Description
Introduction
- Background of the Study
Nowadays, highway pavement construction, maintenance and rehabilitation costs are rising dramatically. It is essential for highway agencies to utilize tools and approaches that facilitate proper decision-making by applying economics and operations research such as Life-Cycle Cost Analysis (LCCA) to achieve economically reasonable long-term investments. LCCA is a method based on principles of economic analysis. It improves the estimation of the total long-term economic viability of different investment options (Akakin et al., 2019). This method finds significant application in pavement design and management (Tayabji et al., 2010). A number of agencies employ the LCCA approach to estimate the economic feasibility of pavement designs over the long haul. Thus, it is very important for agencies to realistically evaluate pavement economics in order to provide suitable input to the LCCA.
As a concept, it was in the 1950s that benefit-cost analysis (BCA) was initially applied as a selection factor for various pavement design options. Then in the 1970s, LCCA principles started being implemented in some key projects at the local and national state levels for pavement design and pavement type selection ( AASHTO, 2013).
Considering the mostly inadequate funding under normal circumstances, road authorities are consistently challenged with funding projects due to resource insufficiency (OECD, 2015). Moreover, with the increasing demand for new road infrastructure, the demand for efficient management of old and new roads is on the rise as well, along with safety demands, accessibility and the implementation of advanced traffic management systems for decreasing socio-economic costs by mitigating maintenance-related environmental effects, traffic issues, and losses. Maintenance backlogs nonetheless increase too (OECD, 2015). Road authorities thus emphasize more on better efficiency and lower expenses due to limited funds. Since maintenance expenditures normally comprise half the annual road infrastructure funds, it is very important to prioritize efficiency in road maintenance (FHWA, 2019). Thus, with respect to road objects, life-cycle costs (LCCs) are regarded as having higher priority than simply investments. Hence, road authorities are expected to realize the importance of LCCA and maintain a calculation system (Dam, et al., 2012). LCCs are also deemed to be a restraint in road design selection or the assessment of tenders (Dam, et al., 2012). When calculating LCCs, both road authority costs and costs of socio-economic nature should be taken into account. Road agency (authority) costs comprise expenses for planning, construction, design, maintenance, and rehabilitation. All these costs are usually the government’s responsibility to cover using tax earnings. Socio-economic costs comprise agency costs, user costs (e.g. delay costs, accident costs and vehicle operation costs), and environmental costs (Kosmatka et al, 2013).
- Problem statement
The dramatic increase in traffic volume in built-up areas, such as the Capital Area, road corridor to the port Djibouti and other Federal Trunk Roads of Nigeria results in more and more construction of new roads and modernization of old ones. Therefore, this requires further studies on how road pavement types are selected.
Road Authorities could make more informed and better investment decisions, because pavement type has a significant impact on future cost and service quality. Traffic growth, especially in heavy axle traffic, can cause damage to pavements much quicker than expected, in turn causing more maintenance and thereby increasing agencies and users costs.
Pavement type choice is usually based on traffic level, soil conditions, atmospheric factors and costs. In many cases, the initial construction cost is the main consideration; the future maintenance and rehabilitation costs may sometimes be forgotten.
Life Cycle Cost Analysis (LCCA) is a process that compares the long-term economic worth of competing alternatives and the results could be useful as a decision-supporting tool.
According to the American Association of State Highway and Transportation Officials (AASHTO) Guide for the Design of Pavement Structures, life cycle costs “refer to all costs which are involved in the provision of a pavement during its complete life cycle”. That means that all pavement options are evaluated by taking into account different agencies and users costs.
Agencies costs include initial construction costs as well as future costs of rehabilitation, maintenance and facility operation. User costs are a result of many different issues, for instance increased delay costs, increased vehicle operating costs or charges in accident costs due to future maintenance actions (Yongyuth et al., 2012).
All types of asphalt binding materials used in our country are imported with hard currency and its cost is becoming increasingly high from time to time. On the other hand cement materials have high potential of production in Nigeria and it is hoped that the price will decrease. Asphalt pavement requires heavy maintenance activities starting from early stages of its service life, but
Cement Concrete as an Alternative Pavement Material Over Asphalt Concrete in Arterial Roads of Nigeria; Life Cycle Cost Comparison and Economic Analysis rigid pavements do have long design life time and not required as such maintenances in its early service life. Hence, this study will try to address the problem and show economic advantages of using locally available resource for sustainable pavement construction.
- Aim and objectives
The main aim of the study is to investigate the economic and life cycle cost benefits of concrete over asphalt pavement, that is, to identify the sustainable and economical pavement material in arterial roads of Nigeria by making life cycle cost comparisons and economic analysis of Cement Concrete with Asphalt Concrete pavement materials in selected representative arterial roads of the country.
The specific objectives are:
- To identify the initial cost for both concrete and bituminous pavements.
- To identify the required types of life time maintenances for both concrete and bituminous pavements.
- To identify the various costs related to various maintenances involved in concrete and bituminous pavements.
- To carry out economic evaluation of concrete and bituminous pavements on selected segments of roads in Nigeria for forty years and to determine which pavement type is more economical and sustainable.
- To draw conclusions and forward recommendations based on the findings of the study.
- Scope and limitations
The primary objectives of road construction project planning are to optimize quality, cost and time. In Nigeria, this construction industry and its management is at an infant stage, fulfilling these requirements is difficult and challenging. This research work therefore, focuses on one of the basic requirements i.e. cost. Hence, the scope of the study is restricted to the identification of Cement Concrete as an Alternative Pavement Material Over Asphalt Concrete in Arterial Roads of Nigeria ; Life Cycle Cost Comparison and Economic Analysis more economical pavement material over life cycle cost comparison and economic analysis using primary and secondary data.
The scope of the study is, therefore, limited to evaluation of two alternative pavement types based on life cycle cost and economic advantages for sustainable road construction projects. Environmental impact and societal benefits from this sustainable road construction projects will not be fully quantifiable in this study. Because of technological differences, calibration problems and data availability limitations in our country, the researcher couldn’t use models like HDM-4 for the evaluation of user costs and environmental impacts.
- Methods/methodology
The research work is started with problem identification, which is followed by literature review, formal and informal discussion with professionals in the federal road construction sectors.
The research has then proceeded through economic analysis and life cycle cost comparison of Cement Concrete Pavement material against Asphalt Concrete material in trunk type roads of Ethiopia. Literatures include magazines, books, journals, internet etc. In parallel with literature review, an in-depth desk study has been conducted to identify construction costs, maintenance costs, environmental impacts and road user benefits of each pavement material type. During the desk study, various documents such as design manuals of different countries, technical specifications, feasibility studies reports, Engineering design reports, correspondences, progress reports, completion reports, payment certificates, statements on final account, road asset management documents etc. has been critically evaluated. Whenever there is unclear primary data or ambiguity during the desk study, further explanation or information has been obtained through informal interviews with professionals involving in road construction projects especially pavement or material Engineers, in order to maximize the clarity and to gain adequate understanding of the data for its use in analysis.
The document search was intended to collect pavement design trends, values of initial/construction costs consumed and annual maintenance or rehabilitation costs allocated from some randomly selected upgrading and rehabilitation trunk type road construction projects which are completed/substantially completed.
Then analysis and discussion has been conducted based on the primary & secondary data obtained. Finally, conclusions have been drawn and recommendations forwarded based on the finding of the study and literature reviews. The study has been conducted on projects with high traffic volumes (50 million ESAL to 80 million ESAL) of Trunk type Federal Roads of Nigeria.
Life Cycle Cost Analysis provides a methodology for computing the cost of a product or service during its lifetime. It is used to compare competing design alternatives over the lives of each alternative, considering all significant costs and benefits, expressed in equivalent monetary units (Yongyuth et al., 2012). For infrastructure assets such as roads, a large proportion of the total cost over the lifetime of these assets is incurred after construction, i.e. during their service lives. It is possible to avoid most of the “unknown” costs by introducing long-term costs into the pavement valuation processes instead of comparing only initial material and construction costs (Yongyuth et al., 2012).
Analysis period of 40 years has been determined based on the recommendation of AASHTO 1993 and in order to utilize the full design life of concrete pavement for proper comparison of the two pavement type alternatives.
- Contribution to the field of Knowledge
The study will serve a method for assessing the total cost of the facility ownership. It takes into account all cost acquiring, owning and disposing of a building, or building system. The cost of road construction consists of design expense, material extraction, construction equipment, maintenance cost, rehabilitation cost, salvage cost initial construction cost, fuel cost, time saving cost and operations cost over the entire service life of concrete over asphalt pavement. An economic analysis process known as Life Cycle Cost Analysis (LCCA) is used to evaluate the cost efficiency of alternative based on the Net Present Value (NPV) concept. It is important to evaluate the above mention cost – aspect in order to obtain optimum pavement life-cycle costs. However, pavement managers are often unable to consider each important element that may be required for performing failure maintenance tasks.
- Expected Results.
The economic evaluation compares the costs of the proposed projects with the major monetized benefits resulting from the projects to provide an indication of their value for money as currently layout. Factors considered in the economic analysis for comparison of the pavement type included initial construction costs, the expected maintenance costs and some road-user benefits in the analysis period.
Many factors influence in the selection of the type of pavement to build. Some of the main factors include: traffic, soil characteristics, climate/weather, construction considerations, recycling and cost comparison. There are also secondary factors such as: performance of similar pavements in the area, conservation of materials and energy, availability of local materials, traffic safety, traffic noise mitigation, experimental features and local preference which were discussed.
The result obtained from the life cycle cost of both alternatives indicate that the concrete pavement has a longer service life than asphalt pavement and for 1km (kilometer) road length, the life cycle cost of the concrete pavement is lower by a value of 17.3million in naira than that of asphalt pavement in forty (40) years analysis period. The 1km (kilometer) concrete pavement is therefore adjudged as an economic viable alternative over asphalt pavement due to it relatively lower life cycle cost and higher service life and as a result must be given due consideration by prospective investors. Current Life Cycle Cost Analysis (LCCA) method are analyzed in research.
