A new approach for operation of intersections with presedence of bicycle

Nowadays, traffic problems are considered of the most significant challenges that face most countries around the world. Rapid growth of population, unplanned expansion of cities and increased use of motor vehicles increase the environmental pollution and negative climate changes. All of these affect both human health and the city life negatively and thus lead to many problems that reduce the quality of life. In city centers, practically, bicycles are considering consider as an ideal solution for area's problems such as traffic congestion, lack of parking places and increasing in air pollution. However, in order to obtain its benefits, specific planning and design of bicycles' run-ways should be developed. Nowadays, there are about one billion bicycle users around the world and with each car there are three bicycles are being produces simultaneously. Last years, our country suffers from severe problems related to increasing in traffic congestion, lack of parking places and increasing in air pollution. Specially in Istanbul as a megacity, bicycling has a very high potential of success as an alternative solution for the city's transportation problems if government provides required infrastructure and encourages people to use it. From an economic view point, cost of a bicycle road is about %10 of a normal highway and about %2 of a motor-way. However, environmental negative impacts that associated with motor vehicles have been estimated to be about 60 million tons on average. All of these factors express that bicycling is a very important player in solving traffic and transportation problems. However, governments pump considerable portions of national income into transportation projects to mitigate the negative economic and environmental impacts of traffic congestions. One of the most well-known measurements is supporting the use of bicycle which provides more sustainable solutions in terms of economic and environmental aspects. Especially for short distances, the bicycle has a competitive features compared with motor vehicles. Notably, bicycle use acquires considerable portions in many countries around the world. In Turkey, bicycles are not preferred as a transportation mode and they are not widely used. Nevertheless, the developments in transportation technologies (e.g. intelligent transportation systems) can enable us safely and effectively operate bicycle routes from high density traffic areas (e.g. city centres) to different residence areas around the city. The most proper control system of bicycles at intersections with high motorized traffic volumes, especially at peak hours, is the using of traffic signals (traffic lights) which achieves the required safety for road users. In 2014, Istanbul Development Agency with participation of ministry of development have prepared guide lines for representing a bicycling road network in Istanbul city under a name of "A Guide for Safe Bicycle Roads Application in Istanbul City". In this report, data related to the accidents that bicycle users exposed to is pointed as results of the carried out surveys. Among all users, about %42.9 reported that accidents result from interaction with motor vehicles while %37.1 of them pointed that their accidents came from collapsing with pedestrians at intersections. In the light of these results, in order to decease accidents and increase safety for bicycle users, points of intersect with motor vehicles and pedestrians should be safely controlled. Especially, when traffic volumes being high at peak hours, it is must to control crossing of motor vehicles, pedestrians and bicycles through traffic signals to avoid accidents and provide safety to all road users. For any signalized intersection, the most important factors that determine proper timing are delays and number of stops. These factors determine the level of service of intersection which must ensure an acceptable saturation volume. In order to achieve this, a mathematical model that compute signal's times according to intersection saturation level should be used. In the context of the case study, the results have been obtained through constructing a microscopic traffic simulation model for a test road network that takes place in Bakirkoy district and consists of three main streets which are Aksu St., Ekrem Kurt St. and Çobançeşme Koşuyolu St. The reasons that motivate us to choose this region as a case study are: (1) according to the questioners that were conducted under the context of Istanbul transportation planning, individuals have been found to have more inclination towards using the bicycle mode through the test network (2) that route connects two main significant arterials which are Coastal Road and the D-100 Transit Road, (3) good accessibility to different public transport systems. However, under the purpose of the thesis, the selected network includes three signalized intersections which operationally, geometrically and physically differ in their properties. These differences will enable us to categorize the evaluation process under different intersection situations. In order to determine peak hour in the study area, traffic counts for specific intersections which provided by Istanbul municipality have been analyzed and afternoon peak hour has been found to have maximum traffic volumes. Therefore, all traffic counts have been collected in the afternoon peak. In order to attain that, at each intersection, number of video recording have been obtained for at least two hours around the afternoon peak hour. Aftermath recording videos have been analyzed and traffic volumes for each vehicle category have been counted. In addition to traffic volumes, traffic signals' timing (e.g. number of phases, green time, etc.) have been observed for each intersection within the study area. Thus, the collected data have been used to construct and calibrate the traffic microsimulation models that represent current condition of the study road network (do nothing scenario) through VISSIM and AIMSUN software. The calibration process has been achieved through two main stages. In the first stage, the two models have been calibrated visually by achieving acceptable movements of vehicles with logical interactions and rational queue lengths. In the second stage, models have been calibrated analytically by comparing the exiting traffic volumes with the actual ones. Different scenarios have been adopted with gradual shifting from motor vehicles' travels to bicycle mode with portions of 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%and 20%. The number of travels that are shifted to bicycle and the associated number of motor vehicles (reduced number of motor vehicles) have been determined by using occupancy rate of diffrent mode which is mentioned in Istanbul Transportation Master Plan 2011. Aftermath, in order to capture the network and intersections performance related to each scenario, the test network has been introduced in two different microscopic simulation models by using VISSIM and AIMSUN software packages. For each scenario, the impacts that associated with the shifting rate such as number of motor vehicles, number of bicycle, signal phasing and timing, etc. have been introduced to the calibrated simulation model. The results that are obtained from the two models show that, a shifting in motor vehicles' travels of 10%is attaining an optimum network and intersections performance (optimum point). Additionally, 10%increase and 10%reduction of the private car occupancy value that obtained from the Istanbul Transportation Master Plan for the study area were also tested within the scope of the thesis. The proposed methodology has been applied separately for each changing case of occupancy rate. The results indicate that, for both cases, optimum number of bicycles still at shifting in motor vehicles' travels of 10%which attaining the optimum network and intersections performance. Consequently, the relationship between the optimum number of bicycle and traffic volume at intersections has been formulated. Additionally, a relationship between the optimum number of bicycles and the optimum green time of signals specified on intersections' physical properties has been constructed, so that the results obtained in the study can be used at similar intersections. In the two simulation programs, the do nothing case (i.e. current situation) has been modelled and calibrated. Then, simulation programs for the proposed 10 scenarios have been run 10 times and average values were obtained. From 75 simulation minutes, the first 15 minutes have been eliminated and the analyses of the later 60 minutes have been considered where the system was expected to become saturated. The computational outputs of the models contain; average speed (km / h), total travel time (h), total distance (km), total stopping delay (h), average stopping delay (sec), total stopping number, average stopping number and average delay (sec) values. In addition, VOC (g), CO (g) and NOx (g) values were found for each scenario using data collection points (nodes) at medium junction lengths (m), maximum queue length (m), fuel consumption (gal) and emission values. The use of the bicycle as a transport mode makes it crucial to set the signal timing of cycling at intersections, where the performance of signalized intersections depends on traffic factors related to the saturation volume of passenger car unites as well as on environmental factors such as fuel consumption and emissions. In the light of results, it has been demonstrated that, the increasing in number of bicycles at the intersection with an unplanned signal is more harmful to the environment. In this respect, the volumes of motor vehicles at intersections must be determined and the optimum number of bicycles corresponding to this volume should be concluded via the methodology obtained in the thesis. Another interesting finding in this thesis is the relationship constructed between the optimum number of bicycles and the optimum green time ratios (i.e. of total cycle length) which can be used to conclude the green time of similar intersections with different traffic volumes. That is, by using the optimum green ratio at optimum number of bicycles, the maximum saturation flow of intersections will be achieved, and the harmful effects of the emission values of the motor vehicles and the fuel consumption will be minimum. If the number of bicycles exceed the optimum volume at the junction, the bicycle phase intersection must be kept constant and, if necessary, bicycles should be kept and stored in safe areas. Finally, the negative effects of the phase times applied to the volumes below and above the optimal values can be analysed using the diagrams derived in the thesis. Considering bicycle routes in urban areas, Amsterdam is one of the first cities in the world that comes to mind where they separated movements of bicycles of other motor vehicles by using bridges. In line with the analysis done in the thesis, the negative environmental and economical effects of increasing bicycle volume at at-grade intersections are being removed. Especially in recent years, the application of the cycling roads, which takes intensive efforts of our country, will negatively affect the performance of at-grade intersections as the number of bicycles increase. Therefore, the use of the results of the thesis will provide important contributions in the forthcoming period.