkningar i SIMAIR används i Sverige vanligen utdata från statiska trafikmodeller, baserade på användarjämvikt, som indata till emissionsberäkningarna. En statisk nätutläggning tar inte hänsyn till variationer över tid, eller utbredning av köer i trafiknätverket. Även om mer detaljerade trafikanalyser ofta görs med dynamiska trafikmodeller i senare planeringsskeenden, är inte resultatet från dessa analyser direkt tillämpbara i de emissionsberäkningar som görs i Samkalk (det verktyg som vanligen används för samhällsekonomiska kalkyler i Sverige) eller i SIMAIR. I Sverige används främst emissionsmodellen HBEFA som är en databas med emissionsfaktorer. Emissionsfaktorerna beskriver utsläpp i gram per fordonskilometer för en given fordonstyp, vägklass och trafikförhåll

This paper presents a micro-simulation model that takes flared design of rural intersections into consideration. The intersection model is designed with input parameters that describe the geometric conditions of the flare. The behavior model includes both a traditional gap-acceptance sub-model and a passage model for modelling of vehicles’ possibility to pass other vehicles using the flare. The intersection model developed has been implemented in the traffic micro simulation model RuTSim. The gap-acceptance part of the model has been calibrated using data for stop and yield 3-way intersections. The validation was performed by using video recordings to calculate delay for the yield regulated intersection and time in queue and service time for the stop regulated intersection. The results from the validation simulations correspond well with the empirical validation data. The effect of the flare on delay has been studied by using 3 different intersection lay-outs and different levels of minor and major flow. The result shows that the delay is decreasing with increasing intersection radius.

In driving simulation, a scenario includes definitions of the road environment, the traffic situation, simulated vehicles’ interactions with the participant’s vehicle and measurements that need to be collected. The scenarios need to be designed in such a way that the research questions to be studied can be answered, which commonly imply exposing the participant for a couple of predefined specific situations that has to be both realistic and repeatable. This article presents an integrated algorithm based on Dynamic Actor Preparation and Automated Action Planning to control autonomous simulated vehicles in the simulation in order to generate predefined situations. This algorithm is thus able to plan driving actions for autonomous vehicles based on specific tasks with relevant contextual information as well as handling longitudinal transportation of simulated vehicles based on the contextual information in an automated manner. The conducted experiment shows that the algorithm is able to guarantee repeatability under autonomous traffic flow. The presented algorithm can benefit not only the driving simulation community, but also relevant areas, such as autonomous vehicle and in-vehicle device design by providing them with an algorithm for target pursue and driving task accomplishment, which can be used to design a human-vehicle cooperation system in the coming era of autonomous driving., TRENoP

To improve road safety on parts of the road network carrying low traffic volumes, road designs are proposed including single-lane road segments and periodic overtaking lanes. These roads have been proven to contribute to substantial benefits in terms of road safety. However, overtaking of slower vehicles is only possible on segments including an overtaking lane and not on the single-lane road segments. Driver and vehicle heterogeneity resulting in differences in desired speeds are consequently decisive for the traffic performance. Sufficient quality of service is relying on an appropriate design and distribution of single-lane segments and overtaking lanes. In this paper, we study the effect of the desired speed distribution on traffic performance on single-lane road segments. Expressions are derived for the travel time, delay and percent time spent following. The derived expressions link the desired speed distribution, the single-lane segment length and the traffic flow to the resulting traffic performance. The results are verified through comparison with measures based on microscopic traffic simulation. The conclusion is that there is a good agreement between derived measures and simulation results. The derived measures should therefore not only be of theoretical interest, but also of practical use to estimate traffic performance on single-lane road segments.

Dedicated bus lanes and bus streets have, in recent years, become common measures for prioritisation of public transport. By ensuring free path along routes, they increase average speed and travel time reliability of buses. However, a major drawback is that the total traffic capacities of the roads decrease. Hence, these measures are only suitable when the total traffic flow is low enough to allow for a reduction of lanes; if it is possible to reroute adjacent traffic; or if it is possible to extend the road with additional lanes. A supplementary priority measure could be to utilize dynamic bus lanes (also called intermittent bus lanes and bus lanes with intermittent priority). Dynamic bus lanes are only dedicated for buses when and where the buses need them, and otherwise open for all vehicles to use. At any given point, adjacent traffic is only permitted from using the dynamic bus lanes at the stretches where buses are in the vicinity. This report presents the results from a pre-study, investigating the potential that dynamic bus lanes could have as a priority measure for public transport in a Swedish context. Knowledge of situations in which dynamic bus lanes have the highest potential, and their implementation requirements is scarce. It is moreover uncertain how they would affect traffic safety, level of service and user experience. Two real world field tests have been conducted; one in Lisbon and one in Melbourne. The installation in Melbourne is now permanently applied for trams on one street. The field test in Lisbon was on the contrary not made permanent, although the results showed large benefits for buses and limited adverse effects on other vehicles. Dynamic bus lanes have also been investigated by means of traffic analysis and traffic simulation experiments. In general, these studies show that the effects on travel time for buses are in general positive and delays for other vehicles are limited. Results from example calculations in this pre-study show th, Busskörfält (körfält för fordon i linjetrafik m.fl.) och bussgator har under senare år blivit vanliga åtgärder för att prioritera kollektivtrafik. Genom att säkerställa fri väg längs med bussrutten så bidrar de till att öka bussarnas medelhastighet och restidssäkerhet. En nackdel är dock att den totala kapacitet på dessa vägar minskar. Dessa åtgärder är således endast lämpliga när trafikflödet är tillräckligt lågt för att klara en reducering av antalet körfält; när övrig trafik kan dirigeras om; eller när det finns möjlighet att utöka vägen med ytterligare körfält. En alternativ åtgärd kan vara att använda dynamiska busskörfält (internationellt även benämnt som ”intermittent bus lanes” och ”bus lanes with intermittent priority”). Dynamiska busskörfält är endast reserverade för kollektivtrafik när kollektivtrafiken behöver det och annars tillgängliga för alla fordon. Övrig trafik är endast förbjuden att använda det dynamiska busskörfältet när det finns en buss i närheten. Denna rapport presenterar en förstudie som undersökt vilken potential som dynamiska körfält har som åtgärd för prioritering av kollektivtrafik på svenska vägar. Kunskapen om i vilka trafiksituationer som dynamiska busskörfält har störst potential och vilka krav och begränsningar som finns för ett införande i Sverige är otillräcklig. Det är också oklart hur ett införande skulle påverka trafiksäkerhet, framkomlighet och användarna. Två fältförsök har genomförts; ett i Lissabon och ett i Melbourne. Installationen i Melbourne blev permanent och används för att prioritera spårvagnar på en vägsträcka. Fältförsöket i Lissabon blev inte permanent även om resultaten visade på stora vinster for bussarna och endast begränsad effekt på övrig trafik. Dynamiska busskörfält har även undersökts med hjälp av trafikmodellsanalyser och trafiksimuleringsexperiment. Studierna visar på att effekten på bussarnas restid är positiv och att fördröjningen för övriga fordon överlag är begränsad. Resultat från exempelberäkninga, PROVDYK

The global aim of the ecoDriver project is to increase the fuel efficiency by 20% by optimising the driver-powertrain-environment feedback loop and delivering effective advice to drivers. In the course of the project, field experiments will take place with a wide range of vehicles — e.g. cars, light trucks and vans, medium and heavy trucks and buses — covering both individual and collective transport. The last step of the project (Sub Project 5; SP5) is to scale up the results from these tests and analyse costs and benefits for a number of futurescenarios. The aim of SP5 is to predict the impact of the ecoDriver systems and solutions in the future, drawing on all the evaluations carried out in the project. With the results of SP5 it will be possible to make estimates about the costs and benefits of the suggested green driving support systems on a global (EU-27) level, both for society as a whole and for sub-groups like manufacturers and consumers. SP5 will construct a set of possible scenarios for the future depending on various road maps envisioned today. The predictions for future years will be made based on available data from within and outside of the project, and on advanced microscopic traffic modelling. SP5 takes the following steps to meet the objectives: Collect data needed for scaling up and developing scenarios Create a range of scenarios Assess the network implications of green driving support systems for future networks Predict the global impacts for a range of systems and scenarios Carry out a cost benefit analysis for a range of systems and scenarios This deliverable describes the data needs for each step. It also contains a description of the approaches proposed for the scenario building, the microscopic traffic simulations, the scaling up and the cost-benefit analysis., ecoDriver

Metoder för kapacitetsanalys (METKAP)

Detta VTI notat presenterar en beräkningsmetod för beräkning av förväntad kölängdoch restidsfördröjning för enfältiga vägavsnitt utan omkörningsmöjligheter. Metodenutvecklades 2001 och presenterades i ett PM. Bakgrunden till modellutvecklingen varatt dåvarande Vägverket (nu Trafikverket) planerade att införa så kallade 1+1-vägar, detvill säga, vägar med längre delsträckor utan omkörningsmöjlighet. Den utveckladeberäkningsmetoden har sedermera visat sig värdefull även vid framkomlighetsberäkningarför 2+1-vägar med varierande andel tvåfältsavsnitt och har använts vidframtagning av hastighetsflödessamband till Trafikverkets ”Effektsamband förvägtransportsystemet”.Metoden använder avsnittslängd, trafikflöde samt medelhastighet och standardavvikelsesom indata. Metoden är uppdelad på beräkning av effekter på grund av enstakalångsamtgående fordon samt effekter vid ”normal” hastighetsfördelning. Då mätdatasaknades vid modellutvecklingen jämfördes metoden med simuleringskörningar medden mikroskopiska trafiksimuleringsmodellen AIMSUN. Resultaten visar på en relativtgod korrelation men generellt så ger den analytiska metoden cirka 1,2 procent lägrerestidsfördröjning. En stor del av skillnaden mellan modellerna vid måttliga flöden börkunna härledas till det stokastiska inslaget i simuleringen. Det bör även påpekas attvarken den analytiska modellen eller trafiksimuleringsmodellen har kalibrerats ochvaliderats mot verkliga data för denna typ av väg. Skillnaden mellan modellerna innebärsåledes inte att den analytiska modellen självklart är den som avviker från verkligheten., This VTI report presents a method for calculating expected queue length and travel timedelay on one lane road sections without overtaking possibilities. The method wasdeveloped 2001 and presented in a working paper. The background for the modeldevelopment was that the Swedish Road Administration (now the Swedish TransportAdministration) planned to build so called 1+1 roads, i.e. roads with longer sectionswithout overtaking possibilities. The method developed has later on also shown to bevaluable for level of service calculations of 2+1 roads with varying share of two lanesections and for developing speed-flow relationships for the Administration’s ”Effectcalculations for road facilities”.The method uses section length, traffic flow, average speed and standard deviation asinput. The method is divided with respect to calculation of effects due to single slowrunningvehicles and effects at “normal” speed distribution. Since no data wereavailable when the model was developed, the model results were instead compared totraffic simulations with the microscopic traffic simulation model AIMSUN. The resultsshow a good correlation but the analytical model gives in general approximately 1.2 percent lower travel time delay. The differences can probably partly be explained by thestochastic parts of the simulation model. One should also remember that neither theanalytical model nor the simulation model has been calibrated and validated with realdata for this type of roads. Thus, the differences between the models do not necessaryimply that the analytical model is the one deviating from reality.

Autonomous vehicles can be used to create realistic simulations of surrounding vehicles in driving simulators. However, the use of autonomous vehicles makes it difficult to ensure reproducibility between subjects. In this paper, an effort is made to solve the problem by combining autonomous vehicles and controlled events, denoted plays. The aim is to achieve the same initial play conditions for each subject, since the traffic situation around the subject will be dependant upon each subject's actions while driving in the autonomous traffic. This paper presents an algorithm that achieves the transition from autonomous traffic to a predefined start condition for a play. The algorithm has been tested in the VTI driving simulator III with promising results. In most of the cases the algorithm could reconstruct the specified start condition and conduct the transition from autonomous to controlled mode in a non-conspicuous way. Some problems were observed regarding moving unwanted vehicles away from the closest area around the simulator vehicle, and this part of the algorithm has to be enhanced. The experiment also showed that the controlled every-day life traffic normally used in the VTI driving simulator makes subjects drive faster than in autonomous traffic., Funding agencies|Swedish Road Administration, Transport Telematics Sweden||INRETS

Roundabouts have become a more common type of intersection in Sweden over the last 30 years. In order to evaluate the roundabout level-of-service both analytical models and simulation models are being used. Analytical traffic models for intersections, such as the Swedish capacity model Capcal, has difficulties estimating the level-of-service of a roundabout if there are pedestrians and cyclists at crossings located close to the roundabout. It is well known that a crossing located after a roundabout exit can cause an up-stream blocking effect that affects the performance of the roundabout. But how the upstream blocking effect depends on the different flows of vehicles and pedestrians is not known. In this paper an existing analytical model by Rodegerdts and Blackwelder has been investigated and compared to simulations in VISSIM and measurements from Swedish roundabouts. The purpose of this investigation is to examine if the model by Rodegerdts and Blackwelder is suitable for implementing into existing analytical models such as Capcal. The results show that the model by Rodegerdts and Blackwelder can estimate if a capacity loss will occur, but the magnitude of this loss is more difficult to evaluate. The conclusion and recommendation is that the model by Rodegerdts and Blackwelder should be implemented into the Swedish capacity model Capcal. The model by Rodegerdts and Blackwelder is to be used as a warning system if the results in Capcal are too uncertain to use for analysis of the roundabout performance.

Driving simulators and microscopic traffic simulation are important tools for making evaluations of driving and traffic. A driving simulator is de-signed to imitate real driving and is used to conduct experiments on driver behavior. Traffic simulation is commonly used to evaluate the quality of service of different infrastructure designs. This thesis considers a different application of traffic simulation, namely the simulation of surrounding vehicles in driving simulators. The surrounding traffic is one of several factors that influence a driver's mental load and ability to drive a vehicle. The representation of the surrounding vehicles in a driving simulator plays an important role in the striving to create an illusion of real driving. If the illusion of real driving is not good enough, there is an risk that drivers will behave differently than in real world driving, implying that the results and conclusions reached from simulations may not be transferable to real driving. This thesis has two main objectives. The first objective is to develop a model for generating and simulating autonomous surrounding vehicles in a driving simulator. The approach used by the model developed is to only simulate the closest area of the driving simulator vehicle. This area is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to a microscopic model which includes sub-models for driving behavior, while vehicles in the outer regions are updated according to a less time-consuming mesoscopic model. The second objective is to develop an algorithm for combining autonomous vehicles and controlled events. Driving simulators are often used to study situations that rarely occur in the real traffic system. In order to create the same situations for each subject, the behavior of the surrounding vehicles has traditionally been strictly controlled. This often leads to less realistic surrounding traffic. The algorithm developed makes it possib

Driving simulators are used to conduct experiments on for example driver behavior, road design, and vehicle characteristics. The results of the experiments often depend on the traffic conditions. One example is the evaluation of cellular phones and how they affect driving behavior. It is clear that the ability to use phones when driving depends on traffic intensity and composition, and that realistic experiments in driving simulators therefore has to include surrounding traffic. This thesis describes a model that generates and simulates surrounding vehicles for a driving simulator. The proposed model generates a traffic stream, corresponding to a given target flow and simulates realistic interactions between vehicles. The model is built on established techniques for time-driven microscopic simulation of traffic and uses an approach of only simulating the closest neighborhood of the driving simulator vehicle. In our model this closest neighborhood is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to advanced behavioral models while vehicles in the outer regions are updated according to a less time-consuming model. The presented work includes a new framework for generating and simulating vehicles within a moving area. It also includes the development of enhanced models for car-following and overtaking and a simple mesoscopic traffic model. The developed model has been integrated and tested within the VTI Driving simulator III. A driving simulator experiment has been performed in order to check if the participants observe the behavior of the simulated vehicles as realistic or not. The results were promising but they also indicated that enhancements could be made. The model has also been validated on the number of vehicles that catches up with the driving simulator vehicle and vice versa. The agreement is good for active and passive catch-ups on rural roads and for passive catch-ups on freeways, but less good fo