| 1. |
- Adesiyun, Adewole, et al.
(författare)
-
Review and Evaluation of NRAs : Deliverable D2
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Connected and Automated Driving (CAD) is an important area of digital technology that will bring disruption to individuals, economies, and societies. Most forms of CAD require some level of infrastructure support for their safe operation. Additional infrastructure and services to support CAD have the potential to improve safety even further, and to bring other benefits such as increased efficiency or reduced congestion. However, the infrastructure requirements from Original Equipment Manufacturer (OEMs) are not always clear, and it is difficult for National Road Authorities (NRAs) to predict and plan for the future levels of support needed for CAD given rapidly evolving technology and uncertain projections of future CAD demand. In addition, there is also a need for better dialogue among NRAs, OEMs and service providers to articulate those requirements and to define a roadmap and responsibilities for achieving safe and smart roads through CAD.The aim of DiREC is to establish a CAV Readiness Framework and a set of toolkits dedicated to CAVs (Connected and Autonomous Vehicles) that incorporates a wide range of components that affect CAD and the ability of highway infrastructure to support it. These components include machine readability of physical infrastructure, digital services, connectivity, in addition to aspects such as governance of the infrastructure and services, and legal and regulatory requirements. Together these components influence the ability of the NRA to become a digital road operator. The DiREC project will thus provide a framework for NRAs, service providers and OEMs to support CAD. It will consolidate and combine standards, research, and recommendations from other projects and extend research into new areas such as creating a common vision for digital twins among NRAs, understanding connectivity and connectivity requirements to support digital services and analysing how these can be met, reviewing the quality management processes around digital data, and documenting existing legal and regulatory frameworks in all areas relating to CAD.
|
|
| 2. |
- Borsos, Attila, et al.
(författare)
-
Are collision and crossing course surrogate safety indicators transferable? A probability based approach using extreme value theory
- 2020
-
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 143
-
Tidskriftsartikel (refereegranskat)abstract
- In order to overcome the shortcomings of crash data a number of surrogate measures of safety have been developed and proposed by various researchers. One of the most widely used temporal indicators is time-to-collision (TTC) which requires the road users to be on a collision course. Road users that are strictly speaking not on a collision course actually might behave and take evasive actions as if they were, thus indicating that such near-miss situations might also be relevant for safety analysis. Taking that into account, a more flexible indicator T2, which does not require the two vehicles to be on a collision course, describes the expected time for the second road user to arrive at the conflict point. Recently extreme value theory (EVT) offering two approaches, block maxima (BM) and Peak over Threshold (POT), has been applied in combination with surrogate indicators to estimate crash probabilities. Most of this research has focused on testing BM and POT as well as validating various surrogate safety indicators by comparing model estimates to actual crash frequencies. The comparison of collision course indicators with indicators including crossing course interactions and their performance using EVT has not been investigated yet. In this study we are seeking answers to under what conditions these indicators perform better and whether they are transferable. Using data gathered at a signalized intersection focusing on left-turning and straight moving vehicle interactions our analysis concluded that the two indicators are transferable with stricter threshold values for T2 and that POT gives more reasonable results.
|
|
| 3. |
|
|
| 4. |
- Farah, Haneen
(författare)
-
Age and Gender Differences in Overtaking Maneuvers on Two-Lane Rural Highways
- 2011
-
Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2248, s. 30-36
-
Tidskriftsartikel (refereegranskat)abstract
- For decades researchers have been pointing out significant differences in the driving behavior between young and old and between male and female drivers. There are many studies concerning age and gender differences in risk perception, traffic accident involvement, traffic violations, alcohol consumption, and risky driving. However, little effort has been focused on studying the behavioral differences in overtaking maneuvers on two-lane highways. A considerable percentage of the fatal accidents on two-lane highways is directly related to overtaking maneuvers. Therefore, the main focus of this study is to understand better the overtaking behavior of different drivers classified by their age and gender. Data on the overtaking behavior of 100 drivers were collected with an interactive driving simulator. Several scenarios of two-lane rural highways with different geometric and traffic conditions were developed. The results show interesting and significant differences in the overtaking behavior of drivers depending on their age and gender. These differences are mainly in the frequency of overtaking maneuvers, overtaking time duration, following distances, critical overtaking gaps, and desired driving speeds. Geometric and traffic conditions were also found to have a significant impact on drivers' overtaking behavior. The findings of this study contribute to the understanding of the overtaking behavior of different groups of drivers and thus have implications for road safety intervention programs and the development of effective risk reduction strategies adapted and targeted for different age and gender groups.
|
|
| 5. |
- Farah, Haneen, et al.
(författare)
-
Do cooperative systems make drivers' car-following behavior safer?
- 2014
-
Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 41, s. 61-72
-
Tidskriftsartikel (refereegranskat)abstract
- The main goal of in-vehicle technologies and co-operative services is to reduce congestion and increase traffic safety. This is achieved by alerting drivers on risky traffic conditions ahead of them and by exchanging traffic and safety related information for the particular road segment with nearby vehicles. Road capacity, level of service, safety, and air pollution are impacted to a large extent by car-following behavior of drivers. Car-following behavior is an essential component of micro-simulation models. This paper investigates the impact of an infrastructure-to-vehicle (I2V) co-operative system on drivers' car-following behavior. Test drivers in this experiment drove an instrumented vehicle with and without the system. Collected trajectory data of the subject vehicle and the vehicle in front, as well as socio-demographic characteristics of the test drivers were used to estimate car-following models capturing their driving behavior with and without the I2V system. The results show that the co-operative system harmonized the behavior of drivers and reduced the range of acceleration and deceleration differences among them. The observed impact of the system was largest on the older group of drivers.
|
|
| 6. |
- Farah, Haneen, et al.
(författare)
-
Drivers’ Decision Making of Overtaking Strategies of Cyclists on Rural Roads–A Driving Simulator Experiment
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cyclists’ involvement in road crashes has not been improving with the same magnitude as other modes of transport. Especially, the interactions between cyclists and motorized traffic can end up with the most severe types of crashes. To improve the safety of these interactions, a thorough understanding of road users’ decisions and behaviours is first needed. In this study, the authors focus on drivers’ overtaking manoeuvres of cyclists on rural roads. The main objective of this study is to develop a model that can predict drivers’ decisions whether to perform a flying or an accelerative overtaking manoeuvre when approaching a cyclist in the presence of oncoming traffic. A driving simulator study was designed to collect trajectory data of the overtaking vehicle, cyclist, and oncoming traffic. Drivers’ characteristics data was collected using surveys. In total, 37 drivers participated, each of them performing 7 overtaking manoeuvres. Out of 259 overtaking manoeuvres, 168 were flying and 91 were accelerative. Two binary logistic regression models were developed and estimated. In the two models, the time-to-collision and the driver’s speed significantly affect the decision on the overtaking manoeuvre type. In the first model, the correlations among the observations of the same driver were captured through the drivers’ characteristics. In the second model, these correlations were captured through a driver specific error term. The overall performance is 87.7% and 94.9% for the first and second models, respectively. In the paper the authors discuss the usability of each model for policy making, system design, and system evaluation.
|
|
| 7. |
- Farah, Haneen, et al.
(författare)
-
Drivers' Irrationality in Evaluating Risks on Two-Lane Highways
- 2012
-
Ingår i: Journal of Transportation Safety and Security. - : Informa UK Limited. - 1943-9962 .- 1943-9970. ; 4:1, s. 67-82
-
Tidskriftsartikel (refereegranskat)abstract
- Head-on collisions on two-lane rural highways might result from failed passing maneuvers. This paper investigates the hypothesis that drivers do not always estimate the required passing gap correctly, and their decision to overtake is made under a particular, even if small, probability that a crash will occur; this is the associated risk. The research investigates drivers’ irrationality in evaluating the risks of different passing gaps and, develops a risk-taking measure. This measure provides a tool for classifying drivers into different groups: risky drivers, partially cautious, and cautious drivers. A comparison of the socio-demographic averages, driving style, and crash history parameters for these groups showed significant differences.The measure developed can be used for risk evaluation and as a measure of safety. It further provides a tool for classifying drivers into groups based on their risk-taking characteristics. This is particularly useful for safety education programs.
|
|
| 8. |
- Farah, Haneen, et al.
(författare)
-
Evaluation of the effect of cooperative infrastructure-to-vehicle systems on driver behavior
- 2012
-
Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 21:1, s. 42-56
-
Tidskriftsartikel (refereegranskat)abstract
- In-vehicle technologies and co-operative services have potential to ease congestion problems and improve traffic safety. This paper investigates the impact of infrastructure-to-vehicle co-operative systems, case of CO-OPerative SystEms for Intelligent Road Safety (COOPERS), on driver behavior. Thirty-five test drivers drove an instrumented vehicle, twice, with and without the system. Data related to driving behavior, physiological measurements, and user acceptance was collected. A macro-level approach was used to evaluate the potential impact of such systems on driver behavior and traffic safety. The results in terms of speeds, following gaps, and physiological measurements indicate a positive impact. Furthermore, drivers' opinions show that the system is in general acceptable and useful.
|
|
| 9. |
- Farah, Haneen, et al.
(författare)
-
Guest Editorial Introduction to the Special Issue on Deployment of Connected and Automated Vehicles in Mixed Traffic Environment and the Implications on Traffic Safety and Efficiency
- 2023
-
Ingår i: IEEE transactions on intelligent transportation systems (Print). - : IEEE. - 1524-9050 .- 1558-0016. ; 24:6, s. 6432-6435
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 10. |
- Farah, Haneen, et al.
(författare)
-
Impact of Cooperative Systems on Drivers' Car-Following Behavior
- 2012
-
Ingår i: TRB 91st Annual Meeting Compendium of Papers.
-
Konferensbidrag (refereegranskat)abstract
- In-vehicle technologies and co-operative services are designed to ultimately reduce congestion and increase traffic safety. This paper investigates the impact of an infrastructure-to-vehicle co-operative system on drivers’ car-following behavior. Car following behavior, which describes the behavior of a vehicle while following the vehicle in front of it, has a significant impact on traffic performance, safety, and air pollution. In addition, it is an essential component of microsimulation models. Twenty nine test drivers drove an instrumented vehicle twice with and without the system. Trajectory data of each vehicle and the vehicle in front were collected. Car-following models were estimated for both cases, with and without the system, and the results of the two models were compared. The results show that co-operative systems have a positive impact on drivers’ car-following behavior. The system harmonizes the driving behavior of drivers and reduces the range of acceleration and deceleration differences among them. The impact of the system is larger on older drivers compared to younger drivers.
|
|
| 11. |
|
|
| 12. |
- Farah, Haneen, et al.
(författare)
-
Modeling Automated Driving in Microscopic Traffic Simulations for Traffic Performance Evaluations : Aspects to Consider and State of the Practice
- 2023
-
Ingår i: IEEE transactions on intelligent transportation systems (Print). - : IEEE. - 1524-9050 .- 1558-0016. ; 24:6, s. 6558-6574
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 13. |
- Farah, Haneen
(författare)
-
Modeling drivers' passing duration and distance in a virtual environment
- 2013
-
Ingår i: IATSS Research. - : Elsevier BV. - 0386-1112. ; 37:1, s. 61-67
-
Tidskriftsartikel (refereegranskat)abstract
- In many countries two-lane rural highways constitute a large proportion of the road network. One of the most fatal crash types is head-on collisions. Some of these head-on collisions are caused by failed passing maneuvers, when a driver does not succeed to complete the pass safely.Detailed observation of drivers' passing behavior in reality is difficult and complex. This study uses a driving simulator to collect detailed data on drivers' passing behavior. Using this data, empirical models explaining passing duration and distance were developed and estimated. These models take into account the impact of the traffic conditions, geometric design, and drivers' socio-demographic characteristics.The results revealed that the passing duration and distance of older drivers are significantly higher than younger drivers. The passing duration and distance are significantly affected by the traffic related variables of the subject, front, and opposing vehicles. The duration and passing distance increase when drivers initiate the passing maneuvers from a larger following distance from the front vehicle. Driver gender, road curvature, and types of front and opposing vehicles were not found to have a statistically significant impact on the passing duration and distance.The time that takes the driver to arrive to the critical position, or the point of no return, from the moment of start passing is equal to 41.7% of the time needed to complete the passing maneuver, higher compared to the value suggested by AASHTO (33%). This has important implications on safety.The main contribution of this paper is in the empirical models developed for passing duration and distance which highlights the factors that affect drivers' passing behavior and can be used to enhance the passing models in simulation programs.
|
|
| 14. |
- Farah, Haneen, et al.
(författare)
-
Modelling overtaking strategy and lateral distance in car-to-cyclist overtaking on rural roads: A driving simulator experiment
- 2019
-
Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 63, s. 226-239
-
Tidskriftsartikel (refereegranskat)abstract
- The involvement of cyclists in road crashes has not been decreasing with the same magnitude as the involvement of other road users. In particular, the interactions between cyclists and motorized traffic can lead to high-severity crashes. To improve the safety of these interactions, a thorough understanding of road user behaviour is first needed. In this study, we focused on drivers overtaking cyclists on rural roads. The two main objectives of this study were to develop models that predicted: (a) drivers’ decisions to perform either a flying or an accelerative overtaking manoeuvre in the presence of oncoming traffic, and (b) the lateral comfort distance that drivers maintain from cyclists during the overtaking. A driving simulator study was designed to assess driver decision-making during the overtaking. The 37 drivers who participated in the study each performed seven overtaking manoeuvres with oncoming traffic. Out of the 259 overtaking manoeuvres, 168 were flying and 91 were accelerative. Binary logistic-regression models with mixed effects predicted the type of overtaking strategy (flying or accelerative). Driving speeds were found to significantly affect the strategy. The overall performance of the models predicting the strategy was 85–90%. Models were also developed for predicting the lateral comfort distance. The results show that the lateral comfort distance is mostly affected by the longitudinal distance between the subject vehicle and the oncoming vehicle, the longitudinal distance between the subject vehicle and the cyclist, and the presence of an oncoming vehicle—as well as by the drivers’ characteristics (sensation seeking in flying overtaking manoeuvres and ordinary violations in accelerative manoeuvres). The root mean square error, which was used to assess the performance of the models, ranged from 0.56 to 0.62. In conclusion, the models predicting the overtaking strategy performed reasonably well, while the models predicting lateral distance did not provide accurate predictions. The models predicting overtaking strategy may support (1) the development and evaluation of active safety systems, (2) the design of automated driving, and (3) policy making.
|
|
| 15. |
- Farah, Haneen, et al.
(författare)
-
Passing behavior on two-lane highways
- 2010
-
Ingår i: Transportation Research Part F. - : Elsevier BV. - 1369-8478 .- 1873-5517. ; 13:6, s. 355-364
-
Tidskriftsartikel (refereegranskat)abstract
- Two-lane highways make up a substantial proportion of the road network in most of the world. Passing is among the most significant driving behaviors on two-lane highways. It substantially impacts the highway performance. Despite the importance of the problem, few studies attempted to model passing behavior. In this research, a model that attempts to capture both drivers' desire to pass and their gap acceptance decisions to complete a desired passing maneuver is developed and estimated using data on passing maneuvers collected with a driving simulator. Sixteen different scenarios were used in the experiment in order to capture the impact of factors related to the various vehicles involved, the road geometry and the driver characteristics in the model. A passing behavior model is developed that includes choices in two levels: the desire to pass and the decision whether or not to accept an available passing gap. The probability to complete a passing maneuver is modeled as the product of the probabilities of a positive decision on both these choices. The estimation results show that modeling the drivers' desire to pass the vehicle in front has a statistically significant contribution in explaining their passing behavior. The two sub-models incorporate variables that capture the impact of the attributes of the specific passing gap that the driver evaluates and the relevant vehicles, the geometric characteristics of the road section and the driver characteristics and account for unobserved heterogeneity in the driver population.
|
|
| 16. |
- Farah, Haneen, et al.
(författare)
-
Risk Evaluation by Modeling of Passing Behavior on Two-Lane Rural Highways
- 2009
-
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 41:4, s. 887-894
-
Tidskriftsartikel (refereegranskat)abstract
- Passing maneuver on rural two-lane highways is a complex task, which has a significant effect on capacity, level of service and safety. The maneuver is conditioned on the gap between two successive vehicles on the opposing lane. The minimum time to collision, defined as the remaining gap between the passing vehicle and the oncoming vehicle at the end of the passing process, expresses a measure of the risk involved in the passing maneuver. This paper develops a model that explains the minimum time to collision. The model formulation is based on the analysis of drivers' passing decisions on two-lane rural highways using an interactive driving simulator. The simulator enables the collection of vehicle speeds and positions for different road and traffic scenarios. In addition to the driver simulator, participants responded to a questionnaire which collected information about their socio-demographic characteristics. The composed dataset was analyzed and processed to develop a model that predicts the risk associated with the passing behavior. Tobit regression models were found to be more suitable, in comparison to ordinary least square models and Hazard-based Duration models. The explanatory variables tested represent road geometry, traffic conditions and drivers' characteristics. It was found that while the traffic related variables had the most important effect on the measure of risk chosen, factors related to the geometric design and the driver characteristics also had a significant contribution.
|
|
| 17. |
- Koutsopoulos, Haris N., et al.
(författare)
-
Latent Class Model for Car Following Behavior
- 2012
-
Ingår i: Transportation Research Part B. - : Elsevier BV. - 0191-2615 .- 1879-2367. ; 46:5, s. 563-578
-
Tidskriftsartikel (refereegranskat)abstract
- Car-following behavior, which describes the behavior of a vehicle while following the vehicle in front of it, has a significant impact on traffic performance, safety, and air pollution. In addition, car-following is an essential component of micro-simulation models. Over the last decade the use of microscopic simulation models as a tool for investigating traffic systems, ITS applications, and emission impacts, is becoming increasingly popular. The paper presents a flexible framework for modeling car-following behavior that relaxes some limitations and assumptions of the most commonly used car following models. The proposed approach recognizes different regimes in driving such as car-following, free-flow, emergency stopping, and incorporates different decisions in each regime, such as acceleration, deceleration, and do-nothing depending on the situation. A case study using NGSIM vehicle trajectory data is used to illustrate the proposed model structure. Statistical tests suggest that the model performs better than previous models.
|
|
| 18. |
- Mwesige, Godfrey, et al.
(författare)
-
A Model and Its Applications for Predicting Passing Rate at Passing Zones on Two-Lane Rural Highways
- 2016
-
Ingår i: Journal of transportation engineering. - : American Society of Civil Engineers (ASCE). - 0733-947X .- 1943-5436. ; 142:3
-
Tidskriftsartikel (refereegranskat)abstract
- Passing zones are designed to provide sufficient sight distance for fast vehicles to pass safely slow vehicles and contribute to operational efficiency of two-lane highways. However, lack of suitable models to predict passing rate and capacity has made it difficult to quantify operational benefits of passing zones. In this paper, a model is proposed to predict passing rate in the subject direction at passing zones using traffic and geometric factors. The model is developed based on speed and passing data collected at 19 passing zones in Uganda using pneumatic tube classifiers and video recordings. Findings show that passing rates depend on the length of the passing zone, absolute vertical grade, traffic volume in two travel directions, directional split, 85th percentile speed of free-flow vehicles and percent heavy vehicles in the subject direction. The peak passing rate also referred to as the passing capacity occurs at 200, 220, and 240 vehicles/h in the subject direction for 50/50, 55/45, and 60/40 directional splits, respectively. The model could potentially be applicable in planning, design, and safety evaluation of two-lane rural highways.
|
|
| 19. |
|
|
| 20. |
- Mwesige, Godfrey, 1978-, et al.
(författare)
-
Capacity and Safety of Passing Zones on Two-Lane Rural Highways : A Review of Theory and Practice
- 2014
-
Ingår i: Journal of Traffic and Logistics Engineering. - : EJournal Publishing. - 2301-3680. ; 2:2
-
Tidskriftsartikel (refereegranskat)abstract
- Passing zones are primary operational features of two-lane rural highways where fast vehicles pass slow vehicles using a lane reserved for traffic in opposing direction. The operation of these zones has an effect on the overall safety of two-lane rural highways especially when passing opportunities reduce considerably at higher flows. This paper presents a review on capacity and safety of passing zones on two-lane rural highways. Despite stated importance of passing zones to the operational performance of two-lane rural highways, passing zone capacity has not been estimated and its impact on safety is still not known. Safety evaluations mainly compare adequacy of design and marking passing sight distances to complete passing maneuvers as well as parameters derived from the passing process namely; passing duration, speed difference between passing and passed vehicles, and clearance between passing and opposing vehicle at the end of the maneuver. There is need for further research to address gaps in current capacity and safety evaluation methods of two-lane rural highways with focus on; (a) development of robust passing rate models for individual passing zones based on geometric, environmental and traffic factors, (b) estimation of passing zone capacity, (c) development of criteria to evaluate capacity and safety of passing zones for use by policy makers, planners and transportation engineers and (d) application of passing zone capacity to evaluate rural highway sections with several passing zones.
|
|
| 21. |
- Mwesige, Godfrey, et al.
(författare)
-
Effect of passing zone length on operation and safety of two-lane rural highways in Uganda
- 2017
-
Ingår i: IATSS RESEARCH. - : ELSEVIER SCI LTD. - 0386-1112. ; 41:1, s. 38-46
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a methodology to assess the effect of the length of passing zone on the operation and safety of two-lane rural highways based on the probability and the rate of passing maneuvers ending in a no-passing zone. The methodology was applied using observed passing maneuver data collected with tripod-mounted camcorders at passing zones in Uganda. Findings show that the rate at which passing maneuvers end in a no-passing zone increases with traffic volume and unequal distribution of traffic in the two directions, absolute vertical grade, and percent of heavy vehicles in the subject direction. Additionally, the probability of passing maneuvers ending in a no-passing zone reaches 0.50 when the remaining sight distance from the beginning of the passing zone is 245 m for passenger cars or short trucks (2-3 axles), and 300 m for long trucks (4-7 axles) as the passed vehicles. These results suggest policy changes in design and marking of passing zones to enhance safety and operation of two-lane rural highways. (C) 2016 International Association of Traffic and Safety Sciences.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Mwesige, Godfrey, et al.
(författare)
-
Risk appraisal of passing zones on two-lane rural highways and policy applications
- 2016
-
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 90, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- Passing on two-lane rural highways is associated with risks of head-on collision resulting from unsafe completion of passing maneuvers in the opposite traffic lane. In this paper, we explore the use of time to-collision (ITC) as a surrogate safety measure of the risk associated with passing maneuvers. Logistic regression models to predict the probability to end the passing maneuver with TTC less than 2 or 3 s-threshold were developed with the time-gap from initiation of the maneuver to arrival of the opposite vehicle (effective accepted gap), and the passing duration as explanatory variables. The data used for model estimation was collected using stationary tripod-mounted camcorders at 19 passing zones in Uganda. Results showed that passing maneuvers completed with TTC less than 3 s are unsafe and often involved sudden speed reduction, flashing headlights, and lateral shift to shoulders. Model sensitivity analysis was conducted for observed passing durations involving passenger cars or short trucks (2-3 axles), and long trucks (4-7 axles) as the passed vehicles for 3 s TTC-threshold. Three risk levels were proposed based on the probability to complete passing maneuvers with TTC less than 3 s for a range of opposite direction traffic volumes. Applications of the results for safety improvements of two-lane rural highways are also discussed. (C) 2016 Elsevier Ltd. All rights reserved.
|
|
| 25. |
|
|
| 26. |
- Pezo Silvano, Ary, 1975-
(författare)
-
Advancing Traffic Safety : An evaluation of speed limits, vehicle-bicycle interactions, and I2V systems
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the introduction of motor vehicles, the number of fatalities and accidents has been a concern for society.The number of fatalities on roads is amongst the most common causes of mortality worldwide (WHO, 2015).Even in industrialized countries the number of fatalities remains unacceptable. Therefore, in the last decades, anumber of approaches have emerged to support and boost traffic safety towards a system free from fatalities andserious impairment outcomes. ‘Sustainable Safety’ and ‘Vision Zero’ are well-known examples aiming to avoidfatalities within the traffic system and reduce injury severity when a traffic accident is inevitable. However, thenumber of fatalities and seriously injured accidents are still relatively high. More specifically, vulnerable roadusers remain involved in fatal and serious accidents even in industrialized countries. Therefore, further advancesin traffic safety studies are needed. This thesis aims at evaluating the impact of road characteristics, traffic rulesand information provision towards a safer traffic system. The thesis is composed of five scientific papers whichsummarizes the main contributions of this work.
|
|
| 27. |
- Silvano, Ary P., 1975-, et al.
(författare)
-
Free flow speed estimation : A probabilistic, latent approach. Impact of speed limit changes and road characteristics
- 2020
-
Ingår i: Transportation Research Part A. - : Elsevier Ltd. - 0965-8564 .- 1879-2375. ; 138, s. 283-298
-
Tidskriftsartikel (refereegranskat)abstract
- The estimation of the free flow speed (FFS) distribution is important for capacity analysis, determination of the level-of-service, and setting speed limits. Subjective time headway thresholds have been commonly used to identify vehicles travelling under free flow speed conditions i.e., vehicles whose speeds are not influenced by the vehicle in front. Since, the headway a driver operates under the free flow state is subjective and varies from driver to driver, such approaches can introduce biases in the FFS estimation. Therefore, in this paper a parametric probabilistic latent approach is proposed based on discrete choice utility theory to estimate the FFS distribution on urban roads and simultaneously the probability that drivers perceive their state as constrained by the vehicle in front. This methodology is used to estimate the impacts of road characteristics and Posted Speed Limit (PSL) changes on the FFS distribution using an extensive dataset of speed observations from urban roads with varying characteristics. The results show that the simultaneous estimation of the free flow speed distribution and the state the driver is in (e.g., free or constrained) is feasible. The analysis indicates that the FFS is influenced by several road characteristics such as land use, on-street parking and the presence of sidewalks. The PSL change impacts not only the distribution of the free flow vehicles but also the speed distribution of the constrained vehicles. The constrained probabilities vary depending on the PSL change with higher probabilities for lower speed limits.
|
|
| 28. |
- Silvano, Ary P., 1975-
(författare)
-
Impacts of Speed Limits and Information Systems on Speed Choice from a Safety Perspective.
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Driving a vehicle is considered a demanding task in a complex dynamic environment. For instance, driving a vehicle on urban roads, where motorized vehicles meet vulnerable road users (VRUs) creates a multifaceted environment with difficult trade-offs and interactions. Additionally, in-vehicle technology developments are being introduced to ease drivers with the driving task. However, these developments are changing “traditional” driving increasing drivers’ response in terms of information processing, thus making the driving task more demanding in some respects. Therefore, the aim of the present research is to further investigate drivers’ speed choice under varying traffic management regulations and in-vehicle warning systems.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
- Toledo, Tomer, et al.
(författare)
-
Alternative Definitions of Passing Critical Gaps
- 2011
-
Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2260, s. 76-82
-
Tidskriftsartikel (refereegranskat)abstract
- A substantial proportion of the road network in most countries consists of two-lane highways. Available gaps for passing are a fundamental element in the operation of such highways. Providing passing opportunities is important for reducing the formation of vehicle platoons in the traffic flow, increasing the level of service, and improving safety. Passing opportunities also affect fuel consumption and emissions. Despite the importance of passing on two-lane highways, few studies have focused on exploring passing gap definitions when modeling passing behavior. Research was done to investigate various definitions of passing gaps, and these definitions were used to develop passing gap acceptance models. Data on passing maneuvers collected with a driving simulator were used to develop and calibrate three models. The generic structure of these models was composed of the drivers' desire to pass and their gap acceptance decisions. The impact of traffic characteristics, road geometry, and driver characteristics was included in these models. The results show that the passing gap definition has a significant impact on the models' ability to explain passing behavior. Moreover, the estimation results show that modeling a driver's desire to pass the vehicle ahead has a statistically significant contribution in explaining passing behavior. Variables that capture the impact of the traffic conditions, geometric characteristics of the road section, driver characteristics, and the unobserved heterogeneity in the driver population were found to have a significant impact on drivers' desire to pass and their gap acceptance decisions.
|
|
| 33. |
- Varhelyi, Andras, et al.
(författare)
-
Road Infrastructure Safety Management : Review of National Design Guidelines and Procedures
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- As part of the HORIZON EUROPE project AfroSAFE, a review of national regulations, guidelines, and procedures for Road Infrastructure Safety Management (RISM), as well as road design guidelines was carried out in Ghana, Tanzania, and Zambia. Information was collected from relevant authorities and the review had special attention to the safety of vulnerable road users (pedestrians, cyclists, and motorcyclists).
|
|
