RELIABILITY OF LOGISTICS CHAINS IN FOREIGN TRADE OPERATIONS

1* Department of International Transportation and Customs Control, National Transport University, Mykhaila OmelianovychaPavlenka str., 1, 01010, Kyiv, Ukraine, Contact tel.: +38 (068) 811 61 21, E-mail: Natali.Luzhanska@gmail.com, ORCID 0000-0002-1271-8728 2* Department of International Transportation and Customs Control, National Transport University, Mykhaila OmelianovychaPavlenka str., 1, 01010, Kyiv, Ukraine, Contact tel.: +38 (068) 123 87 33, E-mail: i.h.lebed@gmail.com, ORCID 0000-0003-0707-4179 3* Department «Road Transport and Traffic Management», Belarusian State University of Transport, Kirova str., 34, 246653, Gomel, Belarus, Contact tel.: +37 (529) 620-71-45, E-mail: ira.kravchenya@gmail.com, ORCID 0000-0002-2670-639X 4* Department of Transport Units, Dnipro National University of Railway Transport named after Academician V. Lazaryan, Lazaryan str., 2, 49010, Dnipro, Ukraine, Contact tel.: +38 (097) 727-58-00, E-mail: uamazurenko@gmail.com, ORCID 0000-0001-5591-1790


Introduction and problem statement
The process of logistics chain planning significantly affects the efficiency of the international goods delivery. It is determined by consumers of customs and logistics services based on its cost, shipping time, quality and reliability [1]. Given the strong competition among actors in the transport service market, the issues related to the assessment of the reliability of goods delivery organization and the completion of all related procedures are becoming especially relevant.
Typically, it is difficult for cargo owners inexperienced in dealing with actors in the transport service market to choose partner organizations that are able to offer a high level of service and perform servicing at a reasonable price respecting the delivery date. In addition, each company provides a different range of services, sets the cost of service depending mostly on their expenditures on service provision, forms of ownership, tax burden and other costs incurred in providing services to individual customers and production activities of the enterprise as a whole. Therefore, when forming a logistics chain, each customer makes a choice of a transport market entity based on the available resources of their own company as well as the need for cooperation with other relevant companies [2].
The current practice of organizing foreign trade operations in Ukraine is characterized by the use of four types of the most common logistics chains, which provide for the division of responsibilities between the organizations that are a part of their structure as links. The operation of each link involves the direct performance of their direct responsibilities, as well as interaction with other links in a logistics chain related to the organization of document management and other operations aimed at organizing the movement of material flow [3]. This process requires the interaction of enterprises to coordinate actions, compliance with work regulations and quality performance of their direct responsibilities. Accordingly, depending on the number of enterprises included in the logistics chain, the duration of preparatory and organizational work can change. Since each of the involved units has its own software used for paperwork that can be different in its structure and content, the distribution of functional responsibilities between the structural units of an enterprise involved in service provision is performed in accordance with the charter of the enterprise and is not changed depending on the requirements of the customer or in order to establish interaction with other parts of the logistics chain.
The key actors in the transport service market that are involved in logistics chain formation are freight forwarding companies (without their own fleet), customs brokers, transport companies, warehousing organizations and freight customs complexes [1,4]. To date, there are four most common types of logistics chains involved in export-import operations. Each of them is characterized by its own organizational structure and division of functional responsibilities, has its advantages and disadvantages and, nevertheless, can be used by any exporter.
We take into account that logistics chain links in international road transportation are consignors (C-R); consignees (C-E); freight forwarders without their own fleet of vehicles (F); shipping carriers that provide vehicles only and no organizational support (C);customs brokerage companies (CBCs); freight forwarding companies that are able to provide the customer with organizational support as well as a vehicle that meets the shipment requirements(FFCs); warehouse complexes (CFs); freight customs complexes that can be involved as customs infrastructure facilities for the completion of customs formalities for the export of goods at a customs checkpoint operating in its territory, or as an organization providing complex customs and logistics support for foreign trade operations (CCCs); checkpoints (CPs); customs agencies in a country of consignment (СAs); logistics centers in a country of consignment (LC) [5].
Type 1 logistics chain ( Fig. 1) is the most complex in its structure and involves close cooperation of all the logistics chain links, as each of them fulfills its part of the obligations to the customer within its own organization requiring coordination and exchange of information.
According to type 2 logistics chain (Fig. 2), the activity of freight forwarding companies involves organizational support to ensure foreign trade operations and the provision of vehicles.
Type 3 logistics chain ( Fig. 3) is characterized by the involvement of a customs clearance specialist employed by a freight forwarding company. This greatly simplifies and improves transportation and customs paperwork.
Type 4 logistics chain (Fig. 4) is quite new for Ukrainian customs and logistics service users. Because most domestic companies are not able to provide a full range of services due to limited financial resources and logistics. However, over time, companies have entered the market, which in terms of their staffing and infrastructure can create all the favorable conditions for complex service. A significant advantage of this logistics chain is the ability to complete extraordinary customs formalities for export at a checkpoint located in the territory of a freight customs complex.  In general, each of the studied logistics chains is quite effectively used by domestic entrepreneurs, thus contributing to the growth of demand for various types of services and boosting business activities of enterprises of various forms of ownership and specialization.
The decision on the choice of a particular logistics chain type used for the foreign trade operation is made by the customs and logistics service user and depends solely on their needs and general requirements for the shipment of goods [6].
To assess the effectiveness of the use of logistics chains, we conduct a survey of 483 customers with significant experience in export operations. Following its results, most respondents note that at the beginning of their operation they conducted foreign trade operations using mainly type 1 logistics chain; however, they increasingly prefer complex services (type 3 and 4 logistics chain) and declare a fairly high level of satisfaction with this type of operation. Figure 5 shows a histogram of the distribution of the number of customers using different logistics chain types. In this case, each of the customers justifies their choice by one of the criteria including time, cost, quality and reliability. The respondents` assessments according to these criteria are the following. According to the survey results, most customers choosing type 1 logistics chain are guided by the cost criterion. In terms of this criterion, it is possible to individually agree on a lower cost of service with each entity in the transport service market. But entrepreneurs are aware of the risk of additional time expenditures involved in the search for these organizations and negotiations.
Type 2 logistics chain is chosen by customers who are guided by the time criterion. For the most part, significant time is spent searching for a carrier with the fleet of the required type and capacity, so the possibility of organizing freight forwarding services and the availability of vehicles owned by the company makes it possible to speed up the delivery process.
According to the quality criterion, the vast majority favor type 3 logistics chain. The ability to provide a package of freight forwarding and customs brokerage services is considered quite valuable among customers.
Consequently, by the reliability criterion, customers seek to minimize the number of transport service market entities involved in the logistics chain. Customers choose type 4 logistics chain because only within the framework of complex customs and logistics services it is possible to ensure a high degree of efficiency of goods delivery and the concentration of responsibility for the process within the activities of one legal entity. Figure 6 shows the distribution of the number of customs and logistics service users according to the criteria underlying the choice of certain logistics chain types. The analysis of the survey results shows that the issues of quality and reliability of delivery are becoming increasingly important among customs and logistics service users, which will ensure a high level of confidence that contractors have in domestic exporters and reduce the number of violations of foreign trade contracts due to delays, loss or damage to the goods during transportation or poor preparation of shipping documents.
We evaluate the reliability of the four types of logistics chains based on a simulation model developed in GPSS [7,8] using the method of statistical testing or the Monte Carlo method. The essence of the method of statistical testing is to make playouts using a procedure generating a random result [9,10]. With the help of a playout we get one implementation. When playouts are repeated, statistical material is accumulated and then processed using the method of statistical testing. The GPSS simulation system uses a pseudo-random number sensor as a random element, which uses Lehmer's multiplicative congruent algorithm to simulate random processes [11].
The reliability of the logistics chain lies in the timely delivery of goods to the consignee in full and ensuring appropriate quality.
When assessing the reliability of the logistics chain, the following features can be identified [12][13][14]: 1. The logistics chain has a rather complex structure. Cooperation of legal entities providing different types of services and having their own requirements for document management and information support need to be quickly adapted to interaction with other actors in the transport service market in order to organize actions in the interests of the customer.
2. There is not always a clear functional relationship between the processes that take place within the logistics chain, and in most cases this relationship is probabilistic.
3. Occurrence of some processes in a logistic chain or deviation of current processes from the set characteristics has probabilistic character and is defined by the influence of the external environment.
In such conditions, it is difficult to trace all the reasons that may lead to a service refusal or a failure in the logistics chain as well as to assess its reliability based on analytical methods used for the analysis of technical systems.
In this case, to assess the reliability of the logistics chain, it is advisable to use a logistics chain simulation model developed in GPSS [7,15]. With the help of the simulation model, we can determine: -probabilistic indicators of the four logistics chain types, including the probability of timely shipment; -reliability of the logistics chain as a whole and its individual elements (links); -the structure of the four logistics chain types with the specified reliability characteristics under certain constraints that are optimal according to the selected criteria for evaluating efficiency.
Simulation modeling in GPSS, which is a machine implementation of the method of statistical testing or the Monte Carlo method, allows us to solve the problems of not only analysis (evaluation of a logistics chain structure, the impact of changing various parameters), but also synthesis, when it is needed to create a system with specified reliability characteristics and certain constraints that are optimal according to the selected performance evaluation criteria.
Processing of simulation results is carried out by a limited number of implementations of a random process (sampling). The minimum number of tests is determined on condition of obtaining the specified accuracy and reliability.
Based on a supply chain simulation model, we determine the reliability of the four logistics chain types in goods delivery of on Kyiv -Budapest (Hungary), Kyiv -Bordeaux (France), Kyiv -Madrid (Spain) routes.
To ensure the specified accuracy of the assessment of probabilistic characteristics by the method of statistical testing in GPSS, it is required 87,600 hours of the simulated time of the logistics chain simulation model operation [16].
To assess the reliability of logistics chains in the delivery of goods on the route Kyiv -Budapest and with the use of GPSS, we conducted 558 implementations of the simulation model for type 1 logistics chain, 603 type 2 logistics chain model implementations, 685 type 3 logistics chain model implementations, and 1189 implementations of type 4 logistics chain model. The logistics chain performance assessment in shipment on the route Kyiv -Budapest is given in tables 1-4.  To assess the reliability of logistics chains in the delivery of goods on the route Kyiv -Bordeaux and with the use of GPSS, we conducted 327 implementations of the simulation model for type 1 logistics chain, 332 type 2 logistics chain model implementations, 346 type 3 logistics chain model implementations, and 440 implementations of type 4 logistics chain model. The logistics chain performance assessment in shipment on the route Kyiv -Bordeaux is given in tables 5-8.  To assess the reliability of logistics chains in the delivery of goods on the route Kyiv -Madrid and with the use of GPSS, we conducted 273 implementations of the simulation model for type 1 logistics chain, 285 type 2 logistics chain model implementations, 307 type 3 logistics chain model implementations, and 342 implementations of type 4 logistics chain model. The logistics chain performance assessment in shipment on the route Kyiv -Madrid is given in tables 9-12. The reliability of the logistics chain and its links is determined both by assessing the probability of timely execution of individual foreign trade operation procedures, and the process as a whole. In particular, we consider the process of goods delivery on Kyiv -Budapest route. The total shipping time for the various logistics chains significantly differs. And as experts of the enterprises in the field note, these differences are caused by time expenditures on the search for entities in the transport service market, agreeing terms and conditions of cooperation and the cost of service -it takes a considerable amount of time (Fig. 7). Accordingly, we determine the reliability of delivery along the route when customer service is provided utilizing different logistics chains (Fig. 8). According to the obtained findings, we can conclude that in case of complex customs and logistics services, the reliability is the highest and amounts to 0.92, while type 1 logistics chain is characterized by 0.75 reliability To put it into perspective, let us analyze Kyiv -Bordeaux route. In this case, the delivery relying on type 4 logistics chain is reduced by 80 hours as compared to type 1 (Fig. 9). Accordingly, similarly to Kyiv -Budapest route, type 4 logistics chain is characterized by the highest reliability (Fig. 10). Carriers are usually reluctant to take orders for long-haul transportation. This type of transportation is characterized by a significant number of risks associated with the technical condition of the vehicle, the driver`s psychophysical state and the need to take into account many transportation and customs formalities when organizing traffic in transit countries. Nevertheless, for comparison, let's examine the indicators of shipping time and reliability of delivery on Kyiv-Madrid route. Accordingly, shipping time on the first route is 420 hours, and when completing export formalities at the freight customs complex, it equals 330 hours (Fig. 11).
Reliability on this route is much lower as compared to the previous ones according to all the types of logistics chains, but in case of type 4 logistics chain it is the highest (Fig. 12). The reliability of type 1 and 2 logistics chain is characterized by lower figures because to ensure a quite high reliability level of a logistics chain as a whole it is necessary to ensure a sufficiently high reliability level of each of its links. In this case, due to a large transportation distance, there may be difficulties in finding carriers capable of performing transportation on such a route and providing a vehicle.

Conclusions
The conducted research findings indicate the demand for organizing foreign trade operations according to the four most common types of logistics chains. Each of them differs in the number of actors in the transport service market performing various functions to ensure the delivery of goods from the consigner to the consignee in international road transportation. At the same time, customs and logistics service users when choosing intermediary companies increasingly prefer indicators of service quality and reliability to shipping time and cost, which significantly affects the efficiency of foreign economic activity. When assessing shipping time on Kyiv-Budapest, Kyiv-Bordeaux and Kyiv-Madrid routes, there is a clear tendency that the more entities in the transport service market are included in the logistics chain structure, the longer the foreign trade operation takes. Reliability, in turn, also increases as the number of links in the logistics chain decreases.