An Appraisal of Highway Maintenance Management in Nigeria
CHAPTER ONE
OBJECTIVES
The objective of this thesis is to provide assistance to sub-saharan African nations in making appropriate decision about the best type of MR&R intervention to apply to the poor state of arterial roads. Such decisions will be contextual and would answer various questions, least of which are the type and extent of distress present and the benefit cost Analysis.
A secondary objective is to provide FERMA with analysis of its mix designs and re-evaluate them to allow for more appropriate pavements to be constructed. It is recognised that these objectives need to be balanced against regional issues that include;
- Soils – condition andvariability
- Materials – quality andavailability
- Budget constraints
- Maintenancecapacity
- Traffic type andvolume
- Experience and availability ofpartitions
CHAPTER TWO
LITERATURE REVIEW
This chapter will attempt to convey the issues, principally from a transportation standpoint that are not only facing Nigeria but Africa as a whole. After having read this chapter the reader should have an appreciation of the differences between Western Transport-related issues and those being experienced in Nigeria and the reasons for them. This chapter is not intended to provide an exhaustive account of all aspects relating to transportation in Nigeria, however it will provide the necessary background and references for a more detailed account of the subject and further works, including the principles of road design and asset management.
AFRICAN TRANSPORT
The continent boasts of a population of over 900 million in the face of abundant natural resources. Yet it remains stagnated, poor and underdeveloped. One of the resounding reasons for not having the ability to reach its potential is the poor state of road infrastructure, which the World Bank (2008) highlights as a principal reason that is keeping the African continent from progressing. In Africa, inadequate transport is the norm rather than exception.
Africa is poorly serviced with roads. The road density is on the average 7km per 100 square km (AFDB, 2003), which is low when compared with other developing regions, such as Latin America and Asia with 12km and 18km respectively per 100 sq km (World bank, 2007). The significant difference is partly due to diverse levels of development in general but it also reflects the basic geographic fact that Africa is a large continent, often with vast distances between main population and production centres. The large size of the continent and the wide spread of population only raises the significance of transport in almost all development decisions. This lack of adequate transportation impacts on the level of business activity by lowering productivity and limiting the entry of new business enterprises. Business as in Africa either supply to fragmented regional markets, or restrict themselves to market opportunities with profits large enough to cover the high transport costs (Ramachandran, 2008).
CHAPTER THREE
DATA SOURCES AND RESEARCH METHODOLOGY
This chapter discusses data sources used to undertake detailed analysis of Nigerian pavement design. It also discusses classification (Taxonomy) of the data/information into a system that can be utilized by pavement Engineers and Field Engineering in Nigeria. The experimental methodology applied will define the data\information that are needed as input variable in the design, as well as the flow diagrams and decision trees for appropriate maintenance and rehabilitation interventions.
The data envelop discussed has several components as they impact pavement design, construction and maintenance. These include;
sub-grade classification, traffic, environment, pavement condition, maintenance and rehabilitation costs and service life.
The chapter also discusses computational aspects of pavement design and maintenance. This will facilitate automation of the processes and enhance productivity in the sector.
DATA SOURCES
The Nigerian Federal Road network is composed of 32,100km of asphalted roads (figure 3.1). One of the defining issues of the Federal Road network in Nigeria is the lack of reliable data. For example the current road classification distribution, according to FERMA (2007) is that 15% of the roads are ‘Very Good’ and 20% roads are “Good” yet there are no clear cut explanations on how these designations were arrived at by the Road Maintenance Management Service Department (RMMS) of the Agency. Data about the designs that were applied in building of the roads are significantly lacking. Where designs are available, literature has pointed to the fact that it is likely that they have not been applied to the specifications and therefore, data about them are rendered inadequate. Also, the “as constructed” information/drawing are not often available. It is obvious that there is a need to utilize data that can be supported.
CHAPTER FOUR
FLOW DIAGRAMS, DECISION TREES AND LIFE CYCLE COSTING
This chapter uses utilized the data and information acquired in the preceding chapter to discuss tools that can be utilized by Road Maintenance Agencies such as the Federal Roads Maintenance Agency of Nigeria to streamline their maintenance and rehabilitation interventions. It is intended that these tools provide an easy reference by which a Road Maintenance site engineer can have access to maintenance or rehabilitation interventions that suit the distress being observed at the project level. Such tools include flow diagrams and decision trees. It is also important that these streamlined maintenance and rehabilitation intervention decisions are supported by life cycle costing so that decision makers can have assurance that the correct implementation has been applied, or will be applied.
CHAPTER FIVE
CONCLUSIONS AND RECOMMENDATIONS
The state of the federal roads in Nigeria can be greatly improved through pavement design and management tools. Road have been constructed as is the case for sub-Saharan Africa in general, with little consequence of the maintenance and rehabilitation that is required to maintain the asset. Further, the roads that are in use today were constructed decades ago and have long outlived their design life. Nigeria has realized this and has responded to the need for better federal roads through the establishment of FERMA, who have a mandate to improve the federal road system through the use of pavement management and appropriate MR&R interventions. The work presented in this thesis is a viable tool for FERMA’s in her quest to create a pavement management strategy.
CONCLUSIONS
The Federal road network in Nigeria is composed of approximately 32,100km of surfaced flexible pavement structures. The state of these roads is questionable given available data on network pavement condition, although FERMA does indicate that 15% of the roads are in ‘Very Good’ condition and 20% are in ‘Good’ condition. A network assessment of the true condition of the federal roads would be a valuable tool in better streamlining the rehabilitation intervention required to improve the network.
A RONET analysis utilizing World Bank data for Nigeria was conducted. The investment required over the next ten years was found to be considerable less than that of the requirement that is quoted in the literature. It is interesting to note that the literature values are not supported with any data or explanation, so their magnitude is questionable. Certainly, the budget requirement outlined by the RONET analysis does, at the very least, provide FERMA with a starting point with which to budget towards. Once better data on the distribution condition rating for the network is determined, along with more accurate rehabilitation intervention costs, a more refined budget can be determined.
Five different traffic classifications were outlined for the federal roads in Nigeria. Essentially, they can be divided into two groups according to the level of traffic and type of wearing course. On one hand we have the low volume federal roads (ADT<1500) which are surface with a thin bituminous wearing course applied as a single seal or double surface seal. On the other side of the spectrum we have more loaded roads with high traffic volume and/or a high percentage of heavy trucks (ADT>1500) which are surfaced with either 1-lift or 2-lift of AC. A clear need exists for Nigeria to expand upon the types and designations of AC it uses, as a ‘one size fits all’ classification of binder and asphalt is not logical over a country with such vast climate and traffic variations. Focusing on more appropriate flexible pavement wearing courses that are applied with a greater level of quality control will go a long way to improving both the longevity of the surface and produce a network with a better overall pavement condition.
Condition rating curves were created for the various rehabilitation interventions for typical designs utilized for federal road in Nigeria. Drastic condition rating curves were created to better reflect the present state and rate of degradation of rehabilitation interventions. Other than increasing the life cycle cost of the pavement, the application of the drastic curve for the ranges of intervention costs did not alter the optimum rehabilitation strategy. For low volume federal roads, utilization of a 6% discount rate instead of the 12% discount rate which is applied by the World Bank for many SSA nations, altered the optimum rehabilitation strategy for the maximum condition rating curve only from a single chip seal specific rehabilitation schedule to one incorporating a double seal specific rehabilitation strategy. For all other cases, a single chip seal was more cost effective than application of a double seal over the 20 year analysis period.
For high volume or loaded roads, 1-lift of AC is more cost effective than application of two-lifts. This held true under all condition rating curves, intervention costs and discount rates.
Utilization of a cement stabilized base as part of the rehabilitation intervention had no influence on the optimum rehabilitation strategy. While this was expected for the lower traffic federal roads where the cost of stabilizing the base was disproportionately high when compared to the cost of applying the surface seal, it was not expected for the higher traffic roads. An improvement factor of 10 condition rating points and a 1-year increase in the pavement performance was apportioned to a stabilized base. It is possible that this is an underestimation and a more refined analysis would prove that stabilization would have a higher influence on the optimum rehabilitation strategy. Present Worth Cost (PWC) analysis should be applied for different stabilizers.
The work conducted in this thesis provides a good basis for a road maintenance agency like FERMA to ascertain the condition of Nigeria’s Federal road network. While assumptions have been made, out of necessity, the information obtained through the PWC analyses is immediately implementable and outlines the value of this work.
RECOMMENDATIONS
The use of assumptions in the analyses in this document is an unfortunate reality when dealing with federal road networks in the developing world. This certainly proved to be the case for Nigeria. However, the difference is that they have shown commitment to improve on their federal road network through FERMA, but also by instituting a pavement management strategy to preserve their most important national asset.
Every effort has been made to utilize the most accurate and representative data. What is required now is validation of the results that were achieved and this would provide an excellent starting point for further research. More refined cost data and condition rating of the Federal road network would be an invaluable tool. Once more data becomes available the life- cycle costs can be fine tuned and refined to better reflect not only the federal system, but also at regional levels where material and climate differences may predominate.
It is noted that application of a more reasonable discount rate of 6% does not alter the optimum rehabilitation strategy under all conditions. The PWC is much greater for all cases, which would be expected given the lower discount rate. This highlights the importance of identifying the most appropriate discount due to apply to economic analysis. A more refined discount rate will assist in better budgeting as well as the price life cycle cost for higher discount rate is much greater than for a more reasonable rate. This further demonstrates the need to use more refined input data as the intervention cost, as there is a significant cost fluctuation when varying costs are applied.
Application of an accurate discount rate and intervention cost are both of critical importance in determining a PWC that is budgetable. Improvement in intervention cost accuracy and discount rate forecasting will assist Nigeria through improved condition of their federal roads as a consequence of better roads from the outset. These two factors are critical to achieve improved pavement network condition and better fiscal management.
There is considerable price variation between the minimum and maximum costs applied for the interventions, this echoes the need to obtain more precise costing for asphalt concrete over all climate regions of Nigeria.
Validation of the benefit that different stabilization has, (eg; Lime, Nanomaterial etc) in addition to other stabilization products over cement, should be conducted as it is a common technique used throughout North America and other sub-Saharan African Nations.
Lastly, validation of the condition rating curves is essential as slight differences in pavement longevity will have impacts on the PWC and resultant optimum strategy to be applied.
SUGGESTIONS FOR FURTHER/FUTURERESEARCH
- Nanotechnology for sustainable infrastructure in the 21st
- An appraisal of Highways Maintenance by contract and direct labour operations in
- Highways maintenance in Nigeria: Lessons from other
- An appraisal of the cost management practices in the delivery of capital projects in
- A construction management perspective to the management of Federal Roads in Nigeria: A case study of Enugu – Port Harcourt Dual
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