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

Safety and Operational Impacts of Alternative Intersections

As the degradation of service at some conventional intersections increases, there becomes a need for alternative solutions other than expensive interchanges. Many alternative intersections have been proposed in the past. Under certain traffic and local conditions some solutions are more promising than other. In some cases, the conventional intersection may still be the optimal choice. The presented research focused on developing guidelines that would help planners and designers identify the most promising solutions for further analysis. This objective has been addresses in two ways. Firstly, the existing knowledge on alternative intersections has been identified. Secondly, the performance of conventional and alternative intersections under a range of Indiana traffic conditions has been evaluated using micro-simulation model - VISSIM. Although a large number of sources could be found on the research subject, the existing knowledge about performance of alternative intersection design is incomplete. Only a few designs proposed in the past have been applied at a considerable number of locations including roundabouts, median U-turns, and jag-handle intersections. Other types still await implementation. The available sources are not comprehensive and deal with conditions that might be different from Indiana. The knowledge of the safety impact of these intersections is very limited. A large number of more than 1,300 scenarios were simulated runs performed with VISSIM calibrated to Indiana conditions. The simulated types of intersections included: conventional, roundabouts, jag-handle near-sided and far-sided, median U-turns, and continuous-flow intersection. Except roundabouts, all other intersections were signalized to test their capacity limits and delay-based performance. Although the roundabouts were the lowest delays at low volumes they also reached the capacity before other did. The most promising solutions for heavy volumes are median U-turns and continuous-flow intersections. The presented research developed guidelines for using alternative intersection designs. The guidelines compile the existing knowledge found in existing publications and research reports with the simulation experiments performed with VISSIM. The guidelines are ready to use and will help planners and designers determine which intersection types are the most promising under considered conditions and should be considered in a detailed way. The simulation results have been summarized in an easy to use format of graphs

Upgrading of Milner and Klipfontein Road Southbound Approach to alleviate traffic issues

Introduction The population of the world is increasing at a rate of 1.07% each year. In order to accommodate this growth, quality and efficiency of services need to be improved. This includes improving the quality and efficiency of the transportation services, as a country's sustainability is reliant upon these systems. In many countries, the increase in population has congested the CBD areas, forcing people to migrate outside of the CBD. This has resulted in urban sprawl. However, the apartheid era has resulted in urban sprawl in South Africa, which left many people living along the periphery, close to the industrial areas and a distance away from the CBD. One of the biggest challenges people living outside of the CBD area experience, is a poor and unreliable public transport system. It is difficult for people to access other areas and this has increased the number of private vehicles on the road. According to a list of the top 10 countries with the highest public transport ridership, that was developed by Worldatlas.com (2019), Kenya has the highest public transport ridership. Of the total population, 63% of the people use public transport. Furthermore, the other 9 countries mentioned have ridership volumes ranging from 53% to 57%. This proves that 40% to 50% of the population in other countries is still using private vehicles above public transport and this is still considered high. Research Problem The use of private vehicles in South Africa has been on the rise. As a result, the congestion levels on the roads have increased. This has resulted in longer travel times, busier roads and an increase in road accidents as drivers spend more time travelling to and from destinations. Milner and Klipfontein Road is located in Mowbray. The intersection is surrounded by a shopping mall, a hospital, a clinic, a school and a number of other amenities. Therefore, the traffic travelling through this intersection daily is relatively high. The southbound approach of Milner and Klipfontein Road intersection, however, has the highest volume of traffic operating through the intersection daily, as it connects the M5 highway (Class 2) and Raapenberg Road (Class 3) to Klipfontein Road (Class 3). The southbound approach is a three-lane approach, of which one lane is a short turning lane. With high volumes of traffic operating through this approach daily, the road tends to get very congested, especially during the peak period. The high congestion levels have resulted in a number of other issues, which include longer travel times from Alexandra and Raapenberg Road intersection to Milner and Klipfontein Road intersection, vehicles struggling to change lanes due to limited gap length available and spilling of traffic onto Raapenberg Road. This study will, therefore, focus on finding suitable measures to assist with alleviating the congestion as well the other issues currently being experienced along the southbound approach of Milner and Klipfontein Road. Literature Review It is important to manage the transport system as this affects the economy of the country. There are two types of traffic congestion and they are either recurrent or non-recurrent. Traffic congestion is a result of having too many vehicles on the road i.e. when the demand is larger than the supply. It is, therefore, necessary to improve the quality of a road or an intersection. There are three types of intersection designs and they include: priority control, traffic signals and rotary movement control. It is important to determine the most efficient way for an intersection to operate by determining the way in which conflicting volumes will be served. To avoid undesirable delays and deal with large volumes of traffic, signalised or rotary movement is often preferred. At signalised intersections, it is important to measure the effectiveness of an intersection by evaluating its performance and the design of the signal process as this can affect the time of travel, choice of route, mode of transport and If the route will be completed. To measure the effectiveness of the signalised intersection, the following elements must be assessed: the capacity, the volume to capacity ratio, the delay and the queue length. The Level of Service (LOS) also plays an important role in determining the operation of the intersection and provides the engineer or designer with information related to the type of flow or movement at each approach and intersection. The signal design plays an important role in the operation of the intersection too. It is important to ensure that the signal timing is correct as this can affect the flow of traffic. There are different signal controls that can be implemented, and they include, semi actuated, fully actuated and fixed timing. To retime a signalised intersection is considered the most cost-effective method of redesign. Phasing of the intersection is important as this can affect the level of service of operation of the intersection. To determine which phasing is necessary, the following must be assessed: the number of road accidents, the sight distance available, the geometry of the road, speeds of vehicles, the total volumes and the operation of the intersection. Unsignalised intersections are generally not preferred as volumes and speeds differ at each approach. High accident statistics are expected. This affects the overall capacity and operation of an intersection. Rotary movement control which refers to roundabouts or traffic circles, can handle larger volumes of traffic and reduce conflicting movements. They are therefore, considered much safer than other forms of at-grade intersections. The literature review will provide more detail regarding traffic congestion, intersection design and measuring the effectiveness of an intersection. Data collection and Analysis The site investigation was undertaken on 20 February 2019 between the AM peak (6:00 and 8:30) and the PM peak (16:00 and 18:30), to determine the extent of the traffic congestion currently being experienced, along the southbound approach of Milner and Klipfontein Road. Based on the findings, the PM peak period was considered the “worst case scenario”. A traffic count was not required; as previous traffic count data was available from the City of Cape Town records. A full traffic count was completed in 2017 for the entire intersection. A travel time survey was undertaken on Wednesday, 24 July 2019 between 16:00 and 18:00. The runs were calculated at 10-minute intervals. The data obtained from this survey was validated against the traffic count survey to determine whether the data obtained from City of Cape Town records, was indeed correct. It should be noted that the travel time survey was only completed during the PM peak, as the majority of traffic travel along that approach (direction towards home), during the PM peak. It was also confirmed to be the time of day when traffic was the worst. During the process of the travel time survey, a separate survey was completed to determine the direction in which vehicles were travelling. The vehicles were monitored from where they entered the southbound approach (M5 highway or Raapenberg Road), whether they stayed in the lane they entered the approach or whether they changed lanes. This survey would determine the destination of travel. Furthermore, vehicles changing lanes, were also further monitored, to determine if they were undertaking this movement legally or illegally. A solid white line, located approximately 200m away from the signalized Milner and Klipfontein intersection, separates the two lanes entering from M5 highway and Raapenberg Road. It prevents vehicles from changing lanes when unsafe to do so. The data was captured in Sidra and Junction to assess the delay and level of service at the intersection and specifically along the southbound approach of Milner and Klipfontein Road intersection. Results and findings The southbound approach is a three-lane approach. It comprises of a left lane, which is used for straight ahead movements and left turning movements, a middle lane used for straight ahead movements and a short right turn lane. The traffic count data that was obtained from the City of Cape Town records for 2017, established that a high volume of traffic passed through Milner and Klipfontein Road intersection daily. The peak periods of the day had a variation in the volumes of traffic along each approach, except for the southbound approach, which had high volumes of traffic at both peak periods. Majority of the traffic enters from either M5 highway or Raapenberg Road and exits onto Milner or Klipfontein Road eastbound. The signal phasing at the intersection comprises 4 phases, with no priority given to the southbound approach eastbound movements, even though the highest traffic volumes travelling in that direction. This has resulted in traffic congestion and a backlog of traffic onto Raapenberg Road. As a result, vehicles take longer than necessary to reach the intersection. The travel time survey investigated vehicles travelling from Alexandra and Raapenberg Road towards Milner and Klipfontein Road. The total distance is 1.2km in length. On average, a driver driving at a speed of 60km/hr. (length of road is short, and it bends), should take 3 minutes and 20 seconds to complete this stretch of road. This total time is inclusive of the signal system. It took vehicles more than 7 minutes to complete the 1.2km distance. The road accident statistics also indicate that a high number of accidents take place at Milner and Klipfontein Road intersection. Over the latest five-year period, a total of 256 accidents took place at the intersection. Of the 256 accidents, 53% of the accidents took place along the southbound approach. Furthermore, the directional survey also established that majority of the vehicles entering from both Raapenberg and the M5 highway, were travelling eastbound along Klipfontein Road. Majority of the vehicles changing lanes, have however, done this legally (not crossing the solid line). As a result, many vehicles were merged between two lanes, obstructing oncoming vehicles. It is evident from the results that there is a need for mitigating measures. High volumes of traffic are experienced along the southbound approach, with a high portion of this traffic wanting to make use of the left lane. Limited gaps are available for changing lanes, travel time is longer than expected and spilling of traffic is occurring on Raapenberg Road all due to high congestion levels along the southbound approach. It is therefore proposed that a roundabout be constructed at Milner and Klipfontein Road intersection to reduce conflicting movements, improve the delay and LOS of the intersection and reduce the issues currently being experienced along the southbound approach. Recommendations It is recommended that a proper design be completed to understand the proper effects in terms of operation of the intersection by implementation of a roundabout. Further research should be undertaken to determine the effect of the roundabout on the AM peak

Redesign of Newton Square

This project focused on improving the efficiency of Newton Square, a five street roundabout located in Worcester, Massachusetts; the team collaborated with the Massachusetts Department of Transportation and other public agencies and committees. A turning movement count was completed at this intersection to determine the level of service, as well as simulations of how design alternatives would alleviate congestion were conducted. After analyzing the data collected, the optimal design alternative was determined to enhance the accessibility for motorists, bicyclists and pedestrians

The Application of Traffic Calming and Related Strategies in an Urban Environment

This thesis presents a collection of network optimization strategies aimed at aiding the local practitioner in selecting, implementing, and evaluating appropriate strategies to achieve community goals and objectives in the urban environment. The urban environment is often challenging due to the plethora of activity and variety in mode choice. Growing interest in sustainable transportation practices along with encouragement at the Federal, State, and Local levels to is leading to the growing use of non-motorized modes of transportation such as walking and bicycling. The combination of high population density and mixed land use in the urban environment creates unique safety and operational challenges. This research presents a synthesis of strategies designed to improve local transportation safety and efficiency by targeting speeding and cut-through volumes as improving pedestrian and bicycle facilities in urban areas such as those found in Western Massachusetts. Additionally, this research evaluates two local network optimization strategies; speed cushions and reverse angle parking. The effectiveness of the speed cushions in achieving the community’s goal of reducing speeds was evaluated and determined to be a recommended strategy for future implementation, especially when couple with enforcement. Reverse angle parking, however, was not determined to be an effective strategy due to the high occurrence of events as well as lower parking volume exhibited during implementation

How We Can Have Safe, Clean, Convenient, Affordable, Pleasant Transportation Without Making People Drive Less or Give Up Suburban Living

In this report, the authors propose a dual-transportation network and community that would accommodate the preferences for auto-mobility and single-family homes,yet also offer much safer and cleaner, more pleasant and more socially integrated environment than what is commonly proposed in transportation and land use plans. A city with two universally accessible but completely separate and independent transportation networks is proposed. One network is for low-speed lightweight modes (LLMs) and the other is for fast-moving heavy vehicles (FHSVs). The authors review the economics and advantages of such a design, as well as the impacts on transportation problems. They conclude with a discussion regarding the social,political, and consumer factors determining the success of the proposed design

Deriving and validating performance indicators for safety mobility for older road users in urban areas

This thesis derives and validates Performance Indicators for Safe Mobility for Older Road Users in Urban Areas. Performance Indicators are objective, auditable parameters, which when used as a set can provide additional information to decision-makers about the operation of the transport system. Great Britain, in common with many countries across Europe has an ageing population. The proportion of older people who hold a driving licence and have the use of a car is also expected to rise, with future generations of older people travelling further and more frequently than previous generations. Older road users are already over-represented in traffic fatalities, particularly in urban areas. Measures to protect older road users from risk in traffic will be of crucial importance as the population ages. However, against this background the need remains for them to access key facilities such as shops, leisure activities and health care. Maintaining independent mobility is essential in maintaining mental and physical health. Traditionally, outcomes-based measures such as accident or casualty figures have been used to monitor road safety. Techniques such as hotspot analysis have identified locations on the road network where accident numbers are high, allowing modifications to road infrastructure to be designed and implemented. Using outcomes measures alone however, it is difficult to ascribe improvements in accident or casualty figures to particular policy interventions. Moreover, the effect of road safety interventions on other related policy areas mobility being one is impossible to assess without access to detailed, disaggregated exposure data. To make fully informed policy decisions about infrastructure design and how it affects older users, a better understanding of the linkages between safety and mobility is required. Performance Indicators offer the possibility to look at these linked policy objectives within a single framework. Focus group data was used in conjunction with the results of previous studies to identify the infrastructure features which present a barrier to older users safe mobility in urban areas. These included factors which increased risk, such as wide carriageways, complex junctions and fast-moving traffic, and factors which hindered mobility, such as uneven or poorly maintained pavements, poor lighting and traffic intrusion. A thematic audit of infrastructure in a case study city (Coventry) was undertaken, in order that the incidence of such infrastructure could be recorded. It was found that in many areas of the city, safe mobility for older road users was not well provided for, with the majority of locations having barriers to safety and/or mobility for both drivers and pedestrians. The audit data was then used to calculate a set of Performance Indicators, presented via spider graphs, which describe the degree to which the infrastructure caters for the safety and mobility of older drivers and pedestrians. The spider graphs allow for easy comparisons between the different geographical areas, and also between the different policy areas, allowing policy priorities to be identified. The calculated Performance Indicators were validated using case studies collected from the focus group participants. The case studies identified features that affected travel habits by causing a change of route or change of mode, providing evidence of the link between infrastructure design and safe mobility for older users. The results of the Performance Indicator analysis were then compared to accident figures, in order to identify differences between the two approaches, and to understand what policy implications would result from a monitoring framework that used Performance Indicators for safe mobility, rather than outcomes-based measures alone. One implication of the Performance Indicator approach is that it may identify different areas for priority action from those identified by accident or casualty figures. A location which does not have high accident numbers may nevertheless perform poorly on a Safety Performance Indicator measure. This is because older users who feel at risk make different route or mode choices to avoid the infrastructure, the lower accident rate being explained by lower exposure to risk. Conversely, measures to promote independent mobility for older users may increase their accident involvement, not because the environment becomes more risky, but because the exposure of older users to risk increases, because they are willing and able to walk or drive in an area they previously avoided. The thesis concludes that infrastructure design does not currently cater well for the needs of older pedestrians and drivers, and that a framework which incorporated Performance Indicators could make more explicit the trade-offs between safety and mobility, and between different categories of user. This additional information would enable policy makers and practitioners to make more informed decisions about how to prioritise competing objectives in complex urban areas