Abstract

BSTRACT: Traffic delay is one of the most important factors used in intersection analysis. This study focused on the average delay by looking at different alternative junction models. These different models analyzed with and without signalization according to cycle length in order to help create alternate designs. Green intervals were optimized to reduce average delay in order to assist the level of service for the given junction. The traffic and geometric data were taken from the Imam Hamza Intersection as a case study. A delay problem in this intersection of Dohuk city (northern Iraq) was analyzed and redesigned under the present conditions of right-of-way and volumes of traffic. Firstly redesign for signalized intersection was done by expanding the roads of each approach. Then designs of three new interchange models were proposed. A forecasting of traffic volumes for the next fifteen years was taken using each design model. The simulations for these new models were taken by applying different scenarios for each model in order to find the best results of delay and level of service. Likewise a comparison was made based on the best amount of delay obtained from these new models. Finally, the level of delay for the peak hours of each model was compared with the current level of delay in the intersection in order to find the total delay hours for next fifteen years and determine the most effective design in terms of reducing delay in the given intersection. The conclusion of this study displayed the second model diamond interchange had the minimum results of delay comparing with the other models. Keywords: Delay, Signalized intersection, Diamond interchange, Imam Hamza Intersection, Level of service, Traffic jam, Delay time cost. ………………………………………………………………………………………………………………………… ÖZ: Kavşak analizinde en önemli etkenlerden biri de trafikte yaşanan gecikmelerdir. Bu araştırma alternatif kavşak modellerini ele alarak ortalama bekleme sürelerinin sonuçlarını mercek altına almayı hedeflemektedir. Bu farklı modeller alternatif tasarımlar yaratmak için sinyal süresine göre hem sinyalizasyon ile hem de sinyalizasyonsuz halde analiz edilecektir. Söz konusu olan kavşağın hizmet seviyesini artırmak için yeşil ışığın süreleri en iyi şekilde kullanılarak ortalama bekleme gecikme süresinin azaltılması amaçlanmaktadır. Trafik ve geometrik veriler örnek olay incelemesi olarak Imam Hamza kavşağından alınacaktır. Irak’ın kuzeyindeki Dohuk şehrinde bulunan bu kavşaktaki bir gecikme problemi mevcut trafiğin sağ şeridi ve trafik yoğunluğunun durumu göz önünde bulundurularak analiz edilip yeniden tasarlanacaktır. Elmas şeklinde köprülü kavşağın üç yeni modelini tasarlamak için önümüzdeki 15 yılın trafik yoğunluk tahminleri dikkate alınacaktır. Aynı şekilde söz konusu olan yeni modeller ile benzer yollardaki gecikme süresi baz alınarak bir karşılaştırma da yapılacaktır. Bu süre miktarı tespit edilince gecikmeden dolayı oluşan maliyet belirlenebilecektir. Son olarak, gelecek 15 yılın toplam gecikme süresini bulmak, en etkili modeli belirlemek ve verilen kavşaktaki gecikme süresini düşürmek için her modelin yoğun saatlerdeki gecikme süresi ve kavşaktaki şimdiki gecikme süresi karşılaştırıldı. Anahtar Sözcükler: Gecikme, siyalizasyonlu kavşak, Elmas şeklinde kavşak, Imam Hamza kavşağı, Hizmet seviyesi, Trafik sıkışıklığı, Gecikme süresi maliyeti. Master of Science in Civil Engineering. Thesis (M.S.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Civil Engineering, 2014. Supervisor: Assist. Prof. Dr. Mehmet Metin Kunt.

Abstract

This study primarily investigates the combination of a microscopic traffic flow simulation and a crash prediction model to develop effective surrogate safety assessment measures at signalized urban intersections. This approach enables the early identification of safety risks in traffic flow and can be utilized for risk assessment of different traffic sites as part of road safety audits by identifying the probability of several accident types. Nevertheless, resulting individual vehicle accidents can only be investigated in detail in nanoscopic accident and vehicle crash simulations that allow the consideration of detailed vehicle dynamics and therefore estimations of collision severity. Hence, the second objective of this study is to combine the existing simulation methods to provide a tool able to analyze critical traffic situations. Furthermore, the tool is also capable to evaluate the pre-crash phase and to assess the effectivity of Advanced Driver Assistance Systems such as Autonomous Emergency Braking.

Abstract

Transit Signal Priority (TSP) provides preferential treatment for public transit vehicles at signalized intersections when implemented. TSP is usually provided by interrupting the typical signal timings and extending the green or truncating the red for the signal phases that serve transits. This study investigates the impact of implementing a TSP treatment along a major arterial. A microsimulation approach was used to model, assess, and evaluate the potential benefits of implementing this treatment to bus transit vehicles. The network was built in a VISSIM multimodal microsimulation environment to test the traffic network performance with and without priority treatments. The study considered different peak hours for performance assessment. Three transit routes were considered in the microscopic modeling. The results showed a significant benefit of implementing TSP for the transit vehicles. The travel time was reduced by more than 40% in some cases, which can be translated into lower transit delay and more reliable transit service. The results also showed that TSP has a minimal negative effect on the general traffic. In fact, the general traffic along the studied transit routes benefited from the TSP implementation because of the better traffic progression and additional green times. 2018 The Authors. Published by Elsevier B.V. This report was made possible by UREP award (UREP18-054-2-020) from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopu

Abstract

"jats:p"Pedestrian level of service (PLOS) is an important measure of performance in the analysis of existing pedestrian crosswalk conditions. Many researchers have developed PLOS models based on pedestrian delay, turning vehicle effect, etc., using the conventional regression method. However, these factors may not effectively reflect the pedestrians’ perception of safety while crossing the crosswalk. The conventional regression method has failed to estimate accurate PLOS because of the primary assumption of an arbitrary probability distribution and vagueness in the input data. Moreover, PLOS categories in existing studies are based on rigid threshold values and the boundaries that are not well defined. Therefore, it is an important attempt to develop a PLOS model with respect to pedestrian safety, convenience, and efficiency at signalized intersections. For this purpose, a video-graphic and user perception surveys were conducted at selected nine signalized intersections in Mumbai, India. The data such as pedestrian, traffic, and geometric characteristics were extracted, and significant variables were identified using Pearson correlation analysis. A consistent and statistically calibrated PLOS model was developed using fuzzy linear regression analysis. PLOS was categorized into six levels ("jats:italic"A"/jats:italic"–"jats:italic"F"/jats:italic") based on the predicted user perception score, and threshold values for each level were estimated using the fuzzy "jats:italic"c"/jats:italic"-means clustering technique. The developed PLOS model and threshold values were validated with the field-observed data. Statistical performance tests were conducted and the results provided more accurate and reliable solutions. In conclusion, this study provides a feasible alternative to measure pedestrian perception-based level of service at signalized intersections. The developed PLOS model and threshold values would be useful for planning and designing pedestrian facilities and also in evaluating and improving the existing conditions of pedestrian facilities at signalized intersections. Document type: Article