EKONOMSKA ANALIZA POJAČANOG ODRŽAVANJA DRŽAVNOG PUTA IB21, DEONICA IRIG - RUMA ECONOMIC ANALYSES OF HEAVY MAINTENANCE (UPGRADING) OF STATE ROAD IB21, SECTION IRIG-RUMA

Putna infrastruktura je meću najvrednijim dobrima jednog društva i indikator je razvoja nacionalne ekonomije. Ulaganja u održavanje, rekonstrukciju i modernizaciju puteva u svetu, u poslednjih dvadesetak godina, veća su nego u izgradnju novih puteva. Upravljanje održavanjem putne mreže predstavlja proces donošenja odluka o investicijama, u kojem je veoma znađajno razrešiti brojna tehniđka i ekonomska pitanja i obezbediti što više objektivnih tehniđkih i ekonomskih informacija za konađno donošenje odluke. Planiranje održavanja putne mreže jedan je od osnovnih zadataka za svakog upravljađa putnom mrežom [1]. Za potrebe efikasnog planiranja i upravljanja održavanjem putne mreže neophodno je raspolagati ažurnom informacionom osnovom i odgovarajućim modelom za donošenje odluka [2]. Model za analizu investicija u razvoj i upravljanje putevima HDM-4 (The Highway Development and Management Model) predstavlja kompleksan softverski alat za tehniđko-ekonomsku ocenu


INTRODUCTION
Road infrastructure is one of the most valuable assets of a society and a good indicator of development of national economy.Over the past two decades, worldwide investments in the maintenance, reconstruction and modernization of roads have been significantly higher than the investments made in the construction of new roads.The management of the road network presents the process of decision making in investments, where it is very important to solve numerous technical and economic problems and provide as much objective technical and economic information as possible for final decision making.Planning the maintenance of the road network is one of the basic tasks for each road network manager [1].
Cela analizirana deonica podeljena je na homogene poteze prema [4,5]:  saobraćajnom opterećenju;  dominantnoj geometriji puta;  utvrđenoj strukturi kolovozne konstrukcije;  utvrđenom stanju kolovozne konstrukcije;  predviđenim radovima na pojačanom održavanju.Razlika u troškovima i koristima između varijante "projektno rešenje radova na pojačanom održavanju" u skladu sa Glavnim projektom pojačanog održavanja i varijante "minimum radova na održavanju" izračunata je za svaku godinu posebno za period eksploatacije puta od deset godina.Neto sadašnja vrednost (NSV) i interna stopa rentabiliteta (ISR) za projekat izračunate su, kao i odnos neto sadašnje vrednosti prema investicionim Model) for the analysis of investments in the development and management of roads is a complex software tool for the technical and economic evaluation of road projects, and for analyzing investments in the existing road network.The model is widely accepted by the International Financial Institutions (IFIs).The HDM-4 model can be used to: conduct strategic analyses at the level of the road network (or part of the road network), program road maintenance and improvement activities on the road network, and make analyses at the project level.The strategic and programme analyses of the road network are carried out on the basis of adequate and updated road network information base (RDB -Road Data Base), while the project-level analysis requires preparation of appropriate design and technical documentation (Final/Detailed Design).After the conduct of strategic and/or programme analyses of the road network, appropriate design and technical documentation should be prepared for selected priority sections, in accordance with the legal procedure [3].
Road Rehabilitation and Safety Project (RRSP) is a project of support of international financing institutions (World Bank, European Investment Bank and European Bank for Reconstruction and Development) to the Government of the Republic of Serbia in implementation of the National State Road Network Rehabilitation Program.The section of the state road IB21, Irig-Ruma, in the total length of 15,580 km is part of the RRSP project and is planned for realization in 2018.
This paper presents a methodological procedure for the preparation of economic analysis and assessment of investments for the periodic maintenance of roads with example of the state road IB 21, section Irig-Ruma.

Technical -economic analysis of the design
Technical -economic analysis of the justification for heavy maintenance of the state road of the road IB-21 on the section: Irig 2 -Ruma 1 in the total length of 15,580 km was carried out using the HDM-4 model (Highway Development Management Model, v2.08) in the project analysis.
Upon the general analysis of the entire considered section, it was divided into homogeneous subsections.Each selected homogeneous subsection is specifically processed and analyzed at the project level.The whole analyzed section is divided into homogeneous moves according to [4,5]:  traffic load,  dominant road geometry,  determined structure of the pavement structure,  determined condition of the pavement structure, and  planned works on heavy maintenance The difference in costs and benefits between the variant ''design solution for heavy maintenance'' in accordance with the Main design for heavy maintenance and the ''minimum works on maintenance'' variant is calculated for each year, in particular for the 10-year period of exploitation.Net present value (NPV) and the internal rate of return (IRR) for the design are calculated, as well as the ratio of net present value and investment (kapitalnim) troškovima radova (NSV/CAP).
The sensitivity analysis of the results was made to illustrate the importance of changes in the cost of carrying out works on heavy road maintenance as well as changes in forecasted traffic flows.The economic analysis is based on the following assumptions:  the starting year of the analysis is 2017. analysis (exploitation) period is 1+10=11,  the initial period of works on heavy maintenance of the road section is during 2017.(100%),  the starting year for road exploitation is 2018.
 the costs of works on heavy maintenance of the state road IB-21 on the section: Irig 2 -Ruma 1 (Motorway) are taken from the Main design of heavy maintenance of the state road of the road IB-21 on the section: Irig 2 -Ruma 1 (Motorway), March/July 2017 [6],  discount rate is 8%,  the ratio of the economic towards the financial value of costs is 0.80,  exogenous costs and benefits from social aspects are excluded from the economic analysis of the design due to the lack of data and detailed studies,  exogenous costs and benefits of the impact of the road on the environment are excluded from the economic analysis of the design due to the lack of data and detailed studies,  salvage value for road improvement is 10%.The period of 1+10 years implies one year for the execution of works (period in which the enhanced maintenance works are carried out), while the period of 10 years is the period of exploitation of the road after the completion of the works and in which full benefits are achieved in the form of reduced operating costs of vehicles and reduced travel time.

Calibration model HDM-4 for application in the local conditions
For the needs of adequate application of the HDM-4 model, the HDM-4 model was adapted for use in local conditions that are characteristic for the Republic of Serbia.
In the elaboration of the economic analysis and calibration of the HDM-4 model for application in the local conditions, recommendations and results of the research on the road network of the Republic of Serbia, implemented for the needs of the realization of the project of the database of roads, were used [7][8][9].
tions on the conditions that must be met by road structures and other elements of public roads from safety aspects" [10] which is in the further text called Regulations on road design.The section belongs to Vojvodina region and is situated in Srem administrative district, and stretches in Ruma and Irig municipalities.The road section runs along a plain and hilly terrain with an altitude of about ~150 m a.s.l. on average.Main roadway is 15.580 km long and it stretches from km 26+280 to km 42+260.
According to the new reference system of the national road network of the Republic of Serbia [11], the considered section for heavy maintenance includes the following primary traffic sections of the reference system shown in Table 1.

Geometrical elements of horizontal and vertical alignment
The overall design speed of the section is 80 km/h.The following table shows the boundary elements of the plan and profile for the given section which are show in Table 2.

Najmanja dužina pravca (m)
The shortest straight section (m) 120 ( 240  * The design speed on the whole section is 80 km/h, except for the section from km 26 + 880 to km 26 + 960 where the path is in a vertical curve that fails to satisfy the design speed of 80 km/h.For this stretch, the data in Table 2 for the design speed of 60 km / h is displayed.Given that this is an enhanced maintenance project and a relatively short subsection (l = 80m), the same data insignificantly affects the interventions and the costs of the works.
Very high variation coefficient is the result of long straight lines and horizontal curves with large radii and small deflection angles.

Adopted characteristics of the section by homogenous sub-sections
In Table 4 shows the characteristics of the existing section Irig -Ruma which are presented per homogenous subsections: Tabela 4. Geometrijske karakteristike deonice po homogenim potezima [9] Table 4. Geometric characteristics of the section by homogeneous sub-sections [9] R.b. Ord.

Existing Pavement Structure
Composition of pavement was analyzed based on the historical data from 2004 as well as based on additional test pits drilling done in June 2016.Tabela 5. Struktura kolovozne konstrukcije po homogenim potezima [9] Table 5. Pavement structure by homogeneous sub-sections [9] Debljine asfaltnih slojeva Thickness of asphalt layers(cm) Determination of geo-mechanical properties included the following:  determination of material particle size distribution,  determination of consistency limits of the material,  determination of bulk density and natural moisture,  Proctor's test.

Pavement dimensioning
Methodological approach of the necessary reinforcement analysis The analysis of the existing pavement bearing capacity and the calculation of required overlay in this design is based on -REVISED AASHTO OVERLAY DESIGN PROCEDURE (1993) [12].
The analysis is comprised of defining existing pavement bearing capacity and defining required bearing capacity for future operational conditions.The required overlay is calculated according to the following equation: (1)
Na osnovu dijagrama kumulativnih razlika dobijeni su homogeni potezi.U sledećoj tabeli date su srednje vrednosti za IRI i 85-procentne vrednosti po homogenim potezima, kao i ocena stanja prema navedenom kriterijumu: For the new layer of bituminous materials, the coefficient of material substitution apoj = 0.40 was adopted.For the existing pavement structure, the following coefficients of material substitution were used:  asphalt layers aasf = 0.35  cement stabilized stone aggregate, acs = 0.20  unbound stone aggregate layer adk = 0.10 Based on the established condition of the pavement structure (type and extent of damage) and on the basis of the ETL (Equivalent Traffic Load), appropriate measures have been proposed for the rehabilitation of the pavement structure.

Pavement longitudinal roughness
A performance of the pavement longitudinal roughness -International Roughness Index (IRI) represents a measure of driving comfort and is determined by a continual measurement made at certain distances [13].Measurement is performed by a profilometer -laser beam installed on front part of a vehicle moving at speed higher than 40 km/h (fully in compliance with the standard SRPS EN 13036-6:2012).
Based on Cumulative difference chart homogeneous sections have been identified.Average values of IRI and 85% values by homogeneous sections and condition assessment by stated criteria are shown in the following table : Tabela 7. Ocena stanja kolovozne konstrukcije po homogenim potezima -IRI [9] Table 7. Assessment of the pavement condition by homogeneous subsections -IRI [  Metodom kumulativnih razlika (AASHTO) definisani su homogeni potezi prema defleksijama površine kolovoza d0.U narednoj tabeli prikazane su izmerene defleksije po homogenim potezima: 1200 mm, 1500 mm and 1800 mm.Measurement was done in a wheel trace at every 100 m per lane, i.e. intermittently at every 50 m.
Total of 313 tests was done.Deflections were adjusted by a correction factor 0.865 in accordance with the Protocol 3 (CROW Report D11-07) -Short Term Repeatability Verification and Protocol 10 (CROW Report D11-07) -Falling Weight Deflectometer correlation trial.

TRAFFIC ANALYSIS
The information base for the preparation of this report is the following data on traffic load:  data specified in the project task for the preparation of the Main Project for Improved Maintenance of the State Road IB 21, section: Irig 2 -Ruma 1 (Highway), L = 15,460 km;  data collected by control counting of traffic;  the data is downloaded from the website of PE Roads of Serbia;  data from the traffic counter number 2072 taken from PE Roads of Serbia.

Traffic load projection
Traffic load is necessary for the road design process and refers to the time sections in the future, so the terms of reference and the associated methodologies define the planning period according to the functional type of a road and the type and scope of planned construction interventions of 10 years.A further analysis will show the traffic load for a ten-year planning period.
Relevant traffic load on the section ID 02105 during the planned period in the base year of 2016 is shown in Table 10.
Relevant traffic load on sections ID 02106, ID 02107 and ID 02108 during the planned period within the base year of 2016 is shown in Table 11.

Traffic accidents analysis
For the needs of the economic analysis development, the following input data were adopted for analyzing the costs of traffic accidents on the section of the state road IB-21, Irig  average rate of traffic accidents with mat.damage per 10 8 vehicles-km is: 21.21  the average number of traffic accidents is: 17  the average number of traffic accidents per km is: 1.09 The average costs of traffic accidents are presented in the following Table 12.
The total costs of traffic accidents (undiscounted) in the analyzed period (2017-2027) were estimated at 8,335,000 €.The costs of traffic accidents are not included in the Economic Analysis.

Routine maintenance
Within the framework of defining the "scenarios" of the basic variants for comparison ("minimum work on carriageway maintenance"), works on regular road maintenance are included.These works in the HDM-4 model do not affect the model of the change in the condition of the carriageway during the time, but they only burden economic analysis with the additional costs of the arrangement of the roadside area ("miscellaneous operations") [16].Routine maintenance works generally include the following works [17]:  reviewing and monitoring the condition of roads and structures;  partly repairing and renewing the road bed;  cleaning the carriageway within the boundaries of the roadside area, or the protection zone where the field is erosive;  protection of slopes of the embankments, cuts and side cuts; The abovementioned costs of the works include all the expenses of the enhanced maintenance works that are foreseen in the Main Design of the enhanced maintenance:  the building parts,  geodetic part,  objects,  traffic signalization and equipment,  regulation of traffic during works,  drainage and  lighting.Works on heavy road maintenance are planned during the year 2017 (100%).

Sensitivity Analyses
Analysis of data sensitivity is conducted for following cases:  Traffic volume reduction for -20%,  Increase of total costs of the works for +20%,  Traffic volume reduction for -20% with increase of total costs of the works for +20%.

Air pollution costs analysis
Pollution costs refer to the energy usage of road traffic.The following emissions of pollutants are calculate based on energy usage: CO, NOx, CO2, SOx.Speed of the vehicle and length of the road connection determines fuel consumption (gasoline or diesel), based on the type of the vehicle.
Calculation of vehicle emission and air pollution costs are calculated with HDM-4 model.Because of the nature of the design (heavy maintenance) there is no significant changes in vehicle movement regime so savings are relatively small and estimated on 28,035 € (undiscounted value) during analysis period (2017.-2027).

CONCLUSIONS AND RECOMMENDATIONS
 Economic analysis is based on the model HDM-4.This model calculates discounted flows of pure benefits during the analyzed period.Economic analysis is conducted for the period of exploitation of 10 years.Total period of analysis is 1+10=11 years (2017-2027 year)  Works on heavy maintenance will be executed during the year 2017.(100%)  Exploitation begins in 2018. Total value of investment in the first year of analysis is estimated on 5,175,240 €, or 332,172 €/km (financial value).
 The results of economic analysis for works on heavy maintenance of section in subject expressed through Internal Rate of Return (IRR=31.5%) and Net Present Value (NPV=7.94mil.€) show that investment for works on heavy maintenance are justified.
 The results of sensitivity analysis show that designed solution is acceptable, especially when social aspect requirements were not considered as it was the case in this analysis.vidu da u okviru ove analize nisu razmatrane egzogene koristi iz socijalnog aspekta.
Autori zahvaljuju na trudu i razumevanju svim nadležnima koji su odobrili rad i upotrebu podataka  Unfortunately, due to the very nature of the project, primarily referring to road maintenance (heavy maintenance), there is no reduction in the number of traffic accidents, but it increases in proportion to the increase of AADT.The total cost of traffic accidents (undiscounted) in the analyzed period (2017-2027) was estimated at 8,335,000 €.The cost of traffic accidents is excluded from the economic analysis.
 Savings generated through reduced air pollution are relatively small and estimated at € 28,034 during the analysis period (2017-2027).These benefits are excluded from economic analysis.
 Based on the results it can be concluded that investment in proposed measures for heavy maintenance on road section of the state road IB-21, Irig 2 -Ruma 1 in total length of 15.580 km is economically justified.

Figure 1
Figure 1 shows a change of pavement surface condition depending on the design solution.