Traditional crash frequency prediction models cannot capture the temporal effects of traffic characteristics due to the high level of data aggregation. Also, this approach is less suitable to address the crash risk for active traffic management strategies that typically operate for short-time intervals. Hence, this research proposes short-term crash prediction models for traffic management strategies such as Variable Speed Limit (VSL)/Variable Advisory Speed (VAS), and Part-time Shoulder Use (PTSU). By using high-resolution traffic detectors and VSL/VAS operational data, short-term Safety Performance Functions (SPFs) are estimated at weekday hourly and peak period aggregation levels. The results indicate that the short-term SPFs could capture various crash contributing factors and safety aspects of VSL/VAS more effectively than the traditional highly aggregated Average Annual Daily Traffic (AADT)-based approach. The study also investigates the safety effectiveness of VSL/VAS for different types and severity levels of traffic crashes. The results specify that the VSL/VAS system is effective in reducing rear-end crashes in the Multivariate Poisson Lognormal (MVPLN) crash type model as well as Property Damage Only (PDO) and C (non-incapacitating) crashes in the MVPLN crash severity model. Recommendations include deploying the VSL/VAS system combined with other traffic management strategies, strong enforcement policies, and drivers' compliance to increase the effectiveness of this strategy. Further, this research estimates the Random Parameters Negative Binomial-Lindley (RPNB-L) model for PTSU sections and provides valuable insights on potential crash contributing factors related to PTSU operation, design elements, and high-risk areas. Last, the study proposes a novel integrated crash prediction approach for freeway sections with combined traffic management strategies. By incorporating historical safety conditions from SPFs, real-time crash prediction performance could be improved as a part of proactive traffic management systems. The findings could assist transportation agencies, policymakers, and practitioners in taking appropriate countermeasures for preventing and reducing crash occurrence by incorporating safety aspects while implementing traffic management strategies on freeways.

Die Dissertation befasst sich mit der Erweiterung und Anwendung des allgemeinen räumlichen Gleichgewicht- und Transportmodells RELU-TRAN (Anas und Liu, 2007) und analysiert verschiedene verkehrs- und klimabezogene Politikmaßnahmen (Tempo-30 in Städten, Infrastrukturqualität, Anpassung an den Klimawandel) in einer Stadtökonomie.

This thesis consists of five scientific articles oriented towards capacity. Managing capacity constraints with associated delays is a big issue at new design as well as at trimming existing traffic facilities. In larger Swedish cities these challenges have become more and more important as a result of growing traffic demand due to rapid population increase.Models for estimating capacity and delay are available, but not many are calibrated for Swedish conditions due to the high effort required. This thesis documents development and calibration of new models for motorway links, entry and exit lanes and weaving areas and an developed space-time model with the ability to calculate queue length, delay, etc.The first article is focused on identifying weaknesses in the former Swedish capacity method for motorways, and development of new models overcoming these shortcomings. The development includes new models for jam density at queue, capacity in weaving areas and fundamental flow-density relationships for 15 different highway types for inclusion in the new Swedish capacity manual.The second article describes the development of a Swedish motorway space-time model to estimate travel times and queues in oversaturated conditions based on the American FREEVAL model in Highway Capacity Manual 2010 (HCM 2010). Calibration and validation of the model has been performed with data from the Motorway Control System (MCS) in Stockholm. A good correspondence was obtained for most cases, but further calibration and validation efforts are required for entry and exit lanes.The third article describes further development of the intersection model in the Swedish microscopic model “Rural Traffic Simulator (RuTSim). This is a continuation of the work documented in the author’s licentiate thesis published in 2002. The development focused on simulation of intersections using a new concept on lane use not included in the old RuTSim model. The model describes Swedish rural intersections with flared approaches providing a non-discreet lane use due to vehicle types in queue. New data for calibration and validation data was also generated. The validation results showed good correspondence between simulated and empirical delay results. The new intersection model is now implemented in RuTSim, providing new tools for estimation of capacity, delay and queue length already included in Swedish guidelines and capacity manuals/software (Capcal).The fourth article describes the development of a new capacity model for roadwork zones. Focus is on the resulting capacity of one lane due to several reduction factors. These factors include impacts of closed road shoulders, reduction of number of lanes, diversion of traffic to the opposite carriageway, commuting traffic, length of work zone, lane width and type of road work. The first two correction factors were successfully validated in a full-scale test on the E6 motorway in Gothenburg.The fifth article describes development and implementation of a new harmonization algorithm for MCS systems on motorways designed to increase bottleneck capacity and throughput. Two different models were developed, one of which was implemented in the existing MCS system on E4 Södertäljevägen south of Stockholm. Full-scale trials were carried out with a model based on trigger levels in terms of flow. The second model based on the difference in the variance of speed during two following time periods was tested offline also with very good results. / <p>QC 20160429</p>

<p>The Road Administration wants to improve safety at a hazardous, rural road intersection near Åkersberga, Stockholm by changing the design of the intersection. The intersection today is a three-way connection with a small road connecting to a four-lane main road, much similar to a motorway with high speeds although with a speed limit of 90km/h. Drivers’ attention and velocity in different designs of the intersection are analysed in this thesis with data from two experiments, ordered by the Road Administration and conducted by the Swedish National Road and Research Institute (VTI). Four alternative designs of the intersection were tested using the VTI-simulator; a narrowing from two to one lane through the intersection, rumble strips, a wooden fence and trees at the road side, and a portal framing the intersection. In addition, the original intersection design, both with and without speed limit signs of 70km/h, were tested for comparisons. In the first of the two experiments, the four alternative intersection designs all had speed limit signs of 70km/h, and in the second experiment the alternative intersection designs were tested without the influence of the speed limit signs of 70km/h. Data used in the analyses are velocity data, lateral position, eye movements, brake data and subjective estimations.</p><p>Subjects were found to look at the critical areas of the intersection in time, independent of intersection design. Only small differences between the intersection designs were found, probably due to width of the main road being a larger design-influence than the measures tested. The results are in favour of the narrowing from two to one lane through the intersection, but traffic density and rhythm make a narrowing difficult to realise at the real intersection. Instead, rumble strips in addition to a speed limit of 70km/h can be recommended, although rumble strips are most likely to increase inattentive drivers’ readiness.</p>

The Road Administration wants to improve safety at a hazardous, rural road intersection near Åkersberga, Stockholm by changing the design of the intersection. The intersection today is a three-way connection with a small road connecting to a four-lane main road, much similar to a motorway with high speeds although with a speed limit of 90km/h. Drivers’ attention and velocity in different designs of the intersection are analysed in this thesis with data from two experiments, ordered by the Road Administration and conducted by the Swedish National Road and Research Institute (VTI). Four alternative designs of the intersection were tested using the VTI-simulator; a narrowing from two to one lane through the intersection, rumble strips, a wooden fence and trees at the road side, and a portal framing the intersection. In addition, the original intersection design, both with and without speed limit signs of 70km/h, were tested for comparisons. In the first of the two experiments, the four alternative intersection designs all had speed limit signs of 70km/h, and in the second experiment the alternative intersection designs were tested without the influence of the speed limit signs of 70km/h. Data used in the analyses are velocity data, lateral position, eye movements, brake data and subjective estimations. Subjects were found to look at the critical areas of the intersection in time, independent of intersection design. Only small differences between the intersection designs were found, probably due to width of the main road being a larger design-influence than the measures tested. The results are in favour of the narrowing from two to one lane through the intersection, but traffic density and rhythm make a narrowing difficult to realise at the real intersection. Instead, rumble strips in addition to a speed limit of 70km/h can be recommended, although rumble strips are most likely to increase inattentive drivers’ readiness.

Variable Speed Limit (VSL) strategies identify and disseminate dynamic speed limits that are determined to be appropriate based on prevailing traffic conditions, road surface conditions, and weather conditions. This dissertation develops and evaluates a shockwave-based VSL system that uses a heuristic switching logic-based controller with specified thresholds of prevailing traffic flow conditions. The system aims to improve operations and mobility at critical bottlenecks. Before traffic breakdown occurrence, the proposed VSL’s goal is to prevent or postpone breakdown by decreasing the inflow and achieving uniform distribution in speed and flow. After breakdown occurrence, the VSL system aims to dampen traffic congestion by reducing the inflow traffic to the congested area and increasing the bottleneck capacity by deactivating the VSL at the head of the congested area. The shockwave-based VSL system pushes the VSL location upstream as the congested area propagates upstream. In addition to testing the system using infrastructure detector-based data, this dissertation investigates the use of Connected Vehicle trajectory data as input to the shockwave-based VSL system performance. Since the field Connected Vehicle data are not available, as part of this research, Vehicle-to-Infrastructure communication is modeled in the microscopic simulation to obtain individual vehicle trajectories. In this system, wavelet transform is used to analyze aggregated individual vehicles’ speed data to determine the locations of congestion. The currently recommended calibration procedures of simulation models are generally based on the capacity, volume and system-performance values and do not specifically examine traffic breakdown characteristics. However, since the proposed VSL strategies are countermeasures to the impacts of breakdown conditions, considering breakdown characteristics in the calibration procedure is important to have a reliable assessment. Several enhancements were proposed in this study to account for the breakdown characteristics at bottleneck locations in the calibration process. In this dissertation, performance of shockwave-based VSL is compared to VSL systems with different fixed VSL message sign locations utilizing the calibrated microscopic model. The results show that shockwave-based VSL outperforms fixed-location VSL systems, and it can considerably decrease the maximum back of queue and duration of breakdown while increasing the average speed during breakdown.

This master‘s thesis describes the design and implementation of the system for detection and recognition of speed limit road signs. It focuses on the recognition of the red circular speed limit sign from the image data using the computer vision methods. Several methods were programmed and tested as a part of this thesis. In the final solution, the segmentation based on YCbCr color model is used. Detection of the circular sign and final classification is performed by template matching method. Algorithm for the tracking of the detected signs between frames of the video is used for better performance in real-time recognition. Application is developed using MATLAB and Simulink. The result is a simple driver assistance system prototype, which can be implemented in any computer with camera. The correct function of the algorithm was confirmed during a testing in a traffic.

The thesis with the title “Designing and simulating a Car2X communication system using the example of an intelligent traffic sign” has been done in Chemnitz University of Technology in the faculty of Computer Science. The purpose of this thesis is to define a layered architecture for Infrastructure to Vehicle (I2V) communication and the implementation of a sample intelligent traffic sign (variable speed limit) application for a Car2X communication system. The layered architecture of this thesis is defined based on three related projects. The application is implemented using the defined layered architecture. Considering the availability of hardware, the implementation is done using the network simulator OMNET++. To check the feasibility of the application three scenarios are created and integrated with the application. The evaluation is done based on the result log files of the simulation which show that the achieved results conform with the expected results, except some minor limitations.

The thesis with the title “Designing and simulating a Car2X communication system using the example of an intelligent traffic sign” has been done in Chemnitz University of Technology in the faculty of Computer Science. The purpose of this thesis is to define a layered architecture for Infrastructure to Vehicle (I2V) communication and the implementation of a sample intelligent traffic sign (variable speed limit) application for a Car2X communication system. The layered architecture of this thesis is defined based on three related projects. The application is implemented using the defined layered architecture. Considering the availability of hardware, the implementation is done using the network simulator OMNET++. To check the feasibility of the application three scenarios are created and integrated with the application. The evaluation is done based on the result log files of the simulation which show that the achieved results conform with the expected results, except some minor limitations.

This diploma thesis deals with the possibilities of determining the influence of electronic stability systems on the chassis of the vehicle driving dynamics. In the introductory section is made theoretical analysis of road vehicle dynamics. Further description is made of some stabilization systems and situations and how to solve them by using these systems. Chapter 6.2.1 describes the methodology of practical experiment, which can determine influence of the stability system of the vehicle chassis on driving dynamics. The next chapter describes an experiment conducted and interpreted the measured values. The penultimate chapter is a simulation of this experiment using simulation software Virtual Crash. The last chapter is an evaluation of the experiment and compares the results with simulation programs using the same input conditions. The conclusion summarizes the results of this work.