publications

Optimizing Fire Station Locations for the Istanbul Metropolitan Municipality

Emel Aktas, Ozay Ozaydin, Burcin Bozkaya, Fusun Ulengin, Sule Onsel

(2013) Interfaces, Volume 43, No 3, Pages 240-255

http://dx.doi.org/10.1287/inte.1120.0671

The Istanbul Metropolitan Municipality (IMM) seeks to determine locations for additional fire stations to build in Istanbul; its objective is to make residences and historic sites reachable by emergency vehicles within five minutes of a fire station’s receipt of a service request. In this paper, we discuss our development of a mathematical model to aid IMM in determining these locations by using data retrieved from its fire incident records. We use a geographic information system to implement the model on Istanbul’s road network, and solve two location models—set-covering and maximal-covering—as what-if scenarios. We discuss 10 scenarios, including the situation that existed when we initiated the project and the scenario that IMM implemented. The scenario implemented increases the city’s fire station coverage from 58.6 percent to 85.9 percent, based on a five-minute response time, with an implementation plan that spans three years.

Are road transportation investments in line with demand projections? A gravity-based analysis for Turkey

Füsun Ülengin, Ozay Ozaydın, Burç Ülengin, Andreas Kopp, Sule Onsel, Özgür Kabak, Emel Aktaş

(2013) Transport Policy, Volume 29, Pages 227-235

http://dx.doi.org/10.1016/j.tranpol.2013.07.002

In this research, an integrated gravity-based model was built, and a scenario analysis was conducted to project the demand levels for routes related to the highway projects suggested in TINA-Turkey. The gravity-based model was used to perform a disaggregated analysis to estimate the demand levels that will occur on the routes which are planned to be improved in specific regions of Turkey from now until 2020. During the scenario development phase for these gravity-based models, the growth rate of Turkey's GDP, as estimated by the World Bank from now until 2017, was used as the baseline scenario. Besides, it is assumed that the gross value added (GVA) of the origin and destination regions of the selected routes will show a pattern similar to GDP growth rates. Based on the estimated GDP values, and the projected GVA growth rates, the demand for each selected route was projected and found that the demand level for some of these road projects is expected to be very low, and hence additional measures would be needed to make these investments worthwhile.

A decision support methodology to enhance the competitiveness of the Turkish automotive industry

Füsun Ülengin, Sule Onsel, Emel Aktas, Ozgur Kabak, Ozay Ozaydin

(2014) European Journal of Operational Research, Volume 234, Pages 789–801

http://dx.doi.org/10.1016/j.ejor.2013.09.044

Three levels of competitiveness affect the success of business enterprises in a globally competitive environment: the competitiveness of the company, the competitiveness of the industry in which the company operates and the competitiveness of the country where the business is located. This study analyses the competitiveness of the automotive industry in association with the national competitiveness perspective using a methodology based on Bayesian Causal Networks. First, we structure the competitiveness problem of the automotive industry through a synthesis of expert knowledge in the light of the World Economic Forum’s competitiveness indicators. Second, we model the relationships among the variables identified in the problem structuring stage and analyse these relationships using a Bayesian Causal Network. Third, we develop policy suggestions under various scenarios to enhance the national competitive advantages of the automotive industry. We present an analysis of the Turkish automotive industry as a case study. It is possible to generalise the policy suggestions developed for the case of Turkish automotive industry to the automotive industries in other developing countries where country and industry competitiveness levels are similar to those of Turkey.

Cumulative belief degrees approach for analyzing the competitiveness of the automotive industry

Ozgur Kabak, Füsun Ülengin, Sule Onsel, Ozay Ozaydin, Emel Aktas

(2014) Knowledge-Based Systems, Volume 70, Pages 15-25

http://dx.doi.org/10.1016/j.knosys.2013.09.006

As traditional competition becomes global, businesses fail to take, on their own, the measures that are required to become more competitive. Hence, in a globally competitive environment, national improvement and competitiveness have also become vital. Businesses must utilize and be supported by the international competitiveness of their nations. This study aims to analyze the competitiveness of the automotive industry from a national competitiveness perspective, using a three-stage methodology. For this purpose, a novel cumulative belief degrees (CBD) approach is introduced, to quantify the causal relations among the variables in the system. This methodology is illustrated by the analysis of the Turkish automotive industry for developing suggestions to assist policymakers in their decisions to improve the competitiveness of the industry. Although the findings are country specific, the methodology is applicable to a wider range of industries in developed and developing countries.

Effects of quotas on Turkish foreign trade: A gravity model

Füsun Ülengin, Bora Çekyay, Peral Toktaş Palut, Burç Ülengin, Özgür Kabak, Ozay Ozaydin, Şule Önsel Ekici

(2015) Transport Policy, Volume 38, February 2015, Pages 1-7

https://doi.org/10.1016/j.tranpol.2014.09.006

Turkey's role as a world trade participant has grown in recent years, particularly as the country is capitalizing more on its unique geopolitical position. Given the important trade volume and rooted relations between Turkey and the EU, their trade and economic relations should be paid due attention and steps should be taken to further improve these relations. Turkey is the biggest economy in a Customs Union (CU) with EU but not in EU, along with Andorra, Monaco, and San Marino. When it joined the CU in 1996, Turkey has removed all customs duties and equivalent charges as well as quantitative restrictions. However some EU countries imposes quota limits to the Turkish road transporters that may indirectly restricts the trade between Turkey and the related country. In this study, we investigate the effect of road transport quotas on Turkish foreign trade with EU countries. A gravity model that is estimated with panel data from 18 selected EU countries between 2005 and 2012 is used for this purpose. Furthermore, as one of the leading sectors using road transportation for Turkey's export to EU countries, textile sector is analyzed as a case study. The results indicate that quotas have significant effects on Turkish total exports via road transport as well as the Turkish textile exports to EU countries. The estimated amount of the loss of the exports of Turkey to the selected countries in analyzed time period is 10.6 billion $ in Turkey's total exports via road transport, and 5.65 billion $ in Turkey's total textile exports. Therefore, it can be concluded that the quota limitations are against CU regulations because they do not limit not on the road transportation but also the trade between parties.

Critical Success Factors for the Iron and Steel Industry in Turkey: A Fuzzy DEMATEL Approach

Ozgur Kabak, Fusun Ulengin, Bora Cekyay, Sule Onsel, Ozay Ozaydin

(2016) International Journal of Fuzzy Systems, Volume 18(3), Pages 523–536

https://doi.org/10.1007/s40815-015-0067-7

The attempt to improve the efficiency and competitiveness of an industrial sector is aided by the determination of critical success factors (CSFs) which focus efforts in those areas that really affect the whole industry, thereby conserving limited resources. In this paper, a three-stage methodology is proposed to find CSFs for an industrial sector. The methodology specifies the interrelations between factors that shape the global competitiveness of a country as a whole and those that shape the competitiveness of the particular industry in question. It integrates a Web-based survey, a Delphi-type workshop, and a fuzzy decision making trial and evaluation laboratory model to highlight those CSFs upon which policymakers should especially concentrate in order to increase the competitiveness of a given industry. This methodology is then applied to a case study, identifying the CSFs of the iron and steel industry in Turkey. The results show that the burden of custom procedures, total tax rate, scope and impact of taxation, and solidity of banks are the CSFs for the competitiveness of the Turkish iron and steel industry.

Analysis of the impact of bilateral and transit quotas on Turkey's international trade by road transport: An integrated maximum flow and gravity model approach

Bora Çekyay, Peral Toktas Palut, Ozgur Kabak, Füsun Ülengin, Ozay Ozaydin, Burç Ülengin

(2017) Research in Transportation Economics, Volume 66, Pages 70-77

https://doi.org/10.1016/j.retrec.2017.04.006

We explore whether bilateral and transit quotas applied by EU countries on Turkey have a negative impact on Turkey's international trade by road transport. Therefore, Turkey's exports by road transport to selected European countries are analyzed in a panel-data framework for the period 2005–2014. We estimate the aggregate effect of different quota types on trade between Turkey and European countries by using an approach that integrates the max-flow and gravity models. In the gravity model, for each country, a single value representing the aggregate restricting effect of different quota types is needed. The single values are obtained by solving multiple max-flow problems, where constraining effects of different quota types are modeled as arc capacities. The results of the gravity model suggest a loss in Turkish exports by road transport because of the quotas imposed by other countries. Most of the negative impact results from bilateral quotas rather than from transit quotas, whose effect is rather marginal.

Policy developments for the reduction of climate change impacts by the transportation sector

Füsun Ülengin, Mine Isik, Sule Onsel Ekici, Ozay Ozaydin, Ozgur Kabak, Y.Ilker Topcu

(2018) Transport Policy, Volume 61, Pages 36–50

https://doi.org/10.1016/j.tranpol.2017.09.008

The transportation sector is one of the most significant sources of anthropogenic greenhouse gas emissions. In order to mitigate climate change, it is important to apply effective and immediate policies to reduce the transportation sector's emissions. This study aims to: (1) define the dimensions of the transportation sector, such as its environmental, economic, social, and political elements, and (2) investigate how they relate to climate change, in order to assess potential mitigation scenarios and policies that could reduce the sector's contribution to climate change. First, sector-related variables were specified using expert opinions and a literature survey. Relationships between the variables and the associated intensity values were then identified using document coding, as well as by gathering expert opinions through a workshop. A fuzzy cognitive map analysis was then conducted to investigate the relationships between the variables and the resulting impacts by the transportation sector on climate change. A scenario analysis was also conducted in order to identify the most effective policies in reducing the impacts of transportation on climate change, at both the local and global levels. For the scenario analysis at the global level, projections by the International Energy Agency were analyzed through the model. The local policy suggestions developed by Turkish authorities were also evaluated using scenario analysis.

A multi-commodity network flow and gravity model integration for analyzing impact of road transport quotas on international trade

Bora Çekyay, Ozgür Kabak, Füsun Ülengin, Burç Ulengin, Peral Toktas-Palut, Ozay Ozaydin

(2020) Research in Transportation Economics, Volume 80, 100816

https://doi.org/10.1016/j.retrec.2020.100816

Although EU and Turkey are integrated by Customs Union since 1996, there are still quota limits to Turkish road transport in some European countries. These quotas cause concerns related to increased transportation costs, which will in turn increase the costs of export goods and create important barriers to international trade. In this study, the effects of quotas on Turkish foreign trade with EU countries are investigated using an integrated multi-commodity flow model and a gravity model. The classical multi-commodity network flow model is innovatively used to predict the costs of transportation with and without the transit and bilateral quotas applied by the European countries. As a result, the extra costs originating from the quotas are forecasted. These extra costs are used in a gravity model to analyze their effect on international trade. The gravity model is estimated with panel data related to 17 selected European countries between 2009 and 2015. The results indicate that the costs originating from the quotas have significant effects on Turkish total exports, and exports of food and beverages and the machinery and equipment sectors. The size of the losses in the total export and the selected sectors are also calculated by using a scenario analysis.

A simulation-based approach for improving the largest border crossing between Europe and Turkey

Füsun Ülengin, Bora Cekyay, Mine Isik, Ozay Ozaydin, Ozgür Kabak, Peral Toktas-Palut, Sule Onsel Ekici, Y. Ilker Topcu 

(2021) Transport Policy, Volume 114, Pages 350–363
https://doi.org/10.1016/j.tranpol.2021.10.011

Kapıkule border crossing, connecting Turkey to Bulgaria, is one of the largest customs gates at Europe via road transportation. Although it has a high capacity and large land area, there occurs long delays in the custom services due to inefficient operations resulting with long queues of trucks and long service times. To overcome this problem, in this study we investigated the strategies that could be implemented to increase the efficiency of the Kapıkule border crossing. In-depth interviews were conducted with the Kapıkule customs gate authorities to determine the process flows. The current situation at the gate was analysed using discrete event simulation. Furthermore, several improvement scenarios were tested to identify those that will have the highest impact on reducing the queues and delays at the border. As a result, specific suggestions were delivered for the import and export processes. According to the results, Turkey's export to European countries by road is expected to increase by at least 5% by the suggested improvements made at the Kapıkule Border.