Kentiçi ulaşımında otobüs öncelikli sistemler ve İstanbul'da Taksim-Zincirlikuyu otobüs yoluna model uygulaması

Abstract

Ellili yıllarda başlayan sanayileşme ve yetmişli yıl lardaki petrol krizi ulaşım sorunlarını ve toplutaşım kul lanımını ön plana getirmiştir. Otobüslere karna trafikli yollarda Öncelik verilmesi veya özel yol tahsisi sonucunda hızlı, etkin, ekonomik bir toplutaşım hizmeti gerçekleşti rilirken yolculuk modunun bir ölçüde ezel araçdan otobüse geçmeside sağlanmaktadır. Ayrıca otobüs yolu projelerinde ekonomik verimliliğin esas alınması yanısıra yol güzergah ları çevresinde, kentsel alanlarda daha iyi çevre koşulla rı sağlanmaktadır. 1979 yılında İstanbul'da Taksim-Zir^cirlikuyu güzer - gahmda otobüs yolu uygulamasına geçilerek, işletmenin sefer sayısında, katedilen kilometrede, taşman yolcu sa yısında ve gelirinde artış sağlanmıştır. Ancak daha sonra otobüs yolundaki hat ve araç sayısını.-, arttırılması sonu - cunda yolun kapasitesinin üzerinde çalıştığı uygulanan matematik model ile tesbit edilmiştir. Bu çalışmada yolun daha ekonomik ve daha etkin işle timinin tekrar sağlanması ve hizmet seviyesinin yükseltil mesi için bir dizi işletme değişikliği ile fiziksel düzen lemeler önerilmektedir. Önerilerin getireceği yararlar ça lışmada gösterilmiştir. Ancak bu koridorda hızlı ve verim li ve yolcu artışına yanıt verecek köklü çözür., raylı sisteme geçiş olmaktadır.

This study mainly discusses urban transportation problems, solutions through bus priority measures and analyses Taksim-Zincirlikuyu bus lane in Istanbul Metropolitan Area. The dissertation includes an introductory, six main chapters and conclusions. As an introductory, the first chapter discusses the importance of transport problems. The two main factors that cause transportation problems are the industrialization process and widely usage of the private cars in the city centers. Rapid population growth, physical expansion of cities and the fact that fuel reserves will be exhausted at the end of the century makes this problem more vital. The traffic congestion that occurs in the morning and evening peak hours creates many problems such as; time loss, excess fuel consumption, air, noise pollution, accidents, work power loss and others. The petroleum crisis in seventies and the shortage of fuel caused public transportation gain importance over private car usage. In most of the developing countries many measures are taken in order to meet the high demand of urban transport. In order to increase the productivity of transportation systems, transit priority measures are taken. Buses carry more people than other vehicles in the use of road space and efficiency of the transportation system in a city can be improved just by giving priority to buses over other vehicles. Using the transit measures increases the speed of buses, trips, passangers carried and decreases fuel consuption thus produces net economic benefit. Also when the transit services improved by usage of transit priority then private car owners tend to use public transport services and that is benefical in energy conservation. At the same time some environmental improve ments, in areas where transit measures are taken, is used in order to make urban areas more pleasant. In the second chapter the aim and types of bus priority systems are defined in detail. The increased usage of private cars, decentralization of industry and suburbanization decreased the efficient use of bus travel. The usage of private cars caused congestion thus sloved down the bus xv services. In order to improve the public transport services some measures are taken which covers the application of priority measures to buses over other vehicles. The priority measures can be classified under three main items; physical, operational and legal. The physical priority gives separate lanes to buses where the traffic congestion is high. Most common types are; with-flow bus lanes, contra-flow bus lanes, reserved lanes on freeways, busways. The operational priority measures cover the priority given to buses in mixed flow conditions. Some applications for this type are; turning priority to buses at intersections, separate islands for bus stops, priority at traffic signals. The legal priority measures cover, to give priority to buses leaving the bus stop in entering the mixed traffic, to put parking prohibition at bus stops. The most commonly used bus priority schemes are discussed in detail. With-flow bus lanes are the most common transit priority techniques. These are the lanes reserved for buses travelling in the same direction as the general traffic. Contra-flow bus lanes are the lanes for buses to travel in the opposite direction to that of the normal traffic. Reserved bus lanes on freeways are used for transit and other highoccupancy vehicles. Bus-only streets are restricted to the use of pedestrians and public transport vehicles, they are also called transit mall. Limited classes of other traffic such as bicycles, emergency vehicles can use these streets. Priority at traffic signals are applied to give priority to transit vehicles and to reduce the delays that occur at the traffic signals. The main aims of bus priority systems are to give better operating conditions for buses and to provide better service to passengers. The movement of people is considered as a primary aim in urban transport planning. The economic effects of bus priority schemes can be stated as; changes in walking, waiting and 'riding times of passengers, changes in travel-times öf non-priority vehicles, changes in bus operating costs, changes in number of accidents. The social and environmental effects are; effect on modal-split, fuel conservation, changes in atmospheric pollution and in noise levels. Thus priority measures free the buses from the effects of congestion and provides efficient services. In economic terms because of high speeds attained, savings in passenger time and operating costs are established. Also by changing the model split in favour of public transport energy conservation can be provided, environmental improvements are made around the priority schemes and a better image of public transport is attained among the users of bus services. In third chapter urban transportation in Istanbul Metropolitan Area and IETT General Directorate's public transportation services are discussed. As in many developing countries the industrialization process brought with itself the urbanization problem in Turkey after year 1950. There XV i exists great population increase in Istanbul. The population of the city's central core (CBD) expanded, accordingly the population of suburbs grew rapidly and still growing.. Istanbul is being the biggest city of Turkey has population over 6 million and it increases 200.000 - 250.000 every year. As in other big metropols Istanbul faces with urbani zation and transportation problems. The main roads in the city are narrow and the secondary roads are limited. Since Istanbul is a historical city it is very difficult to open new roads. The inadequacy of local public transport systems brought forward paratransit services. These community cars together with high usage of private cars create traffic jams in the narrow streets of the city. In 1985, Istanbul's share of transport modes in carrying passengers can be given as; private car 17.40 %, taxi 6,59 %, shared-taxi (dolmuş) 2.59 %, İETT 23.13 %, blue-buses 11.22 %( minibus 25.18 %, other 0.90 %, suburban railway 5.92 % and maritime lines 6.0 7 %. IETT General Directorate performs public transport services in Istanbul Metropolitan Area covering 2500 km^. Many measures has been taken for efficient mass transporta tion in city such as buying new buses, to put money-box system, usage of monthly travel card, to put express services. In the fourth chapter, Taksim-Zincirlikuyu bus lane which is the first bus lane application in Istanbul is discussed. There exists mixed type of vehicles having different operation characteristics for transportation purpose in the city. Since buses share same roads with paratransit and private vehicles, their commercial speeds are very low. This extends the bus trips, decreasing the number of trips that can be attained during the day, thus decreases number of passengers carried and income of the operation. Taksim-Zincirlikuyu is an arterial road in central business district area where the traffic congestion on the route increased continiously and buses traveled with speed of 6 km/h forming long queues. In order to provide effective and economic bus services a bus lane of 5 km. long was opened in 1979, The bus lane begins at Taksim and through Elmadağ, Harbiye, Osmanbey, Şişli, Mecidiyeköy, ends at Zinc irl ikuyu. IETT made some route changes, new bus-stop locations, formed Mecidiyeköy as a transfer center for this bus priority application. Many positive results of bus lane system were achieved mainly; in a very congested zone the buses could travel effectively, the operational speed of buses were increased, fuel consumption was reduced, number of passengers carried were increased, income of bus services were increased, a new transfer center at Mecidiye köy lessen the congestion of Taksim. After a month of its opening the passengers carried was increased by 27 % and income increased by 2 8 %, on the 62 routes which used Taksim-Zincirlikuyu bus lane. xvii The number of passengers carried on Taksim-Zincirlikuyu route was 4000 passenger/h before the application of bus lane system, this number increased to 6000 passengers after the application. The' buses took the route in 50 minutes, shared-taxi (dolmuş) in 20 minutes, private cars in 18 minu tes after the application of the bus lane system this values were 2 0 minutes for buses, 15 minutes for shared-taxi (dolmuş) and 13 minutes for private cars. In the fifth chapter, a mathematical model is applied to bus lane to find maximum flow rate. First the relations hips among the three variables; speed (u), density (k) and flow (q) which is called a traffic stream model % "q=uk" is discussed. Two specific points exsists on the model; as concentration and flow approaches zero the mean speed approaches the mean free-flow speed, uf, and as concentration approaches its maximum value called jam density, kj; speed and flow approaches zero. qm is the maximum flow rate, um is the speed at which the flow rate is maximum and km is the density at which the flow rate is maximum. Then the speed-density, speed-volume and density-volume relations are stated. The model used in the study is Greenshield1 s speed- density model, "u=uf (1-k/kj)". This is a linear relationship where uf is the free-flow speed and kj is the jam density. This model is simple to use and good correlation is found between the model and field data. The maximum flow rates (section capacities) at Taksim, Şişli, Zihcirlikuyu section of the bus lane at north and south bounds are calculated by using the model. These estimated maximum flow rates are compared with the actual morning, noon and evening peak-hour bus volumes which uses the bus lane at these sections. This comparison showed that during the peak periods at Taksim section of the bus lane, the bus volumes are over the capa- ' city values giving, F level of service. At Şişli section the bus lane operates at E and F level of services. At Zincirli- kuyu section it showed D and E level of services. Another analysis for the bus lane is made with respect to passenger capacity. The people per hour that can be served by varying bus flow rates are compared with the actual passengers that are carried on the bus lane at Taksim, Şişli, Zincirlikuyu sections on south and north bounds at morning, noon and evening peak periods. This analysis showed that passenger level of service on the bus lane varied between C, D and E and at two sections F level of service was observed. Finally peak-hour factors of Taksim, Şişli, Zincirlikuyu sections of the bus lane are determined. The peak-hour factors reached to 0,90 in some sections but on average it is around 0.80. In the sixth chapter the present situation of Taksim- Zincirlikuyu bus lane is analysed with respect to its operational and economical aspects. The bus lane analysed for the years 1979, 1982, 1985 and 1987 and it is seen that the number of routes and buses increased continiously. Also xviii the articulated buses and private blue buses began to use the lane. The yearly time-tables showed that at some sections of the bus lane, the number of buses increased by hundred percentage and routes increased by forty percentage. The bus lane became congested forming long queues of buses thus delays at bus-stops and intersections increased gradually. In the end the speed of buses, number of bus services, passengers carried are decreased, fuel consumption increased and finally the operational cost of bus services increased. The operational cost depend upon the degree of system use composes from fuel, oil, tire and vehicle maintenance costs. The operational costs increase as the speed of vehicles decreases and the budget of the public transit services is effected adversely. The bus lane analysed with respect to its operational speed during 1985 and 1987 years. It is seen that the speed decreased up to forty percentage within the two years. Another analyses in made for the delays at bus stops and intersections. It has seen that at some bus stops of Taksim- Zinciri ikuyu bus lane, buses waited more than a minute. These results showed that the priority scheme has lost its aim and that efficient services and economical benefits of the bus lane couldn't be attained any more. In the seventh chapter some solutions are put forward inorder to increase the efficiency of Taksim-Zincirlukuyu bus lane. As a first solution a new route plan is proposed which will reduce the number of routes and buses using the bus lane. In this new plan, bus transfer centers will be formed around Zincirlikuyu and Mecidiyeköy districts and passengers will transfer to main routes that will use the bus lane. Twelve main routes are proposed for this plan and gradually the number of buses using the bus lane decreased. As a second solution the physical improvements of the bus lane is discussed. Some bus stops are cancelled and new traffic management applications are proposed. As a third solution some techniques which are used in other countries for making bus lanes more efficient are stated. Bus convoy system allows buses to operate like a train, a group of buses stopping and departing together at the bus stops. This convoy system increases the capacity of single bus lanes. Another scheme is express trunk line where the passengers will transfer to special higher capacity trunk buses at the bus terminals. The trunk lines on the main corridor will run without stops till it reaches the specific section of the corridor which it is serving. As a final solution for Tak sim- Zinciri ikuyu bus lane, usage of rail system is proposed. The bus lane is saturated at its present stage and operating over its capacity. The passengers carried at peak hours is above 12.000 pas senger/hr /lane which indicates that bus system is neither efficient or economic to use. Also Tak sim- Zinciri ikuyu bus lane is on the proposed route of Yenikapı-Ayazağa metro system. Since 1907 several projects are made and proposed metro construction on this route. xix In the eighth chapter the solutions are summarized to make Tak sim- Z inciri ikuyu bus lane efficient and ecnomical again* Among these solutions are; to apply a new route design to improve the operation condition of the busway,to cancel some stops inorder to improve the physical condition of the lane, to give priority to buses at signal ization system at the intersections of the bus lane by this way the time and fuel loss can be decreased, application of advanced ticketing systems inorder to prevent the long queues of buses at bus stops. The model study and present situation of Taksim-Zincirlikuyu bus lane shows that the new route design and physical improvements can increase the capacity of the lane for a time but the final solution is to apply a more advanced transport system such as rail system.