Forecast based traffic signal coordination using congestion modelling and real-time data

This dissertation focusses on the implementation of a Real-Time Simulation-Based Signal Coordination module for arterial traffic, as proof of concept for the potential of integrating a new generation of advanced heuristic optimisation tools into Real-Time Traffic Management Systems. The endeavour represents an attempt to address a number of shortcomings observed in most currently marketed on-line signal setting solutions and provide better adaptive signal timings. It is unprecedented in its use of a Genetic Algorithm coupled with Continuous Dynamic Traffic Assignment as solution evaluation method, only made possible by the recently presented parallelisation strategies for the underlying algorithms. Within a fully functional traffic modelling and management framework, the optimiser is developed independently, leaving ample space for future adaptations and extensions, while relying on the best available technology to provide it fast and realistic solution evaluation based on reliable real-time supply and demand data. The optimiser can in fact operate on high quality network models that are well calibrated and always up-to-date with real-world road conditions; rely on robust, multi-source network wide traffic data, rather than being attached to single detectors; manage area coordination using an external simulation engine, rather than a na¨ıve flow propagation model that overlooks crucial traffic dynamics; and even incorporate real-time traffic forecast to account for transient phenomena in the near future to act as a feedback controller. Results clearly confirm the efficacy of the proposed method, by which it is possible to obtain relevant and consistent corridor performance improvements with respect to widely known arterial bandwidth maximisation techniques under a range of different traffic conditions. The computational efforts involved are already manageable for realistic real-world applications, and future extensions of the presented approach to more complex problems seem within reach thanks to the load distribution strategies already envisioned and prepared for in the context of this work

Video vehicle detection at signalised junctions: a simulation-based study

Many existing advanced methods of traffic signal control depend on information about approaching traffic provided by inductive loop detectors at particular points in the road. But analysis of images from CCTV cameras can in principle provide more comprehensive information about traffic approaching and passing through junctions, and cameras may be easier to install and maintain than loop detectors, and some systems based on video detection have already been in use for some time. Against this background, computer simulation has been used to explore the potential of existing and immediately foreseeable capability in automatic on-line image analysis to extract information relevant to signal control from images provided by cameras mounted in acceptable positions at signal-controlled junctions. Some consequences of extracting relevant information in different ways were investigated in the context of an existing detailed simulation model of vehicular traffic moving through junctions under traffic-responsive signal control, and the development of one basic and one advanced algorithm for traffic-responsive control. The work was confined as a first step to operation of one very simple signalcontrolled junction. Two techniques for extraction of information from images were modelled - a more ambitious technique based on distinguishing most of the individual vehicles visible to the camera, and a more modest technique requiring only that the presence of vehicles in any part of the image be distinguished from the background scene. In the latter case, statistical modelling was used to estimate the number of vehicles corresponding to any single area of the image that represents vehicles rather than background. At the simple modelled junction, each technique of extraction enabled each of the algorithms for traffic-responsive control of the signals to achieve average delays per vehicle appreciably lower than those given by System D control, and possibly competitive with those that MOVA would give, but comparison with MOVA was beyond the scope of the initial study. These results of simulation indicate that image analysis of CCTV pictures should be able to provide sufficient information in practice for traffic-responsive control that is competitive with existing techniques. Ways in which the work could be taken further were discussed with practitioners, but have not yet been progressed

To What Extent Does Land Use Catchment Lead to the Design of Junction along EDSA?

The coordination of transport and land use have proven to be difficult in the developing world. Three junctions along EDSA (Epifanio de Los Santos Avenue) were analysed and investigated upon how land use affects the behaviour of traffic on a theoretical basis of trip generation. Each junction was modelled on VISSIM, and this paper uses average speed, queue length and average delay as assessment indicators to conduct the comparison. The relationship between the land use pattern and traffic activity was evident in each case study with regard to the occupancy of land. Thus, stronger implementation of policies and better governance is required to alleviate the issues found and raised from each of the case studies and literature

A Study of Roundabout Sustainability using Traffic Simulation - A Case Study at Ayer Hitam Signalised Intersection

Through urban planning and municipal administration, a sustainable city seeks to solve issues of social, environmental, and economic effect. By integrating environmentally friendly options into local infrastructure, many sustainable efforts are made possible. Vehicle emissions from the road traffic have always been considered one of the most significant sources of global issues due to their harmful effects on the environment and human beings. Additionally, it is currently a concern for sustainability, especially in urban areas. This matter has inspired the researchers to simulate various systems to identify factors and provide solutions for the issue of emission. In this study, VISSIM software was utilised to develop a traffic simulation to estimate emissions level at Ayer Hitam’s signalised intersection in reference to the intersection type as an independent factor. The signalised intersection and a roundabout were chosen to represent controlled and uncontrolled intersections. It aimed to compare the difference in emissions level between the signalised intersection and roundabout. The results of this study show that roundabouts are more effective in enhancing traffic flow than signalised intersections in terms of travel time, delay, queue and have 48.59% lower for (CO), (NOx) and (VOC) emission. An improvement in vehicle emissions results from this study indicates that roundabouts have the potential to contribute to a more sustainable transportation system and sustainable city

Saturation Flow Model at Signalized Intersection for Non-lane Based Traffic

The important parameters in the planning, design and control of a signalized intersection are saturation flows, lost times and passenger car units (PCU). These factors have been traditionally measured, in most western countries, based on the research carried on test tracks and on public roads where traffic is typically car-dominated with vehicles moving in clearly defined lanes. However, the traffic movement in Bangladesh and in other developing countries is rendered in more complex due to the heterogeneous characteristics of the traffic stream using the same right of way. Another striking feature of the road traffic operating condition in developing countries is that, despite having lane markings, most of the times lane discipline is not followed no matter whether non motorized vehicle is present or not. At intersection, there is notable lateral movement and vehicles tend to use lateral gaps to reach the head of the queue. Due to fundamental differences in traffic characteristics, the standard western relationships for predicting the values of saturation flows, lost time, and PCU factors are not appropriate for developing countries. This paper first review principle methods of measurement of saturation flow and selection of proper method to measure this parameter for the traffic condition prevailing in developing countries. The research establishes that unified PCU concept is not true for non-lane based traffic condition. It also proposes PCU and a flow model for estimating capacity of signalized intersection having no lane discipline

PEDESTRIANS CHARATERISTICS AT TRAFFIC LIGHT SIGNAL INTERSECTION IN IPOH

Pedestrian crossing is one of the greatest challenges for the traffic and safety engineering communities. Lack of facilities for pedestrian caused fatal accidents involving pedestrians especially at intersections where there is high volume of vehicles. Many major roads in Malaysia are ignoring the facilities for pedestrian to cross the road. Therefore, many pedestrians risk their live to cross the roads even though they knew the danger and risk they have to take. Concerning pedestrian fatality at intersection, nowadays a lot of facilities for pedestrians have been provided in order to increase the safety of pedestrian at signalized intersection. These include the pedestrian crossing lane, traffic system for pedestrians and provided safe place for pedestrian to cross the road. By adding facilities at traffic light signal, the delays for vehicle will be higher and this can caused heavy congestion. On the other hand, if the delays time for pedestrian is high, the possibility of non-compliance pedestrian will increase. This project studied the characteristic of the pedestrians in term of delays and compliancy at two selected signalized intersections. Traffic survey was conducted to study the performance of the traffic signal with the existence of pedestrian facilities at the two intersections selected. Two types of traffic signal for pedestrians were used namely pushbutton system which located at Jalan Sultan Yusuf and fixed-time system which located at Jalan Dato Onn Jaafar- Jalan Sultan Idris Shah. The performance of the road as well as performance of pedestrian crossing was analyzed using SIDRA software. Finally, recommendations on how to improve the intersection were proposed. The average walking speed for pedestrian is 1. 6 m/s for free-flow walking. The average walking speed is 1.28 m/s and 1.56 m/s for both traffic systems. It can be concluded that the average walking speed at the intersections is quite normal. Non-compliance pedestrians at the intersection are quite low at both sites. For Jalan Sultan Yusuf, the LOS for pedestrian is B while for vehicle is D. For Jalan Dato Onn Jaafar- Jalan Sultan Yusuf the LOS for pedestrian and vehicle is B and D, respectively

Heterogenous motorised traffic flow modelling using cellular automata

Traffic congestion is a major problem in most major cities around the world with few signs that this is diminishing, despite management efforts. In planning traffic management and control strategies at urban and inter urban level, understanding the factors involved in vehicular progression is vital. Most work to date has, however, been restricted to single vehicle-type traffic. Study of heterogeneous traffic movements for urban single and multi-lane roads has been limited, even for developed countries and motorised traffic mix, (with a broader spectrum of vehicle type applicable for cities in the developing world). The aim of the research, presented in this thesis, was thus to propose and develop a model for heterogeneous motorised traffic, applicable to situations, involving common urban and interurban road features in the western or developed world. A further aim of the work was to provide a basis for comparison with current models for homogeneous vehicle type. A two-component cellular automata (2-CA) methodology is used to examine traffic patterns for single-lane, multi-lane controlled and uncontrolled intersections and roundabouts. In this heterogeneous model (binary mix), space mapping rules are used for each vehicle type, namely long (double-unit length) and short (single-unit length) vehicles. Vehicle type is randomly categorised as long (LV) or short (SV) with different fractions considered. Update rules are defined based on given and neighbouring cell states at each time step, on manoeuvre complexity and on acceptable space criteria for different vehicle types. Inclusion of heterogeneous traffic units increases the algorithm complexity as different criteria apply to different cellular elements, but mixed traffic is clearly more reflective of the real-world situation. The impact of vehicle mix on the overall performance of an intersection and roundabout (one-lane one-way, one-lane two-way and two-lane two-way) has been examined. The model for mixed traffic was also compared to similar models for homogeneous vehicle type, with throughput, queue length and other metrics explored. The relationship between arrival rates on the entrance roads and throughput for mixed traffic was studied and it was found that, as for the homogeneous case, critical arrival rates can be identified for various traffic conditions. Investigation of performance metrics for heterogeneous traffic (short and long vehicles), can be shown to reproduce main aspects of real-world configuration performance. This has been validated, using local Dublin traffic data. The 2-CA model can be shown to simulate successfully both homogeneous and heterogeneous traffic over a range of parameter values for arrival, turning rates, different urban configurations and a distribution of vehicle types. The developed model has potential to extend its use to linked transport network elements and can also incorporate further motorised and non-motorised vehicle diversity for various road configurations. It is anticipated that detailed studies, such as those presented here, can support efforts on traffic management and aid in the design of optimisation strategies for traffic flow

Review and ranking of crash risk factors related to the road infrastructure

The objective of this paper is the review and comparative assessment of infrastructure related crash risk factors, with the explicit purpose of ranking them based on how detrimental they are towards road safety (i.e. crash risk, frequency and severity). This analysis was carried out within the SafetyCube project, which aimed to identify and quantify the effects of risk factors and measures related to behaviour, infrastructure or vehicles, and integrate the results in an innovative road safety Decision Support System (DSS). The evaluation was conducted by examining studies from the existing literature. These were selected and analysed using a specifically designed common methodology. Infrastructure risk factors were structured in a hierarchical taxonomy of 10 areas with several risk factors in each area (59 specific risk factors in total), examples include: alignment features (e.g. horizontal-vertical alignment deficiencies), cross-section characteristics (e.g. superelevation, lanes, median and shoulder deficiencies), road surface deficiencies, workzones, junction deficiencies (interchange and at-grade) etc. Consultation with infrastructure stakeholders (international organisations, road authorities, etc.) took place in dedicated workshops to identify user needs for the DSS, as well as “hot topics” of particular importance. The following analysis methodology was applied to each infrastructure risk factor: (i) A search for relevant international literature, (ii) Selection of studies on the basis of rigorous criteria, (iii) Analysis of studies in terms of design, methods and limitations, (iv) Synthesis of findings - and meta-analysis, when feasible. In total 243 recent and high quality studies were selected and analysed. Synthesis of results was made through 39 ‘Synopses’ (including 4 original meta-analyses) on individual risk factors or groups of risk factors. This allowed the ranking of infrastructure risk factors into three groups: risky (11 risk factors), probably risky (18 risk factors), and unclear (7 risk factors)

Straight lane saturation flow and its rate in serbian cities

Saturation flow is the base rate in the procedure for optimizing traffic signal operation and determining the measure for effectiveness of intersection operation. Different approaches and structures of analytical value models indicate the complexity of the problem of determining the saturation flow value in real conditions. This paper presents the synthesis of the results and conclusions of studying the saturation flow rate phenomenon at signalised intersections in Serbia in the last thirty years, by applying various survey techniques. The surveys relate to straight lane saturation flow value, in the survey conditions mostly resembling the idealised conditions in which saturation flow can be generated. The obtained results indicate that there is a significant trend of changes in the base saturation flow value compared with those first referred in 1963 by Webster and Cobbe, change in the significance of impact factor on saturation flow value, and the necessity to determine them on the local level