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Yayın Bariyerli otoyol gişelerinin trafik akımına etkisi: İstanbul Kuzey Marmara Otoyolu örneği(Osmaniye Korkut Ata Üniversitesi, 2022-07-30) Aksoy, Göker; Çakıcı, ZiyaBu çalışma bariyerli, nakit ve otomatik ödeme sistemlerinin birlikte kullanıldığı otoyol çıkış gişelerinin trafik akımına olan etkisini ele almaktadır. Gişelerde, nakit ödeme yapan sürücüler tamamen durarak ödemelerini yapmakta, otomatik ödeme sistemine sahip olan araçlar ise hızlarını düşürerek ve yalnızca bariyerin açılmasını gözeterek geçiş yapabilmektedir. Ayrıca, sürücüler, karma ödeme sistemlerinin yanında farklı araç tiplerinin kullanımıyla da artan servis süreleriyle karşı karşıya kalmaktadır. Bu çalışma kapsamında, gişelerdeki servis süreleri, İstanbul Kuzey Marmara Otoyolu‘ nun Alemdağ gişeleri göz önünde bulundurularak, VISSIM benzetim programı ile farklı senaryolar altında incelenmiştir. Analizler sonucunda, otoyol ücretinin nakit ödenmesi durumunda servis sürelerinin araç tipine göre değişiklik gösterdiği ve bu sürelerin 6.1 sn ile 66 saniye arasında değiştiği görülmüştür. Bununla birlikte, talebin düşük olması durumunda, ardışık otomatik ödeme sistemini kullanan taşıtların birbirine etkisinin neredeyse bulunmadığı, nakit ödeme yapan kullanıcıların ise diğer taşıtlar üzerinde önemli etkileri olduğu tespit edilmiştir. Sonuç olarak, 2000 tşt/sa/şrt‘ lik talep olması ve tüm taşıtların nakit ödemeyi tercih etmesi durumunda 48 dakikalara varan gecikmelerin yaşanabileceği bulunmuştur.Yayın İstanbul çevre yollarında yağmurun serbest akım hızı ve kapasiteye etkisinin irdelenmesi(TMMOB İnşaat Mühendisşeri Odası, 2019-10-12) Aksoy, Göker; Öğüt, Kemal SelçukTrafik tıkanıklığının en çok yaşandığı kentimiz, 15 milyondan fazla nüfusuyla şüphesiz İstanbul’dur. İki önemli anayolu (D100 Karayolu ve O2, O3, O4 Otoyolları) üzerinde, zirve saatlerde yapılan yolculukların daha uzun sürdüğü sürücüler tarafından benimsenmiş bir gerçektir. Aynı zamanda, yağmur gibi sürücü davranışını değiştirebilen çevresel bir dış etmenin tıkanıklığın etkilerini daha da arttırdığı tecrübe edilen bir durumdur. Ayrıca, otoyol gibi yüksek hızların yapıldığı yerlerde, diğer taşıtların sebep olduğu ıslak yol yüzeyinden havaya kalkan yağmur suları da görüşü olumsuz etkileyerek sürücülerin benzer şekilde tepki vermesine neden olur. Kısacası, insan algısının bir sonucu olarak izleme aralıkları yağmur etkisiyle artar, hızlar düşer. Kuşkusuz her sürücü benzer tepkiyi vermeyeceğinden, yolu kullanan taşıtlar arasındaki hız farkları yağışsız günlere göre daha da artacak ve artan hız farklarıyla yol daha güvensiz olacaktır. Bu çalışmada, İstanbul’un önemli çevre yolları olan, O2, O3, O4 Otoyolları ve D100 Karayolu üzerinde trafik akımının yağmur etkisi altındaki değişimi incelenmiştir. Çalışma alanı kent içi bölgede kalan, kapasite akımının ölçüldüğü, tıkanıklık sorunun yaşandığı bölgelerle sınırlandırılmış ve otoyollarda 50, D100 Karayolu’nda ise 62 km’lik bir bölge incelenmiştir. Trafik algılayıcılarıyla toplanan trafik akım verileri, meteorolojik verilerle birlikte değerlendirilmiştir. Toplam 7 farklı meteoroloji istasyonu ölçümleri 25 farklı trafik algılayıcısı ölçümleriyle eşleştirilmiş ve çözümlemelerde yer almıştır. Güneşli ve yağmurlu günler arasında trafik akımındaki farklılıklar açığa çıkarılmıştır. Yağmur etkisi altında, otoyollarda serbest akım hızı (SAH) %8,61, D100 Karayolu’nda ise %8,16 azalmış; kapasitenin ise sırasıyla %7,88 ve %9,07 oranlarında azaldığı bulunmuştur. Ayrıca boyuna eğimin artması her iki yol tipinde de SAH’ı azaltmakta, kapasite ise artan boyuna eğim ile birlikte yalnızca otoyollarda azalmaktadır.Yayın Pedestrian crossing behavior at midblock crosswalks(Elsevier Ltd, 2019-12) Tezcan, Hüseyin Onur; Elmorssy, Mahmoud; Aksoy, GökerIntroduction: This study investigated the pedestrian crossing behavior at midblock crosswalks, in Istanbul. Method: Data were compiled from field studies at four selected crosswalks that were on one-way streets. Three of the crosswalks were located on three-lane streets while the other one was on a two-lane street. By using two-hour video recordings at each crosswalk, information was collected about pedestrian crossing preferences, pedestrian platoons both at curbside and during the crossing, traffic characteristics including volume, crosswalk occupancy and illegal parking, and pedestrian characteristics comprising age, gender and distraction status. These data were stratified with respect to the number of lanes and two multinomial logit models for platooning and individual crossing behavior was estimated for each stratum. Results: The results showed that the likelihood of platooning increases as the traffic volume and platoon size increase. Moreover, pedestrians who waited for little or no at the curbside and started to cross when one or more lanes were occupied generally lost time during the crossing. In terms of policy, the formation of platoons should be prevented by enforcement or demand-responsive traffic signals with push-to-walk buttons, etc. Overall, the study revealed that the presence of midblock crosswalks is questionable.Yayın The investigation of the effect of saturation flow on the average vehicle delay at signalized intersections(Izmir Democracy University, 2021-12-18) Çakıcı, Ziya; Aksoy, GökerSaturation flow (s) is one of the most important parameters used for determining of signal timings at signalized intersections. Therefore, this parameter directly affects the various intersection performance criteria such as queue length, average delay, the level of service and capacity. In this study, determination of the effect of saturation flow rate on the average vehicle delay is aimed. In the scope of the study, firstly, an optimization model which minimizes the average vehicle delay at the intersection is set. Then, a software which optimizes the signal timings at the intersection by using Differential Evolution Algorithm (DEA) is prepared in MATLAB environment. In the second stage, 15 traffic volume scenarios which have different total traffic volume from each other for a four-leg signalized intersection are created in order to test different traffic cases. Created scenarios are classified in 3 groups as Low Volume (LV), Moderate Volume (MV) and High Volume (HV). In the next stage, each scenario is analyzed considering 9 different saturation flow rates (s=1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000 vehicle/hour/lane), separately. In case of implementing of these saturation flow rates, obtained signal optimum timings and average vehicle delay for each scenario are evaluated in details. In the last stage of the study, the average vehicle delays obtained by using s=1800 vehicle/hour/lane which is frequently encountered in many studies in the literature are compared with the average vehicle delays obtained by using other saturation flow rates, relatively. As a result of the comparisons, it is determined that the differences between average vehicle delays are quite low (between -0.9% and +1.2%) in case of Low Volume. In case of Moderate Volume, differences between -20.8% and +37.2% are seen. In case of High Volume, it can be said that the differences change between -41.4% and +116.3%. This situation clearly demonstrate that accurate and faultless measurement of saturation flow rate is quite important in terms of the performance of the intersection, especially in case of moderate and high volume.Yayın Identification of sensor location and link flow reconstruction using turn ratio and flow sensors in an arterial network(Taylor and Francis Ltd., 2024) Taşcıkaraoğlu, Fatma Yıldız; Aksoy, GökerIn this article, a quadratic programming problem is considered to identify all link flows in an arterial network when there are unmeasured link flows. A graphical method is provided to determine the minimum number of measurements and sensor locations required to obtain a fully observable model. It is shown that this method is also valid for the augmented graph with turn ratio measurements. If the minimum measurements required are met, a fully determined network can be obtained. If there is not enough measurement, a bound on the magnitude of the resulting inaccuracy in terms of vehicle kilometers traveled (VKT) can be calculated by the proposed linear programming method. The model is that of a queueing network; the parameters describe network geometry, saturation flow rates, turning ratios, timing plan and link flows. Three case studies are conducted to validate this approach. The first two cases are to calculate all missing flows by using a few numbers of measurements and minimum number of measurements required, respectively. Upper and lower bounds in terms of VKT are also calculated for these cases. Third case is to obtain a fully determined network with the minimum number of flow measurements when turn ratio sensors are included. Real measurements are collected from a network in Mugla including 55 links and 16 intersections. Vissim simulator is used to analyze the accuracy of the link flow calculations obtained from the proposed method. The results show that the proposed programming method can calculate the missing flows with a high accuracy and short computation time.Yayın Examination of delay and travel time at highway toll booths using a micro simulation program: example of Northern Marmara Highway Kurnaköy(2022-04) Özdemir, Ümitcan; Gürsoy, Mustafa; Aksoy, GökerThe aim of this study is to reveal that barrier toll booths are inefficient in terms of delay and travel time when compared to non-barrier toll booths. In our study, Kurnaköy toll booth, on the Northern Marmara Highway, was examined. The toll booth was modeled using the PTV Vissim micro simulation program. Currently, 8 toll booths are in active service and are operated with barriers. As an alternative to the current operation, 4 different operations were modeled: 8 toll booths without barriers, 10 toll booths without barriers, 12 toll booths without barriers and finally 4 toll booths with free passage system. The designed models were run under 3 different demand levels as low, medium and high, and compared using the PTV Vissim program. When the current barrier toll booth and the non-barrier operations were compared with medium demand, it was seen that there is a significant difference in delay. A bottleneck problem was also encountered due to the geometry of the barrier-free toll booth operation. The optimum operation was found by comparing the alternative operations.Yayın Direct usage of occupancy data for multiregime speed-flow rate models(American Society of Civil Engineers (ASCE), 2023-01) Aksoy, Göker; Öğüt, Kemal SelçukEarly macroscopic traffic flow models were based on observations of volume, speed, and density. The invention of traffic sensors has supplied a wealth of data for the development of more accurate macroscopic flow models. However, traffic sensors typically collect volume, speed, and occupancy data. Researchers prefer to convert occupancy to density because of the density usage in earlier models; however, for this conversion, the average length of passed vehicles must be determined. This length is frequently estimated by researchers. However, because the explanatory variable (density) is not observed but produced, this estimation weakens the model results. Considering these challenges, this research proposes a novel traffic flow modeling approach based on occupancy. The proposed method was tested in three speed-flow rate relationship regions, one of which is congested and two of which are free flow. Free flow speed, capacity, queue discharge flow, breakpoint flow rate, and optimum speed can all be determined more precisely with this method. Furthermore, the nonlinear relationship between speed and flow rate was clarified. The proposed traffic flow model is extremely useful, especially for dynamic traffic management applications, because it is based on directly gathered data such as volume, speed, and occupancy.Yayın Investigation of the relationship between upstream and on-ramp flows at downstream capacity level on Istanbul freeway merges(Muğla Sıtkı Koçman Üniversitesi Fen Bilimleri Enstitüsü, 2021-03-04) Aksoy, Göker; Öğüt, Kemal SelçukTraffic congestion usually occurs at freeway merges due to the inequality of lane numbers at upstream and downstream. The freeway entry, defined as on-ramp, is the main cause of this irregularity and in order to clarify its effect, three freeway merges are investigated in this study with macroscopic flow parameters where a variety of geometric properties are present. In each merge, when the capacity flow is achieved at downstream, the on-ramp and upstream flows are determined and the relationship between upstream flow rate and ‘on-ramp ratio’, which is calculated by dividing the on ramp flow rate to the sum of on-ramp and upstream flow rates, is investigated. An inverse relationship is determined between total upstream flows (upstream flow plus on-ramp flow) with respect to on-ramp ratio. As a result, the merge with one lane drop and three-lanes at downstream seems to be least influenced type while the merge with two lanes drop and four lanes at downstream is the highest. For the former, 1% increase in on-ramp ratio causes a reduction of 20 pcu/h/lane on sum of total upstream flows while for the latter 26 pcu/h/lane. It is seen that the term on ramp ratio, can be quite useful variable for establishing capacities of freeway merges with the help of upstream and on-ramp traffic demands.
