Portland State University. Department of Civil and Environmental Engineering
Date of Award
Master of Science (M.S.) in Civil & Environmental Engineering
Civil and Environmental Engineering
Traffic circles -- United States -- Design and construction, Roads -- United States -- Interchanges and intersections -- Design and construction, Cycling -- Safety measures
The focus of this project is to see how a turbo roundabout and a protected intersection designs behave when they are applied on two study sites in Portland, OR. PTV VISSM is used to model, analyze and compare the performances of these designs with the existing intersection. In addition, the best features of the protected intersection and the turbo roundabout were combined to create a new intersection design that is safer for the bicyclists and also performs better than the existing intersection.
The analysis is conducted for five different volume scenarios for both the study sites. The results of the analysis show that both the proposed designs perform better than the existing intersection at both study sites. In addition, study site-II, which is the intersection of SE 92nd Ave & SE Flavel St, was examined for the combination of a protected intersection with a turbo roundabout at the intersection. Both the safety features and the performance of the intersection were improved significantly with the treatment.
The results in this project shows promise at reducing traffic crashes and increasing performance at intersections. At NW 23 Ave & NW Vaughn St Intersection, the existing signalized intersection was transformed into a turbo roundabout, this resulted in the average delay being reduced by 85.43%, the average speed increased by 52.5%, and the total travel time being reduced by 31.68%. At SE 92nd Ave & SE Flavel St, the existing signalized intersection was transformed into a protected intersection design, which resulted in the average delay being reduced by 10.11%, the average speed increased by 3.09%, and the total travel time being increased by 10.05%. Again on SE 92nd Ave & SE Flavel St Intersection, the existing design was transformed into a turbo roundabout, which is incorporated with a protected intersection: the average delay was reduced by 32.69%; the average speed increased by 24.72%; and the total travel time was reduced by 26.02%. However, these are just simulation results assuming all road users will follow the road rules, which in the real world is not always true. Therefore, further studies using different simulation software, performance parameters and even by implementing them on different representative sites should be done in the future.
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Woldetinsae, Aman K., "A Microsimulation of Novel Intersection Designs" (2015). Civil and Environmental Engineering Master's Project Reports. 14.