Measuring comfort in public transportation: A case study for Istanbul

Congestion in traffic is becoming more and more of a significant problem in metropolian areas, especially due to growing population as a result of various job opportunities provded in big cities. Increase in population causes many problems in security, illegal housing, transportation, education, healthcare and envrionment. In Turkey, especially in metropol cities such as Istanbul, Ankara and Izmir the biggest problem is transportation. There are several reasons that affect transportation. First of them is the increase of highway usage. This comes up with many problems such as traffic jam, traffic accidents and emission increase. Another problem that affects transportation is the increase in urbanization and mobility (dynamism). As a result of rapid and unplanned urbanisation, population and motor vehicle ownership increased so much. Also high consumption of fuel oil in inner-city transportation causes environmental pollution. When we look as a whole, the result of urbanisation comes up with traffric jam and traffic accidents. Another point of view shows that the passenger transportation increased by the improvement in economical conditions. Traffic density increased highly in every mode of transportation. Changes, inventions and developments in industries caused growth of the cities. The growth of the transportation is also increased parallel to the growth of the cities. Growing cities increased the need of transportation and hence traffic jam. Public transportation became a part of the daily activities of the human life. Because of this reason, city managers aim their lifes to be simplified and thir needs to be met. General ideas and operations which are being applied for public transportation, affect passenger's decisions. For this reason, passenger factor should be included to the operations which will be applied by managers. This means a great chance for managers to be able to include passenger experiences to their plans.Increasing car ownership creates a multiplying effect on this problem. Most experts aim to solve congestion problem by encouraging people to use public trasportation. Increased demand for public transport combined with lack of sufficient infrastructure may cause extreme congestion, especially in rush hours. Also due to the preferences of public transportation, passenger density is increasing directly proportional. Especially it is hard to use public transportation at morning and evening busy hours. This leads to significant displeasure for passengers and a huge decrease in comfort level of their trip experience. Passengers consider comfort factor as a new criterion in their choice of public transportation mode. This study conducts an comfort analysis for public transport in the city of Istanbul in Turkey with significant support of İETT, Istanbul Transportation Inc. and City Lines Inc.. Implementation data is obtained from these three institutions and a questionnaire developed for this study helped us define a function to calculate the discomfort level for each mode of public tarnsportation. This function is a piecwise function that takes different values according to the crowd level (for less than 1 or equal or grater than 1). Metrobus line, Yenikapı-Hacıosman metro line and Bağcılar-Kabataş tram line are selected as pilot routes. After literature review and interviews with İETT and Istanbul Transportation Inc., to determine the comfort level of these lines, variables for each type of public transportation used in this study are: crowd level, complaint rates about air conditioning, invehicle cleaniness, information and guidance, seat comfort, in-car smell, the noise and vibration levels in the vehicle, lighting, driver's social behavior, vehicle breakdowns, driving style, and weather conditions. Survey results show that the factors which are effective for trip comfort at each public transportation type are; fulness level of vehicles, air conditioner, in-car smell and invehicle cleaniness. At the same time, the maximum demand rate for public transportation is seen between 7.00-9.00 am and 5.00-8.00 pm. Metrobus, M2 metro and T1 tram line discomfort levels are calculated for two example dates that one of them is a work day and the other one is holiday. Especially on work days at the time which was mentioned above, the discomfort level gives the highest values. Another contribution of the study is development of a function that can be used to predict the number of passengers in a vehicle in a given time and it plays an important role to determinde the crowd level which is the base variable of the discomfort level. A variability occured in discomfort values for which dates are selected before. This value is low or high in different time intervals. The reason of the high values of the discomfort level, is that the piecewise function is defined by exponential terms when the crowd level of the vehicle exceeds the capacity. In conclusion, this study which was conducted for only three types of public transportation can be improved for measuring the comfort level for other cities and comparing them. In addition to this, it can bu used as a multi-criteria mathematical model for mode selection at further research. In many studies for mode selection in the literature includes variables such as transportation cost, travel duration and waiting times. However, because of the increasing crowdedness in nowadays, comfort factor should be added to the transportation mode selection criteria of passengers. In this context, developing a transportation mode selection model including comfort criterias will reflect better the decisions of the passengers.