1. Introduction This dissertation presents the development of a performance-based road maintenance contract model (model). The aforementioned contract model was developed with the aim of reducing the complexity of the performance-based road maintenance contracting process, while at the same time realizing the key advantages that performance-based road maintenance brings, (increasing the quality of performed works, reducing long-term maintenance costs and increasing traffic safety). Also, the developed model can contribute to the reduction of the backlog in the maintenance of road transport infrastructure, which was observed by reviewing the existing literature. All of the above is achieved by the contract model of performance-based road maintenance by combining the broad and rich knowledge of adequate experts in the field of road management and maintenance and by focusing on key performance indicators. The basic assumption of the mentioned model is that each selected performance indicator of a performance-based road maintenance contract further increases the complexity of the process of its creation and contracting, as well as its subsequent implementation, but at the same time each selected performance indicator doesn’t affect the achievement of the key benefits of performance-based road maintenance. A review of the literature revealed that many studies focus on the implementation phase of road maintenance with the application of performance-based contracts and their results, while a smaller number of them focus on the contract creation phase and the contracting process itself. Furthermore, a large number of conducted researches generally deal with the elements that must be covered and included during the creation of a new performance-based road maintenance contract, and a small number of them focus on the selection of performance indicators itself. In conclusion, research dealing with performance indicators and their selection as part of the contracting process is in the vast majority of cases focused on the selection of characteristics of performance indicators and their associated levels, which need to be achieved during contract implementation. Therefore, this research contributes to the area of performance-based road maintenance by developing a conceptually universal contract model from the aspect of selecting the performance indicators themselves and their adequate number. The developed model can be applied for performance-based contracting of road maintenance works for regular maintenance of roads and highways, but also for comprehensive maintenance of the mentioned and all other categories of roads, with certain modifications and adjustments and its upgrading. 2. Elaboration of the current condition of the road maintenance in Europe and the Republic of Croatia 2.1. Analysis of the current condition of the road maintenance in European countries By reviewing the literature and all available current data, a tabular presentation of all data for individual countries of the European Union and the rest of Europe on road safety in terms of the number of injured and killed in traffic and the trend of their movement is given. Then, data on the individual and total length of all roads and their traffic load, the type and amounts of financial investments, the production and use of asphalt and asphalt mixtures and the companies that deal with it, as well as data on the computerization of roads and their monitoring and management systems, are presented. Finally, the overall evaluations of the quality of the road transport infrastructure of each country are presented. 2.2. Conclusion of the analysis of the current situation of road maintenance in European countries From all the collected data, as well as the related reviewed literature, a conclusion about the current condition of the road maintenance in the European Union and the rest of Europe was given, from which it is evident that road safety isn’t at a satisfactory level and that the goals set by the European Union until 2020. years related to security fulfilled only by a small number of countries. Also, the trend of investment in the maintenance of road transport infrastructure is variable on average, which means that there is a rise and fall in investment in maintenance, which implies negative consequences for the quality of road transport infrastructure, as well as safety. Also, irregular and inadequate investments in maintenance lead to the appearance of a backlog in the maintenance of road transport infrastructure, or its additional increase in countries where it is already present, with all the negative consequences it brings. As a logical answer to everything shown, performance-based road maintenance, which was presented in the first chapter of this paper, is presented, with all the advantages it brings. All of the above is sufficient motivation for the creation of a contract model of performance-based road maintenance, which will be able to ensure an increase in the quality of the performed works, a reduction of long-term road maintenance costs and an increase in the level of road traffic safety (which is the most important thing) in all conditions. 3. Performance-based road maintenance 3.1. Road maintenance The review of the available literature shows the definitions of the basic terms related to roads, their systematization and the defined division of road maintenance in the world and in the Republic of Croatia. Also, the importance and impact of regular and adequate road maintenance on the economy, safety and traffic costs, the value of road assets, and the mutual relationship and impact of roads on the environment, as well as the impact and relationship of the environment and climate change on road maintenance, are presented. 3.2. Backlog in road maintenance The backlog in road maintenance is a consequence of irregular and inadequate maintenance of roads and other road assets, most often resulting from an insufficient amount of financial resources for maintenance. In the long term, the aforementioned backlog in road maintenance has significantly negative consequences for the safety of roads, as well as the value of their property. With regard to the available data, the condition of the backlog in road maintenance at the world and European level is described, with exact financial amounts for some European countries, and the general reasons for its occurrence in Europe are stated, as well as the influence of performance-based road maintenance models on its reduction. 3.3. Performance-based road maintenance Performance-based road maintenance, in comparison to traditional maintenance based on performed quantities, bases the success and performance of activities on the achieved predefined maintenance parameters. The history of its creation is described and all areas of its application are listed, as well as the basic reasons for its introduction in the field of construction and maintenance of road transport infrastructure. All its advantages and disadvantages are analysed and described, and all necessary assumptions for its successful implementation are described in detail. 4. Performance-based road maintenance contract model 4.1. All-important prerequisites of the maintenance parameter selection process Performance-based road maintenance contract model was developed as part of this research, with the aim of enabling the simplest possible way of selecting adequate maintenance parameters, while considering all essential elements, accompanying risks and all participants in the process of selecting maintenance parameters, as well as the compliance of the selected parameters with the legal framework and road policy. In the research, all the essential prerequisites and elements of the model parameter selection process are listed, and the most important fact is that the development of maintenance parameters must be part of the early phase of contract development and implementation, and their selection should be based on current data on the condition of the road. Also, it is important to emphasize that the parameters and their default goals must not overlap, or in an even worse case, exclude each other. Therefore, when selecting them, it is necessary to answer the questions whether each selected maintenance parameter is: • Specific • Achievable • Results-oriented • Measurable • Timely • In accordance with the policy of the agency that manages the road • Whether the parameter has already been used earlier on that road? • Is it in line with the interests of all participants? • Is it in line with previous maintenance results, or does it require a higher level of execution and achieved quality than before? • Will the parameter and its required level raise the overall maintenance score? • Is the parameter available considering the available financial resources? Each selected parameter must reflect the set goals, enable their achievement, and must be simple and unambiguous, so that its realization, monitoring and control are as simple as possible, and so that the selected parameters have as little influence on the complexity of contract drafting and implementation. The key emphasis when selecting the maintenance parameters must be on the professional knowledge and long-term experience of the persons (experts) participating in the process, which was achieved during the creation of the model as part of this research, in order to avoid possible risks. Possible risks related with the process of selecting maintenance parameters arise from two directions. The first group of risks arises from the maintenance parameters themselves or is directly related to them, while the second group of risks is indirectly related to the maintenance parameters. The causes of both groups of risks primarily lie in two key elements and their lack will certainly activate some of the risks from the two mentioned groups. These are professional staff who have adequate knowledge and experience in selecting valid maintenance parameters for a certain specific performance-based road maintenance contract, who will be able to see everything necessary for their proper selection with their knowledge and experience, and the second is adequate and accurate data on the current condition of the roads. It should be pointed out that the lack of the first essential element, professional and adequate staff, can be replaced by hiring external experts (consultants), who have the necessary knowledge and experience, while the second element, adequate and accurate data, can only be replaced by expertise of the current condition of the road, which will to collect all the necessary and relevant data about the road, which are necessary for the proper selection of maintenance parameters. By providing these two key elements (professional staff and adequate and accurate data), all possible risks related to the process of selecting maintenance parameters can be significantly reduced (minimized). All the mentioned risks from both groups of risks are listed in this research, and guidelines for their complete elimination are given, or the maximum possible mitigation of the impact on the parameter selection process and its final result. Also, as part of the research, the importance and role of all stakeholders in the parameter selection process was elaborated. Stakeholders in the selection of maintenance parameters are all those who have a certain interest in the maintenance, and that is why during the mentioned process care must be taken to ensure that the selection of the required parameters comprehensively satisfies all the necessary functional, technical, ecological, safety, economic and institutional considerations and needs are comprehensively satisfied by the selection of the required parameters, as well as set goals. All stakeholders can be divided into two groups, direct and indirect, among which the most important is the direct group of stakeholders. Direct stakeholders are: • road management agency and consultants, • potential contractors, • users of the road. The aforementioned group of stakeholders is the most important, and the road management agency stands out among them, since it is the stakeholder that makes all the final decisions, considering the interests of all other stakeholders of both groups. All other participants belong to the indirect group of stakeholders, who in some way have an interest in the maintenance process and whose goals, to a greater or lesser extent, need to be met, and whose fulfilment is again the responsibility of the road management agency. Indirect stakeholders are: • the Ministry of Finance and the Ministry of Transport and Infrastructure, • associations for environmental protection, • government representatives and road policy makers, • tourist Board, • health representatives and representatives of rural development, • associations of drivers and road carriers, • other business and non-governmental organizations. Potential contractors, members of the first group of stakeholders, are very important it this process, because they are the balance between possible wishes and set maintenance goals and the possibilities that potential contractors can present with regard to the given financial frameworks. Potential contractors have a dual role in the process of selecting maintenance parameters. Their primary role is to participate in the parameter selection process to get to know all the requirements and wishes that the road management agency will put before them by selecting the parameters, and to clarify all possible ambiguities in their interpretation, and their second role is to present all their options with regard to capacities and the experience they have, with the intention that the agency defines the parameters and set goals that the contractors can achieve. According to the above, in the process of selecting maintenance parameters, the most important role is played by the road management agency, together with its consultants, which ultimately selects all maintenance parameters and states them in the contract, considering all previously mentioned selection elements, as well as the goals of all stakeholders and their priorities. Also, during the process of selecting maintenance parameters, one more important element should be considered: compliance of the selected parameters with the laws and valid technical and other regulations of the country where the contract is formed. Therefore, when choosing the parameters, it is necessary to study the legal regulations, technical standards and other acts where the minimum criteria for certain categories of roads are stated, and it is necessary to harmonize the parameters with this, at the same time taking care that the selection of individual maintenance parameters doesn’t duplicate certain conditions and requirements for road maintenance, which have already been previously defined by the mentioned legal and technical framework and which can be simply put in the general conditions of the maintenance contract. This will avoid the negative effect of a large number of unnecessary maintenance parameters on increasing the complexity of the contracting process and its subsequent implementation, and at the same time will condition the execution of all activities in accordance with the entire applicable legal framework and technical regulations. In the end, the process of selecting maintenance parameters, in addition to the aforementioned compliance with the applicable legal framework and all technical regulations, must also be aligned with the goals of the national road policy. There are several reasons for this, and among the most important are the fact that states implement the main goals of road transport systems at the highest level with their road policies, which means that they meet the needs and goals (such as that of the European Commission on reducing the number of road traffic fatalities by 50% until 2030), or they want to achieve certain savings in road management and maintenance costs at the level of all road systems in their territory. When the relevant ministries define all the goals that they want to achieve by introducing performance-based road maintenance, it is important to determine and define all maintenance parameters so that they meet the previously set goals, so that the road management agencies receive all the support for the implementation and development of road maintenance using this model. as well as the necessary financial resources for their realization. During the selection of parameters, it is necessary to take care that the selected goals aren’t unnecessarily set too high in relation to expectations, since these can affect the increase in the complexity of the contracts and even more the increase in the total costs of their implementation. The only aspect in which the given goals must not have the restrictions is road safety. And finally, it is necessary that the road management agency, during the selection of maintenance parameters, takes care of the mutual alignment of all its goals with the goals of the state road policy, which means that the goals are not mutually exclusive. 4.2. Establishing an expert team for the process of selecting maintenance parameters Given the fact that the process of selecting maintenance parameters for the contract model of performance-based road maintenance is a fundamental and key step in the formation of the specified type of road maintenance contract, and on which its success largely depends, it needs to be approached with the utmost care and is important for its implementation provide all the necessary elements, and the most important element is the knowledge and experience of experts who select the specified parameters and form a contract model (a maintenance contract). For the purposes of this research, an expert team was formed, which consisted of 7 experts in the field of road management and maintenance, and they had to meet specific conditions. Also, the procedure for selecting the total number of necessary maintenance parameters, as well as the number of their groups, is described, based on all the analysed data of similar existing performance-based road maintenance contracts, as well as the existing guidelines for contracting the relevant contracts issued by the World Bank, considering all the previously mentioned essential elements of the process of selecting maintenance parameters. The aforementioned team was formed with the aim of expertly selecting groups of parameters, maintenance parameters belonging to them and their total number, in accordance with the latest scientific achievements and research, the latest available examples of contracts and guidelines for contracting performance-based road maintenance contracts, the current legal framework of the Republic of Croatia, as well as all technical conditions and regulations related to the road management and maintenance. 4.3. The process and result of the maintenance parameter selection process Once the most important condition for starting the process of selecting maintenance parameters has been implemented and the expert team that will fully implement the process has been successfully formed, it can begin. The first step of the process is the selection of the total number of groups of maintenance parameters, as well as the total number of parameters within the specified contractual model, followed by the definition of the goals to be achieved by the specified selection of parameters in the step 2. In the step 3, the selection of individual maintenance parameters within each individual group is carried out, which meet the previously defined goals that each group of maintenance parameters should meet. After all potential maintenance parameters within each group of parameters have been selected, and the achievement of which can achieve the given maintenance goals, in the step 4 each parameter is assigned an absolute value based on the opinion of the expert team, regarding the influence of the contractor on its achievement, as and the number of stakeholders who have an interest in achieving the goal of the parameter. In step 5, the previously assigned absolute values of each parameter are scored and their ranking is performed regarding the total value. After the total point value has been calculated for each parameter and they have been ranked according to it, the expert team, based on experience and knowledge in the field of road management and maintenance, performs in the step 6 the final selection of parameters that will be included in the performance-based road maintenance contract. The selection along with the total obtained point value of each parameter is made based on the assessment of the impact of the selected parameter on the achievement of the set maintenance goals of the specified group of parameters, as well as their mutual synergistic impact on them. At the same time, the expert team must take care of all the previously described essential elements of the selection of maintenance parameters, starting from the mutual compatibility of the selected maintenance parameters, the existing legal framework and the goals of all stakeholders and road policy. In the continuation of the selection process, all previously described steps are repeated for each of the 5 groups of maintenance parameters, which gives the result of the selection process (36 selected maintenance parameters). 4.4. Verification of the impact of selected groups and their associated maintenance parameters on the key benefits of performance-based road maintenance In the aforementioned part of the work, the results obtained from the previously conducted selection process (selected groups and maintenance parameters belonging to them) are checked from the aspect of their influence on the achievement of the efficiency and effectiveness of road maintenance using a contract model, which contains all the previously selected maintenance parameters, as well as their influence on the achievement of the key set goals that are to be achieved by maintaining the road with the application of that contractual model. Also, for each group and its associated parameters, an analysis of their influence on the realization of key benefits brought by performance-based road maintenance is carried out. The analysis is carried out based on the joint opinion of all members of the expert team, considering all the principles of performance-based road maintenance, such as not limiting the contractor's freedom in choosing technology, focusing on the result, maintenance goal etc. 5. Validation The validation of the research was carried out in two parts. The first part was carried out by interviewing and surveying experts in the field of road management and maintenance, more precisely persons who work as managers of road construction and maintenance projects, persons responsible for the implementation of expert supervision and design of road construction and maintenance works, or as representatives of investors within road management agencies. In the research, the minimum professional competences that each of the respondents had to satisfy to be classified as an adequate expert were specified and defined, and a total of 71 of them fulfil this and participated in the validation process, of which 25 are employed in road management companies, 25 in companies for design and professional supervision, and the remaining 21 respondents in a company for the execution of works. The validation process by surveying the respondents consisted of two parts: in the first part, the research was explained to each respondent, and in the second part, the respondents had to answer the questions. The questionnaire consisted of 49 questions divided into 5 groups. The questions were designed so that from the answers of all respondents, their opinion on each part of the conducted research can be clearly determined, which means that from the received answers it can be clearly seen whether the research hypothesis is confirmed or rejected. The received answers overwhelmingly confirmed the hypothesis, as well as the fact that the objectives of the research were achieved. The answers of most surveyed respondents are very similar and show a positive attitude towards the conducted research, while suggestions and criticisms mainly refer to elements that are normally assumed by such maintenance contracts (mostly found in general terms and conditions), or to the need to secure adequate financial resources, which has been repeatedly emphasized as a necessary condition. The second part of the research validation refers to the implementation of interviews with specifically competent experts in the field of road maintenance and contracting works, which means experts who participate in decision-making processes and the creation of road management and maintenance policies and are employed in institutions responsible for road management and maintenance, or in institutions responsible for creating road policy and valid laws and regulations. Also, the research specified and defined the minimum professional competencies that each respondent had to satisfy to be classified as an adequate expert, and 3 of them met the same and participated in the validation process through interviews. Of these, two are employed in key management positions of a road management company, and the third expert is employed in an institution responsible for creating road policy and applicable laws and regulations. During the interview, each of the interviewees was asked 9 questions divided into 3 parts. The questions were formulated in such a way as to obtain very specific answers related to the necessary prerequisites for the implementation of performance-based road maintenance, the appearance of a backlog in the maintenance of road transport infrastructure, and possible solutions in the form of a related contractual model, as well as to obtain direct and clear answers as to whether the research hypothesis is confirmed or rejected. All answers confirmed the set hypothesis, as well as the fact that the objectives of the research were achieved, and additionally, all interviewed respondents confirm and emphasize the importance of knowledge and professional staff, as well as ensuring an adequate financial framework for the successful implementation performance-based road maintenance model.