Toplu ulaşımda sefer ve zaman planlaması için çok kriterli bir optimizasyon modeli
A multi-criteria optimization framework for bus scheduling in public transportation
Yazar: SALİM YILMAZ
Danışman: DOÇ. DR. SEDA YANIK ÖZBAY
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Endüstri Mühendisliği Ana Bilim Dalı / Mühendislik Yönetimi Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Endüstri ve Endüstri Mühendisliği = Industrial and Industrial Engineering

Özet:
Dünya nüfusunun büyük çoğunluğu şehirlerde yaşamaya başladığından dolayı, artan hareketlilik ihtiyaçları, trafik sıkışıklığı ve karbon emisyonları gibi konular önem kazanmaktadır. Tüm bunlara ek olarak, pazardaki değişen dinamikler vatandaşların konforlu ve kaliteli bir ulaşım hizmeti beklentisine itmektedir. Bu nedenle, toplu ulaşım hizmeti sunan şirketlerin ve araştırmacıların, bu hususları göz önünde bulundurarak sürdürülebilir ulaştırma çözümleri üretmeleri gerekmektedir.
Şehiriçi ulaşımda verimli planlama çözümleri sunmak için, toplu taşımada kullanılan otobüslerin zamanlama problemini ele alıyoruz. Büyük metropol şehirlerde, toplu ulaşım ağları çok büyüktür. Bu nedenle, gün boyunca değişen talep, trafik sıkışıklığından dolayı hizmetlerin planlanması zordur ve kıt kaynaklarında en iyi şekilde kullanılması gerekmektedir. Bu çalışmada, bir otobüs hattının optimizasyonu için bir doğrusal programlama matematiksel modeli hazırladık. Problemimiz, belirli bir otobüs hattındaki talep farklarını dengelemek için kısa dönüşlü ve tam tur seferler için optimal frekansların belirlenmesidir. Matematiksel model formülasyonumuzda iki amacı göz önünde bulundurduk: (i) sağlanan hizmet kapasitesi ile talep arasındaki farkın en aza indirilmesi; ve (ii) yolcu bekleme ve seyahat süresinin en aza indirilmesi. Bu iki hedefi tek bir hedefe indirgemek için, ağırlıklandırma yöntemini kullanarak her bir hedef için anlamlı ağırlıklar elde ettik. Sağlanan hizmet kapasitesi ile talep arasındaki fark olan ilk amaç, işletme perspektifinden işletme maliyetinin en aza indirgenmesi ve yolcu açısından ise konforun değerlendirilmesidir. İkinci amaç, yolcu seyahat ve bekleme süresi, operatör perspektifinden müşteri memnuniyeti kriterleri ve yolcu açısından faydanın değerlendirilmesidir. 
Dünyanın en büyük şehirlerinden birisi olan İstanbul'da 15 milyon nüfuslu bir vaka çalışması ile kurduğumuz modeli test ettik. İstanbul'da otobüs toplu taşıma hizmeti veren İETT'den kapsamlı bir veri seti elde ettik. Kullandığımız veri seti, İstanbul'un en uzun hatlarından birisi olan 500T hattı ile ilgilidir. 500T numaralı otobüs hattı, toplamda 79 duraktan oluşmakta ve gün boyunca yoğun şekilde kullanılan bölgelerden geçmekte ve  otobüsler genellikle kalabalıktır. Bu sorunların üstesinden gelmek için, optimum kısa dönüş ve tam tur hizmet veren alternatif seferlerin frekanslarını belirlemek için matematiksel programlama yaklaşımını kullandık. Gerçek hayattaki verileri kullanarak modelimizi uyguladık ve matematiksel modelimizi GAMS optimizasyon programında CPLEX çözücüsünü kullanarak çözüyoruz. Ayrıca pareto-optimal çözümleri de sunuyoruz.

Abstract:
As the vast majority of the world's population has started to live in cities, issues such as increased mobility needs, traffic congestion and carbon emissions are becoming important. In addition to all of these, the changing dynamics in the markets push the citizens into the expectation of transportation service in a comfortable and high quality manner. Thus, the companies providing mobility and the researchers are required to produce sustainable transportation solutions considering these issues.
Istanbul is a city that has been receiving immigration for many years and therefore is constantly expanding with the demand of new residential areas. With the establishment of new settlement areas, both the population density at the central points in the city increased, and the city grew linearly with the establishment of new settlement areas in the east and west axes. As a result of this expansion, a distance of approximately one hundred and fifty kilometers has been formed between the eastern and western borders of the city and with the demand for transportation in these settlements, the city has been faced with a very complex journey in terms of transportation. Due to the high demands for travel in the city, the geographical structure being rugged and the long distances, the difficulty level of the problems faced by the city managers increased and transportation emerged as the most important problem of the city.
In order to meet the transportation demand in Istanbul, almost all modes of transportation from the past to the present have been put into service in accordance with the geography of the city and this demand has been tried to be met. The demand for transportation between the sides of the city was primarily provided by sea transportation between the coasts of the city; however, despite the increasing demand for travel over the years, the construction of new bridges, the increase in the number of ships serving and the increase in size, the demand for travel between the two sides has not been achieved with the desired comfort level. In addition, there was no solution to the resulting traffic problem. On the other hand, the rubber wheeled transportation network expanded in this process, started to carry the largest percentage of the transportation network in Istanbul and became one of the most widely used transportation systems in the world.
The changes in the transportation sector in recent years and the density of the transportation networks in the major metropolises constituted the subject of this thesis. The timing problem of buses used in public transport is the main focus of this thesis. Again in the literature research, a study that used the techniques used in this study was not found. In this study, a mathematical model of linear programming has been prepared. With the developed mathematical model, the aim is to minimize the difference between service capacity and demand and to minimize passenger travel and waiting time. In the end of all these studies, it is aimed to establish a mathematical model considering both demand differences of a bus line by using the techniques mentioned above.
Rubber wheeled systems are the most dynamic modes of public transportation in Istanbul with their different transportation modes and numerous variables. Buses, minibuses, taxis, taxi minibuses and services in rubber wheeled systems mode; it is the most difficult mode to manage due to the large number of vehicles and consequently the number of individual operators.
In the literature research conducted within the scope of this study, evaluations have been made about the studies on line balancing especially in different countries and with different purposes. At this point, although the foundation of the related models was laid in the early 90s, the basic acceleration and growth in the literature began to be seen at the end of the 2000s. In this study, various publications between 1997 and 2017 were examined. In addition to these, especially in recent years, it has been observed that the studies in this field have increased in recent years thanks to the developments in data mining techniques and infrastructure developments that facilitate the analysis of big data. As a result of the study, it was seen that certain techniques (eg stochastic models) were concentrated in the studies.
To provide efficient planning solutions for the transportation in cities, we deal with the scheduling problem of the buses in the public transportation. In large metropolitan cities, the bus network is very large. Thus, planning of services is difficult due to changing demand throughout the day, traffic congestions and the need to use the scarce resources optimally. In this study, we formulate an integer-programming for the optimization of a bus line. The problem seeks for the solution of optimal frequencies of a specific bus line's various short turn and complete trip alternatives that are used to balance the demand differences between the links of the line. We consider two objectives in our model formulation: (i) minimization of the difference between the provided service capacity and the demand; and (ii) passenger travel and waiting times. In order to reduce these two objectives into a single objective. The first objective, namely difference between the provided service capacity and the demand, is evaluated in terms of the criteria of operating cost minimization from the operator perspective and comfort from the passenger perspective. The second objective, passenger travel and waiting times are evaluated in terms of the criteria of customer satisfaction from the operator perspective and utility from the passenger perspective. 
We present a case study in Istanbul which is one of the largest cities of the world with a population of 15 million. An extensive dataset is obtained from IETT that provides the bus public transportation service in Istanbul. The dataset that we use is related to one of the longest lines of Istanbul with the line number, 500T. The bus line, 500T has almost 79 stops and travels through highly congested links throughout the day. Moreover, the buses are commonly over-crowded. To overcome these problems, we use mathematical programming approach to specify optimal short-turn and complete trips and their frequencies. Using the real-life data, we implement our model and solve it using CPLEX. Moreover, we also present the pareto-optimal solutions and goal programming solutions.