ABSTRACT
Road failure is a major problem in most of developing countries and even the developed ones. Most of the road networks in the developing countries of Africa are in deplorable conditions. Nigeria being one of these countries is not an exception. The conditions of the roads in Nigeria were examined. The causes of these conditions of the roads in Nigeria were articulated and their effects to the citizen, government and the economy of the country were highlighted and solutions to these problems given in the form of recommendations that will remedy the situation. Some of the identified causes were; poor design and construction, poor maintenance of already built highways, use of low quality materials in construction, poor workmanship and poor supervision of construction work and the plying of heavy traffic that were not meant for the road on the road.
Some of the recommendations to remedy the situation are; Use of the appropriate design of the roads, avoiding unnecessary congestion of the roads with traffic especially heavy traffics that were not meant for the roads in the first place, prompt maintenance of the roads, application of suitable construction material in the construction of the roads, applying appropriate tests to the soil in road construction, use of qualified engineering personnel in road construction and the application of sanctions for highway failures. This paper takes a critical look at this common phenomenon. The paper looks at functional failure of flexible pavement by reviewing related literature such as journals and textbooks, and find out that moisture penetration, inadequate drainages system and lack of in depth technical information during design stages are few reasons responsible for road defects, which if left unchecked could result to road failure.
CHAPTER ONE
1.0 INTRODUCTION
The catalogue on road defects (1992) refers to road defects as the visible evidence of an undesirable condition in the pavement affecting serviceability, structural condition or appearance.
The definition of a "road defect" includes any part of a road, highway, or construction site that does not meet the regulations for a safe road. In Nigeria the defects that most often cause injuries to people or damage to vehicles include: inadequate road shoulders, lanes that are uneven, pavement that is uneven, improperly marked signs, malfunctioning stop lights, construction negligence, and municipal negligence. These leads to accidents on Nigeria roads which lead the national emergency agency NEMA to put up a programme that engaged the competent hands from other stake holders such as the Nigerian police, Nigerian army, Nigerian security and civil defense corps, federal road safety commission, National air space management authority, Nigerian red cross, the states ministries of health and environment. For the programme, national and state emergency agencies were to train the volunteers (Onwubiko 2010). NEMA also did a study on the major causes of accidents across the country in collaboration with the federal road safety commission in close partnership with members of some state emergency management agencies in some flash points like Tafa junction, Forest/ Mararaba to Jos in Kaduna state and made recommendations to some state governments on the urgent need to decongest some major federal highways which passed through these states and are now used by heavy duty vehicles drivers as transit camps thereby constituting veritable sources of road disaster. From these studies it indicated that the deplorable conditions of the roads contribute to high level of accident on the roads. Onwubiko (2010) stated that Nigerian roads were death traps. In the developing world which includes Nigeria, road network is the most developed transport mode and the vastest in usage. The Nigerian government over the years has tried to construct and rehabilitated the roads. Considerable interest has been shown by the government to road investment (see table2). The issue has been the extent these interests has been driven to achieve the desired result. According to Oguara(2010), roads represent the major areas of investment in transportation and are the most dominant travel mode accounting for over 90% of passenger and goods transport in Nigeria. One of the main problems of road work in Nigeria is the lack adequate informational data on the Nigerian roads. Some studies have been done on the state of Nigerian roads. Ette (2010) stated that there was a road net work study that was commissioned in 1998/99. This study covered all inters- urban roads which had a traffic of more than 30 vehicles/day and a total length of around 53,000km. Urban roads were not included in this study. The outcome of the study is shown in table 1 below.
The problems of the Nigerian roads are looked into in this paper and their causes analyzed with the proffering of solutions to these problems.
1.1 OBJECTIVE OF THE STUDY
The objective of this work is to looks at functional failure of highway pavement, by reviewing related literature such as journals and textbooks, and find out that moisture penetration, inadequate drainages system and lack of in depth technical information during design stages are few reasons responsible for road defects, which if left unchecked could result to road failure.
1.2 SCOPE OF THE STUDY
Highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade. The pavement structure should be able to provide a surface of acceptable riding quality, adequate skid resistance, favorable light reacting characteristics, and low noise pollution. The major Flexible pavement failures are fatigue cracking, rutting, and thermal cracking. The fatigue cracking of flexible pavement is due to horizontal tensile strain at the bottom of the asphaltic concrete. The failure criterion relates allowable number of load repetitions to tensile strain and this relation can be determined in the laboratory fatigue test on asphaltic concrete specimens. Rutting occurs only on flexible pavements as indicated by permanent deformation or rut depth along wheel load path. Two design methods have been used to control rutting: one to limit the vertical compressive strain on the top of sub-grade and other to limit rutting to a tolerable amount (12 mm normally. Thermal cracking includes both low temperature cracking and thermal fatigue cracking.
1.3 CLASSIFICATION OF NIGERIAN ROADS
Nigeria has about 200,000 km of roads spread all over the country. These roads are made up of over 32,000 km of federal roads spread over the thirty six states and the federal capital, over 30,000 km of state roads and over 130,000 km of local government roads. Within the states, the local government roads are further classified into urban and rural roads.
FEDERAL ROADS
In one of its publications in June 2011, the federal ministry of works reported that it had over thirty five thousand kilometres of federal roads and bridges in the thirty six states of the federation and the federal capital territory, Abuja. These roads are divided into the federal trunk ‘A’ roads and the federal trunk ‘F’ roads. The federal trunk ‘A’ roads are those under the federal government ownership and they are developed and maintained by the federal government while the federal trunk ‘F’ roads are those that were formerly under the state ownership, but were taken over by the federal government, with a view to upgrading them to federal highway standards (Nnanna etal 2003). The faults on most of the Nigerian federal roads are; depressions on the road surfaces, presence of pot holes and cracks, development of gulley due to erosion, washing away of the road shoulders, faulty street lights, faulty drainage systems , faulty traffic signals and wiping off of pavement markings.
STATE ROADS
The state roads are classified as the state trunk ‘B’ roads. These are the roads under the ownership and management of the various state governments.
LOCAL GOVERNMENT ROADS.
These are classified as the local government trunk ‘C’ roads. They are the roads under the ownership and management of the local governments in the country. These roads are divided into the urban, rural and village access roads.
URBAN ROADS.
In Nigeria, these are the roads that are in the urban areas. They account for over twenty one kilometres of Nigerian roads. They include township streets, lanes, cul-de-sac and avenues. Most of these roads are tarred while some are still untarred. In the state capitals the advanced urban roads posses traffic facilities like street lights, drainage facilities, pavement markings and traffic signals. In this country, the main faults on most of our urban roads are almost the same as the ones on the federal and state roads; they are; depressions on the road surfaces, presence of pot holes and cracks, development of gulley due to erosion, washing away of the road shoulders, faulty street lights, faulty drainage systems, faulty traffic signals and wiping off of pavement markings.
RURAL ROADS
In Nigeria, rural roads account for over 72,000 km of roads in the country. These are roads that are found in the remote country parts of the nation. They are mainly earth roads, but with recent developments in the rural areas some of them are now lightly tarred. Here, most of the faults on our urban roads are also available on our rural roads. Faults like the depression of the road surfaces, presence of potholes, cracks, gulley and the wearing away of the road surfaces are rampant.
VILLAGE ACCESS ROADS
In the local governments these are minor roads that provide access within the various villages we have in the country. They are mainly earth roads. The level of under development of these roads reduces them to the level of foot paths. The village access roads account for 35000 km of Nigerian roads
1.4 NATURE OF NIGERIAN ROADS
With the faults mentioned below (in chapter two of this work) are associated with the roads in Nigeria, the Nigerian roads can be said to be non-functioning. A road that is functioning should be able to possess the following characteristics;
- The road should be able to give an all- weather support to vehicles. That is, it should bear and distribute wheel loads to within the bearing capacity of the sub grade soil.
- It should boast of adequate drainage facilities. This means that there should be free flow of water and flood along its drainage system so that water will not flow back on to the pavement to cause one problem or the other.
- It should provide adequate skid resistance. This implied that it should provide enough frictional adhesion to vehicle tyres especially during acceleration, deceleration and cornering.
- There should be adequate high way geometrical facilities like good geometric design of road widths, intersections, side slopes, sight distance that make for easy movement and passing with safety at established level of service
1.5 CAUSES OF THE FAILURES OF THE HIGHWAYS
There are many different causes of high way failures. Some of the causes on the Nigerian highway pavement failure are;
1. POOR DESIGN AND CONSTRUCTION.
Failures like cracking in rigid pavement are caused by inadequate curing of concrete, settlement, movement or restraint at joints may also lead to the development of cracks and subsequent failure. Most of the roads in the country are designed in the ministries or by consultants some of who are not within the environment of the road work. This leads to a situation where preliminary studies of the environment that will help the design and construction decisions are not done. This leads to poor understanding of the road environment which subsequently leads to poor road design and construction. Oguara (2010), then said that to save the road network from total collapse, requires good and efficient management which had to be done in a pragmatic and organized frame work.
2. HEAVY TRAFFIC
All road surfaces wear under the action of traffic, particularly during the very early life of the road. But within a short time the micro texture reaches an equilibrium level and thereafter the low speed skidding resistance remains reasonably constant. However, the action of traffic continues to wear the macro surface texture and thus gradually reduces the high speed skidding resistance. Oguara (2010) stated that with the increase of traffic loads both in terms of numbers and axle loads due to increased economic and developmental activities in the country, the road network was experiencing a systematic deterioration equivalent to an asset loss of about N80 billion due to road deterioration and vehicle operating cost of N53.8billion per annum. One of the defects caused by heavy traffic on the road is the deformation of the road way which is the change in a road surface from the intended profile. This results due to the application of overload that is beyond what the roadway is designed and constructed for. The Nigerian roads are overloaded with traffics that would have been conveyed through other transport modes than the road. Hence the director general of the Nigerian institute of transport technology Tuesday 16th august 2011 stated that the absence of sound rail transport system, over loaded trucks and general road abuse arising from poor maintenance are the reasons for the poor state of roads in Nigeria. He said that the above factors had to be addressed if roads in Nigeria were to last longer. He stated that the Nigerian roads that were designed to last twenty years experience a reduced longevity because of lack of control over the loading usage and the crumbling of the Nigerian railway system (Okigbo 2012).
3. POOR MAINTENANCE CULTURE.
Even if the roads are well built they need adequate maintenance for sustainability. One of the main problems of highway development in Nigeria is maintenance. The roads are rarely maintained and whenever maintenance is attempted it is done haphazardly. According to Oguara (2010), the financing of the maintenance, rehabilitation and conservation of the roads network in Nigeria had always been left to the government at the federal, state and local government levels who because of their lack of maintenance culture do not release funds for road maintenance at the appropriate time. The road network was therefore left to deteriorate to the extent that portions of the federal trunk A roads became impassable. Igomu (
2011) stated that roads worldwide were considered critical infrastructure in any nation’s life and were paid premium attention. He said that was not the case with
Nigeria, as many of the roads had exceeded their structural life and had become huge slaughter slabs as they had been denied all forms of maintenance. Adequate fund are not budgeted for maintenance in Nigeria. Budgetary process is cumbersome and agencies in charge of maintenance are not well monitored for efficient work. In Lagos, areas like Mushin, Olosa, Ojuwoye, Daleko, Moshalashi, Palm avenue and many others have collapsed under the watchful eyes of the local government. Also an area like Kirikiri town in Apapa, mafoluku, Oshodi, as well as other places with high commercial concentration are not spared. There is lack of local government presence in these areas in the area of road maintenance. It has become an open truth that roads under the local governments are generally in a state of total disrepair. Checks over the yeas have revealed that on record, billions of naira had been allocated for repair works on the country’s roads only for minor repair works to be effected.
4. POOR HIGHWAY FACILITIES.
Highway facilities like drainages when not in use or lacking in performance result in some of the environmental related defects like roadway deformations and pot holes. As at 2011, virtually all roads in the country have become hubs of intractable snarl-ups and ghastly motor accidents, as unsuspecting motorists speed into deadly craters and monstrous potholes (Igomu 2011). Every part of Nigeria’s main roads is not spared the onslaught of deadly potholes that have inflicted both physical and emotional torture on motorists. The situation degenerates by the day aided by the rains and failed drainages filled with silts.
5. POOR LABORATORY AND INSITU TESTS ON SOIL.
There is the need for the adequate test of the soil and the materials used for road construction. Unfortunately this is not always done. Since most of the construction companies in the country could not afford adequate laboratory facilities they should make use of the laboratories in the universities and polytechnics that have better facilities in the country for the test of their construction materials. Even the road research institute in Ogun state can help if the facilities are adequate.
6. USE OF LOW QUALITY MATERIALS.
Use of low quality aggregate adversely affects the quality of the roads in Nigeria. This sometimes occurs in the form of the improper grading of aggregates for sub base and poor sub grade soil. The use of extreme cohesive and expansive soil as sub grade soil results in prolonged consolidation and unnecessary settlement of the roadway. The use of soil of low bearing capacity leads to the failure of the sub grade soil.
7. POOR WORKMANSHIP.
Most of the workmen in construction sites in Nigeria are not well trained. This is especially among the artisans and the craftsmen. Sometimes the technicians, the technologists and even the engineers are not given adequate practical training. Inappropriate application of materials by the workmen is mostly due to low knowledge of the works by the workmen. Operations like soil compaction and stabilization are inadequately done due to low knowledge of the workers.
8. POOR SUPERVISION.
In Nigeria most of the supervisions of construction work are done by the engineers and other middle level supervisors like the foremen. Some of these supervisors who have low knowledge of the work find it difficult to deliver adequate supervision at the site. Some of the faults on the roadway like depressions, cracks and even pothole can occur due to improper workmanship that resulted from wrong supervision. Wrong supervision could result to improper application of the material and operation of the works. Operations like the application of bituminous material, compaction of the soil etc could be messed up because of improper supervision.
9. LOW KNOWLEDGE BASE.
Lack of modern method of road construction on the part of the old engineers and low curriculum standards on the part of the young engineers are some of the problem of road construction in the country. Even the multinational construction companies in the country their workers display inadequate knowledge of the process of road construction. There are modern methods and standards of road design and construction available today.
Our road contractors have to avail themselves of the used of these available new and modern methods of road construction and maintenance.
10. NO LOCAL STANDARD OF PRACTICE.
There is the need for adequate monitoring and control in the local construction process. This can be done by the provision of a standard method of practice which will be strictly followed, monitored and maintained. The professional bodies in the country will play a very important role at this stage. They should be able to provide a local standard of practice for the country, maintain it and monitor compliance to the use of the standard. This is because a local standard will take cognisance of the local peculiarities that will affect the environment where road works are located.
11. INADEQUATE SANCTIONS FOR HIGHWAY FAILURES.
There have been records of failures on Nigerian highways. No body or agency has ever been held responsible. Even the roads constructed by the multi-national companies some of them start failing before the construction work are completed. Even when accident occurs it is generally blamed on the behaviour of the driver without looking at the effects of the nature of the road. The main factors that contribute to the cause of accident are driver behaviour, nature of vehicle and the nature of the road. In this country whenever accident occur we emphasise the first factor while de-emphasising the effects of the other two factors which make tremendous contribution to the cause of accidents.
12. NOT CO-OPTING LOCAL PROFESSIONAL BODIES IN HIGHWAY DESIGN, CONSTRUCTION AND MAINTENANCE.
As earlier mentioned, the professional bodies have a lot of contribution to make to the construction of highways in this country. At present in the Nigeria the professional bodies have not been given adequate chance to contribute to road construction and maintenance in the country. The whole work of road construction and maintenance in the country is left at the mercy of expatriate companies that need to understand the local terrain and situation of our roads to enable them construct appropriately. This information can be provided by the local professional bodies that have more knowledge of the local environment. The professional bodies can even act as checks and monitors to the construction firm on road work in the country.
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