Home Papers INADEQUACIES IN CIVIL ENGINEERING PRACTICE IN NIGERIA: SOME CASES IN HIGHWAY ENGINEERING

INADEQUACIES IN CIVIL ENGINEERING PRACTICE IN NIGERIA: SOME CASES IN HIGHWAY ENGINEERING

INADEQUACIES IN CIVIL ENGINEERING PRACTICE IN NIGERIA: SOME CASES IN HIGHWAY ENGINEERING By Douglas O. A. Osula

ABSTRACT

This work makes a presentation on inadequacies in civil engineering practice in Nigeria, and problems that arise from them. A brief a tour is taken through some cases in highway engineering to drive home the need to re-order practice in the right and appropriate directions so as to prevent premature failures of civil engineering infrastructure in Nigeria. A charge is made to the NICE for concerted efforts towards developing standards and codes of practice that are appropriate for the Nigerian setting. The NICE is also advised to organize courses regularly to re-educate practicing engineers to update their knowledge of the profession as presented in new publications that result from continuing research and development works in civil engineering. Areas in which research and development efforts may need to be directed and particularised for the Nigerian setting are highlighted.

INTRODUCTION

Many inadequacies can be said attend design amd construction efforts in Nigeria. This assertion id attested to by the numerous failures that occur in civil engineering infrastructure in the county. Failures of building structures, roads and dams are but a few examples. It is the purpose of this presentation to take a tour through some of these inadequacies that the experience of the presenter makes him competent to duel on. The cases taken for discussion herein are all in highway engineering and are; materials’ testing, earthworks estimation, pavement design, and pavement maintenance. The cases are discussed in the order listed.

  1. MATERIALS’ TESTING

There are many aspects of materials testing with respect to highway engineering. But the one considered herein is that which relates to the determination of the California Bearing Ratio (CBR) of subgrade material for use as input data in pavement design procedures. Others concern majorly characterization of materials (aggregates, soils, bitumen) for the purpose of their selection for use for the constructional works at hand.

The variable CBR is an input in all pavement design methods known to the presenter. It is used majorly as a measure of the strength of the subgrade soil material. Being so, the sample used for its measurement should be collected at the point of the road cross section where the subgrade surface is to be. Thus, also, the collection of the material for a cut section should be at the formation surface (i.e., layer after the bottom of the cut), no matter how deep the cut is. Similarly, it is the material that is to be used for constructing the fill at the formation surface (i.e., top layer of the fill) that should be used as the sample for determining the CBR. These should be so if the characteristics of the material truly representing the subgrade are to be estimated.

The sad truth of the matter is that most highway designers in Nigeria do not go beyond about 1 metre after removal of the top soil. In some instances, the top soil is within the 1 metre depth. The 1 metre depth is only suitable for at-grade formation (where there is cut or fill). From the experience of the presenter, soil properties vary more vertically than horizontally. The premature failures on most Nigerian pavements may be traceable to this kind of non-observance of good practice that eventually lead to inadequacies or deficiencies that could have been avoided.

  1. EARTHWORKS ESTIMATION

There are also many aspects of earthworks estimation that can be discussed, starting from the simple arithmetic of calculating the areas of cut and fill sections. The arithmetic continues to the calculation of volumes between sections and ends with corrections for shrinkage and bulking. Beyond here, the resulting data are used for plotting the mass-haul diagram that is eventually used for the estimation of the major earthworks bill items of cut-to-fill, cut-to-spoil, borrow-to-fill, and the overhaul quantities.

By definition, a mass-haul diagram (American terminology – mass diagram) is a continuous curve showing the cumulative algebraic sum of the meterage (or volume, cuts as positive and fills as negative, conventionally) from some initial station to any succeeding station. The points on the curve are plotted with reference to a horizontal scale of distance (stations along the length of the road) and a vertical scale of volume, in cubic metres. The word “haul” usually has two meanings; it may refer to the distance through which excavated material is moved, or in a technical sense, to the metre-stations, i.e., the volume of material multiplied by the distance over which it is moved. The latter meaning is usually preferred to the former and this is how it is used in the interpretation of the mass-haul diagram estimations of earthworks items in the bill of quantities.

Mass-haul diagrams are a useful tool to the highway or railway engineer during the design as well as during the construction of the facility. Some of the several ways in which use can be made of mass-haul diagrams are:

  • determination of the most economical vertical alignment (i.e. profile) by trying several formation surfaces with each one having a mass haul diagram plotted for it at the design stage;
  • determination of the amount of overhaul and the most economical distribution of excavated materials with a view to getting a good estimate of the overall cost of the earthworks as a guide to budget forecasting for the project;
  • allocation of plants and machinery to the different sections of the project and location of sites for borrow pits and spoil heaps as well as the determination of the directions of haulage

For the first way of using the mass-haul diagram, what it means is the fact that for a road whose horizontal alignment has been fixed, it is the earthworks cost that can be varied if there is need to examine the possibility of reducing cost of construction, since the cost of the pavement remaining substantially unchanged since length of the road may not change substantially though changes have occurred in slopes or gradients. Following this reduction that can be made in cost the of earthworks (through the redesign or modification of the vertical alignment, i.e., by reducing cut depths and fill heights so long as constraints are met), are the reductions that are made in virtually all other items of the earthworks and site clearance bill as well as the bill for culverts and drains. Thus if the mass-haul diagram is not used for this reason, what may happen is that earthworks cost is underestimated (the more usual case in practice from the experience of the presenter) or overestimated. It is through this kind of overestimation that eventually leads to increases in final cost of road projects, and hence seemingly great loss to the client.

The second way of using the mass-haul diagram does not come into play only during the design of the vertical alignment, but also after the completion of the constructional works because the mass-haul diagram is the basis (unknown to many highway engineers) of the final payment for earthworks at the completion of the project. This is where the non-use of the mass-haul diagram has serious implications for the overall cost of the project. This is because even if it is not used during the design stage of the vertical alignment and in estimation of the quantities in the bill of quantities, it is imperative that it is used in preparing the earthworks cost for final payment to the contractor.

The import of the discussion on using the masshaul diagram at least at the completion of the constructional work is that while existing commercial computer packages go as far as providing plots of the mass-haul diagram, non as yet uses it for estimating the earthworks cut-to-fill, borrow-to-fill (and most importantly cut to spoil, due to deficiency in good quality materials from cut sections) and the overhauls associated with them. The engineer needs to use the mass-haul diagram with a knowledge of such things as the free haul distance and the limit of economical haul to estimate the overhaul distance and hence the overhauls. Thus from the presentation in this section it is clear that the non use of the mass-haul diagram is a serious inadequacy which needs to be corrected by all concerned.

Finally, the third way of using mass-haul diagram listed above (i.e., allocation of plants and machinery to the different sections of the project and location of sites for borrow pits and spoil heaps as well as the determination of the directions of haulage) is of paramount importance to the engineer who practices as a contractor. Needless to say efficient allocation of machinery saves time and money.

  1. PAVEMENT DESIGN

The pavement may be considered the most important of the road component since on it bears directly the wheel loads. This is why particular attention should be paid to its design. There are several new methods of pavement design which give desired results. Sadly, however, the method that is still incorporated in the Nigerian Highway Design Manual (FMW&H Highway Manual Part 1, Design) can be said to be the oldest in history, and this is the Road Research Laboratory Note No. RN2803/MDAHGB, whose main features are as shown in the Appendix.

The excerpts below cover the design procedure of this design manual;

Clause 1-306.04 Design Procedure for Flexible Pavements.

(1) Traffic – The anticipated traffic for the design life of the pavement must be determined. This figure will be expressed as the number of vehicles per day exceeding 3 tons loaded weight.

(2) Evaluation of Subgrade, Subbase and Base Materials:

Materials selected for use in the construction of a flexible pavement must be evaluated to provide information for an adequate and economical design. The materials must also be checked to determine quality and to establish compaction requirements. The mechanical strength test to be used will be the CBR.

(3) Design Procedure: After the CBR value for the subgrade and the estimate of traffic have been determined, the thickness of the pavement structure can be determined from figure 1-306.1. The values from the chart should be rounded upward to the nearest inch.

(4) Minimum Surfacing Thickness: The recommended minimum asphalt surfacing thickness is as follows:

Light Traffic 2in. (50mm)

Medium Traffic 3 in. (75mm)

Heavy Traffic 4in (100mm)

General Procedure for Pavement Design

The design of a new road pavement follows three main steps, namely;

  1. estimation of the amount of traffic that will use the road over the selected design life (usually 20 years for flexible pavements, 40 years for rigid pavements and for flexible pavements in urban areas),
  2. assessment of the strength of the subgrade (usually in the form of CBR for flexible pavements or modulus of subgrade reaction for rigid pavements) over which the pavement is to be placed,
  3. selecting, on the basis of (1) and (2), the most economical combination of pavement materials and layer thicknesses that will be adequate in providing satisfactory service over the design life of the pavement with only routine maintenance.

These three steps apply, with minor variations as the case may be, to both flexible and rigid pavement design. The presentation herein is however limited to methods of designing flexible pavements, since they form the greater proportion of paved roads.

The RRL method, which has come to be commonly referred to as the CBR method, will now be analysed with respect to these three steps, to show its inadequacies. In this method only 3-ton vehicles are considered as against the wide spectrum of vehicles that can also cause damage to the pavement. Also, vehicle load repetition is not considered, i.e., no projection of traffic to future year, taken as the end of the service life of the pavement. Probably, the most serious shortcoming is that differences in the structural properties of the pavement layer materials are not accounted for since only CBR values represent them. The CBR is a measure of strength (an arbitrary measure for that matter) and not of resilience (or stamina) of a pavement layer material. Thus different materials that have the same CBR values will fail at different times because of the differences in their resilience. After this analysis, the verdict no doubt is that it is inappropriate for present day situation based on the advances in research and development over the years.

Although some consulting firms in Nigeria use better and newer methods, many others still use this RRL method for pavement design. Three of these other methods are

  1. The TRRL Road Note 29 (RN 29 for short) design method,
  2. The TRRL Laboratory Report 1132 (LR 1132 for short) design method,
  3. The Asphalt Institute Manual Series 1 (MS-1 for short) design method.

The TRRL RN 29 replaced the RRL Note No. RN2803/MDAHGB in the United Kingdom (UK). It has found extensive use in other countries of similar climatic conditions and even in countries of very dissimilar conditions. The step by step procedure is as below:

  1. Find number of commercial vehicles per day at time of construction, and traffic growth rate,
  2. Decide on design life,
  3. From chart for particular growth rate obtain cumulative number of commercial vehicles for the design life,
  4. Multiply this number by the appropriate factor from to obtain cumulative number of axle standard loads (factor is based on type of road),
  5. Convert number of cumulative axle loads to equivalent standard axles;
  6. From appropriate chart obtain the subbase thickness for the appropriate cumulative number of standard axles,
  7. From appropriate charts obtain the thicknesses for the base and surfacing for the appropriate cumulative number of standard axle loads for different types of roadbases i.e. rolled asphalt roadbase, dense macadam roadbase, lean concrete, soil-cement and cement-bound granular roadbases, and wet mix and dry-bound macadam.

While one vehicle type, the commercial vehicle (defined as a vehicle with a minimum weight of 1500 kg), is stipulated in step 3 above, the TRRL RN 29 also makes provisions for deriving the standard axle, ESAL, (defined as an axle that weighs 8200kg) equivalent for use in the design.

The TRRL LR 1132 design method

As expected, being both developed in the United Kingdom, the TRRL RN 29 and the TRRL LR 1132 methods are not so different. The differences arise from the fact that while RN 29 was based on a failure criterion of 20 mm rut depth, the TRRL LR 1132 was based on a stricter rut depth criterion of 10mm. The main feature of TRRL LR 1132 is that the subbase depth is fixed at 225mm, while the cumulative number of standard axles is estimated by multiplying the cumulative number of commercials by a “vehicle damage factor.” The vehicle damage factor is calculated for any mid-term year based on the 24-hour annual average daily flow (AADF) of commercial vehicles for that year (Powell et al., 1984). Comparative, since based on a stricter failure criterion, the TRRL LR 1132 gives a more conservative pavement thickness than the TRRL RN 29. It also makes provision for design of pavements for heavy vehicles as against only the commercial vehicle definition used in RN 29.

The flexible pavement design method currently being used in the UK, the HD 14/87 design method (Department of Transport 1987), is one derived from the TRRL LR 1132 using only 2% traffic growth, and still retains the provision for design of pavements for heavy vehicles. It is based on using only 50 and 100 penetration grade bitumen and other pavement materials in the UK. Thus it is not recommended for use in Nigeria.

The Asphalt Institute method

The Asphalt Institute method is based on estimating what is called “design thickness”, expressed in terms of a “Full-Depth asphalt pavement thickness.” The Asphalt Institute defines a Full-Depth asphalt pavement as one having asphaltic mixtures for all layers above the sub-grade or improved sub-grade. Thus the “design thickness” of a pavement is the thickness of Full-Depth asphalt pavement for a particular design problem. Having obtained “design thickness” the required thickness of the pavement layers are scaled-off or derived from it by using the “substitution ratios” appropriate to the materials of the layers.

The latest edition (The Asphalt Institute, 1999) presents a multi layered elastic design approach to pavement thickness design, rather than empirical. In the procedure, the assignment is to determine the full-depth asphalt pavement that will withstand the critical vertical compressive strain on the surface of the subgrade.

The Asphalt Institute originally had only the MS-1 for all classes of vehicles. There is now the Manual Series 23 (MS-23), specifically for the design of pavements for the class of vehicles with heavy wheel loads, just as in the British HD 14/87.

What is worth noting is that both British GH 14/87 and Asphalt Institute MS-1 have provisions for pavement design for staged construction. It is optional in the MS-1 method, but imperative in the HD 14/87, hence the 40-year design life usually used for the pavement design. The first stage is for the first 20 years.

General Comments on Pavement Design

From the presentation above, it is clear that of the four methods of pavement design discussed, only the RRL Note No. RN2803/MDAHGB does not consider the appropriate ingredients for use in pavement design. The shortcomings are glaring. Comparatively, its design product is usually a gross underestimation of the requirements for an adequate pavement.

As mentioned earlier, the TRRL LR 1132 gives a more conservative pavement thickness than the TRRL RN 29. The Asphalt Institute method and the TRRL LR 1132 give comparable results. However, the Asphalt Institute method is considered the most rational of the methods discussed herein. The author recommends this method to every practicing engineer involved in pavement design in Nigeria.

For research and development purposes, especially for the Nigerian setting, mention needs to be made of what can be referred to as the latest approach to pavement design, i.e., the mechanistic-empirical (ME) approach, which is currently favoured for use in the United States of America (USA). While the MS-1 is based on a multilayered elastic design approach ton pavement thickness design that converts the effects of different vehicle loads to that an equivalent standard axle load (ESAL), the ME approach is said (Wang et al. 2007) to use traffic axle loads to calculate directly the stress, strains and displacement within the pavement structure. However, according to Wang et al. “how to collect and project traffic data to meet the new design requirements has become a common concern” Solving the problem presented by the aspect of data collection should be considered a major area to research into in Nigeria. This being the beginning of the design process, it needs to be done well otherwise all else is wasted effort that will usually lead to premature failures and losses in both time and financial resources. It is encouraging, however, that research works have begun in the general area of ME approach to pavement design (see for example Olowosulu (2005), whose work shows more conservative thicknesses are obtained by using the ME approach). The presenter urges more efforts in the specific area of traffic data collection and projection. For example, according to Stokes and Bank (2004), studies have shown that the ESAL factor for passenger cars is about 0.0008. The ESAL factors for heavy trucks, on the other hand, approach 2.4 when loaded to the legal limit and can be as high as 10 for overloaded trucks. It can be said overloading of vehicles (even passenger cars) is the norm in Nigeria. Thus research is needed to establish axle equivalence factors appropriate for vehicle loading conditions in Nigeria.

On the everyday highway operation aspect, it is recommended that strict compliance with vehicle axle load limits should be enforced on the highway.

The ESAL factor of a vehicle of a specific weight is the ratio that relates the damage caused by the vehicle to that caused an 8,200 kg (18,000 lb) axle. According to Stokes and Bank (2004), the of this axle load standard stems from the maximum legal axle loading in effect at the time many pavement design methods were developed.

Two existing design manuals using the ME approach are those of ARA, Inc. ERES Consultants Division (2003) and ARA, Inc. (2006).

  1. PAVEMENT MAINTENANCE

It is considered logical to conclude this presentation with inadequacies in pavement maintenance procedures. The aspect of the procedures to be discussed is pavement evaluation. The presenter has had considerable experience in maintenance through supervision of contracted maintenance projects. The defunct Petroleum Trust Fund (PTF) afforded opportunity of part of the experience.

To start with, it is to be noted that pavement maintenance is only a part of highway maintenance. It is being given special attention here because it can be said to be the most important in most cases. However, all efforts at implementing a pavement maintenance intervention programme can be rubbished if first things are not done first.

The first thing in a pavement maintenance intervention programme (after road inspection) is pavement condition survey, characterised majorly by the measurement of the surface roughness (or irregularity) and the structural integrity of the pavement. The exercises are carried out through non-destructive tests that do not cause much disruption to traffic movement on the road. It is the results of these two exercises that determine the type of intervention required for a particular pavement maintenance problem. From the experience of the presenter, these exercises have never followed road inspection or preceded the actual maintenance project in the present day Nigeria. As expected, the results of maintenance have been woeful, with patched sections failing shortly after patching and overlayed section not performing better. A brief description of these measurements and the equipments used for measuring them are presented below

Road Roughness Measurement

This equipment first developed used for the determination of the roughness of a road surface is also called “roughometer”. Roughness here is not in anyway related to the skid resistance qualities of the road surface. Skid resistance is a measure of the slipperiness or non-slipperiness of a road surface. While it has a direct bearing on accident proneness of a road surface, especially during wet weather conditions, it has no bearing on the riding comfort because the surface unevenness is not large enough to cause discomfort i.e. bumping of the vehicle. For the case of roughness, the unevenness usually spreads beyond the surfacing, resulting in very large and readily noticeable bumps and depressions, such that the downward and upward movements of the vehicle wheels result in jolting of passengers and hence discomfort. Very definitely, one can say that the skid resistance of a road surface is a direct reflection of the characteristics of the aggregates (polishing value as measured by the Los Angeles Abrasion test) and the quantity and softness of the bituminious material. Simply put, only the characteristics of the road surface as exposed to the atmosphere affect skid resistance, while road roughness is a result of the contributions from all the layers of the pavement. The latter, as measured by the roughometer, gives an indication of the riding quality of the road. It therefore, has a bearing on the strength of the pavement.

The bump integrator (as the roughometer is also called) , which is best suited for the monitoring of riding quality of roads where nominal traffic speeds are less than about 80km/h (50mph), consists of a single-wheel trailer. In operation it is towed along the road at a constant speed of 32km/h (20mph). This speed is rather slow if measurements are to be made on high-speed roads. For high speed roads, however, a faster equipment called the high-speed profilometer is preferred. There ns also the Meyes Meter (available in the Pavement Evaluation Unit of the Federal Ministry of Works, at Katabu, Kaduna, but only last used by the Texas Research and Development Unit in the 1980s to the best of the knowledge of the presenter, which can also measure roughness at the speed of normal traffic.

The bump integrator trailer is a heavy rectangular chassis supported on one pneumatic-tyred wheel by two single leaf springs positioned one to each side of the wheel. There are two dashpot assemblies, fixed between the chassis frame and wheel axle. The dashpots provide viscous damping. The integrator unit is mounted on one side of the chassis. Its function is to detect the total downward movement of the wheel axle relative to the chassis. The distance travelled along the road is measured by recording the number of revolutions of the wheel.

Use of BI Measurements

The value of the BI – measured irregularity index is an indication of the condition of the road surface. Works at the TRRL have shown that a correlation exists between the BI index “r” and the road conditions as indicated in the Table 1 (After Jordan and Young, 1981). A pavement whose roughness index falls in the very poor/poor and poor/acceptable ride quality categories will need its structural integrity investigated.

TABLE 1. Correlation between BI index and road surface condition

Ride quality of Road “r” for Roads with traffic speeds less than 65kph “r” for Roads with traffic speeds in the range 65 – 80kph
Ride – very poor/poor 318 – 413 286 – 413
Ride – poor/acceptable 238 – 317 199 – 286
Ride – acceptable/very good 119 – 237 119 – 198

International Roughness Index

Since the advent of the Bump Integrator described above for measuring roughness index, other equipments and methods of measuring roughness index have been developed. It is thus clear that there will be differences in the values obtained for roughness index by each equipment. It has thus been necessary to have a universal basis of interpreting the different roughness values. The universal measure is called international roughness index, IRI. The IRI is very well described in the TRL Overseas Road Note 18 (Transport Research Laboratory 1999). Converting the roughness index to the international roughness index is necessary if a loan is to be obtained from the International Monetary Fund (IMF) or the World Bank or any other international lending agency, for implementing the maintenance intervention programme.

Measurement of Structural Integrity of the Pavement

With the ride quality of the road determined and the type and surface extent of the distresses on the road also established (from road inspection), it is now desired to measure the carrying capacity or the structural integrity of the pavement. This is done usually by carrying out deflection measurements on the road surface. As with the BI measurement, it is a non-destructive test. Deflection measurements can be carried out in a variety of ways. Each measures the elastic response at the surface of the pavement subjected to a known load. The assumption is that the magnitude of the elastic response so measured may be used to determine the overall condition and the existing life as well as the remaining life of the pavement

The first of these deflection measuring devices and the one that has become the standard device is the Benkelman Beam. It was devised by Dr. A.C. Bendelman in the U.S.A. It is widely used in the world and has come to be known in many countries as the Deflection Beam (DB).

The principle of deflection measurements is that a road subjected to surface loading usually has an accompanying deformation or deflection. (Deflection in the sense that after the removal of the load, the road surface returns to its original position). The size of this deflection is an indication of the road pavement’s strength in the inverse sense. This means that the higher the deflection the weaker the pavement.

The deflection beam is widely used all over the world, and various countries employ various operating procedures.

There are other deflection measuring devices. Two of these are the Dynaflect (also available in the Pavement Evaluation Unit of the Federal Ministry of Works, at Katabu, Kaduna) and the Falling Weight Deflectometer. These differ markedly from the Deflection Beam in that the loads used are smaller and are not applied through rolling wheels. Since the rolling wheel load application resembles the real life load application on pavements more closely, the Benkelman Beam is preferred and has in fact become a standard equipment to which correlations must be made when other equipments are developed for use. For more details about the Dynaflect and Falling Weight Deflectometer refer to Yoder and Witzack (1975), Salter (1979), and Snaith (1985).

Measuring with the Deflection Beam is rather slow; a disadvantage which is overcome by the use of any of the two equipments mentioned above. However, one other equipment which gives results as accurate as those of the Deflection Beam is the Deflectograph, which was originally developed in France as La Croix Deflectograph. The TRRL has since modified this and it is simply called the Deflectograph. It measures deflections on both wheel paths as against one wheel path at a time for the deflection beam. It travels at a speed of 30km/hr. The reader is referred to Salter (1979), Snaith (1985) Kennedy (1978), and Kennedy et al. (1978), for more details on the Deflectograph.

The results of the deflection measurement can be used in determining the remaining service life of a pavement so that with comparison with the desired life it can be determined if a pavement is (i) still sound and does not require any form of intervention, (ii) weak and requires overlay, and (iii) has outlived its service life and requires further investigation as to the manner of failure and region of the pavement in which the failure has occurred.

Overlay Design with the Deflection Beam Measurements

The main use of the deflection measurements, apart from the determination of the structural integrity of the pavement and its remaining service life, is for the determination of the overlay thickness required for a weakened pavement.

It is worth noting at this point that though designing overlays through deflection measurements has been proved to be more rational, it may not be necessary to determine deflections before an overlay is designed, since this can be done by using the conventional pavement design procedures. See for example the procedures detailed in the Asphalt Institute’s Manual Series 17 (MS-17). This MS-17 has been developed to provide the state-of-the-practice for evaluating and designing asphalt overlays for both asphalt and concrete pavements. Emphasis has been placed on alternatives to combine sound pavement management principles, accurate distress identification, and a detailed structural analysis for an asphalt overlay design to carry the projected vehicular loadings

SOLUTIONS

Having highlighted some inadequacies in the practice of civil engineering in Nigeria, it will only be proper to proffer solutions that help guard against them. In the view of the presenter, the general solutions are re-education and continuing education. Re-education here means attendance of short courses and seminars. Continuing education here means being in touch with new developments in the profession, as published in indexed journals and magazines. In addition to this is attendance of reputable international conferences. It is to be admitted that international journals, magazines and conferences proceedings are more qualitative than those within Nigeria. A lot can be gotten from the internet these days as sources of knowledge. In fact the internet is loaded with virtual libraries from which literature can be obtained at little or no cost.

It is to be noted that the presenter has not assumed complete ignorance of the audience or the generality of Nigerian civil engineers regarding the inadequacies discussed herein, but has only brought to the fore certain issues that need to be addressed in order to move civil engineering forward in the country. To many civil engineers in the audience and in the larger body of Nigerian engineers, much of (if not all) the presentation may not be news, but it is felt that presenting it will be a tonic for those who already know what to do and for those to whom this presentation is an eye-opener, to avoid these inadequacies and hence prevent avoidable failures of civil engineering infrastructural works in Nigeria.

CHARGE TO THE NICE

The NICE is advised to organise on a regular basis re-educational courses for practicing engineers. Resource persons can be drawn from the academia, from within and outside the country. There is also the need to sponsor initiatives to work out appropriate standards and codes of practice for the Nigeria setting. Much of what are used in the country at present are those developed in developed countries, some of which are not directly applicable or not applicable at all to the Nigerian setting. For example, the latest pavement design code used in the UK is usable only for traffic growth rate of 2%. It is advised that to use it, recourse has to be taken to UK’s Transport Research Laboratory for monographs for other growth rates.

CONCLUSION

The foregoing has been a presentation on inadequacies in civil engineering practice in Nigeria, and problems that arise from them as perceived by the presenter. A brief a tour has been taken through some cases to drive home the need to re-order practice in the right and appropriate directions. The cases that have been used are those of highway engineering specifically; materials’ testing, earthworks estimation, pavement design, and pavement maintenance. A charge is made to the NICE for concerted effort towards developing standards and codes of practice appropriate for Nigeria The NICE is also advised to organize courses regularly to re-educate practicing engineers to update their knowledge and enhance the practice of the civil engineering profession in Nigeria. The need is advocated to engage in research and development activities specifically in the area of estimating appropriate ESAL for vehicles in Nigeria.

ACKNOWLEDGEMENT

The presenter wishes to thank the Warri Chapter of the NICE for granting the permission to present the material herein, being a modification of an earlier presentation at the 2008 Annual Seminar (State of Engineering Education and Practice in Nigeria) of the Chapter, held on 19th July, 2008 at the Shell Club, Warri.

REFERENCES

ARA, Inc. (2006) Mechanistic Empirical Pavement Guide., Version 0.910. Arizona State University, Phoenix, Arizona.

ARA, Inc. ERES Consultants Division (2003) Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures. NCHRP Research Rep.1-37A. Transportation Research Board, National Research Council, Washington, D.C.

Department of Transport (1987) Structural Design of New Road Pavement. Department of Transport Highways and Traffic Department Standard HD 14/97. HMSO, London.

Kennedy, C.K. (1978). “Pavement Deflection: Operating Procedures for Use in the United Kingdom.” TRRL Laboratory Report 835, Transport Road and Research Laboratory Crowthorne.

Kennedy, C.K. Fevre, P. and Clarke, C.S. (1978) “Pavement Deflection” Equipment for Measurement in the United Kingdom.” TRRL Laboratory Report 834, Transport Road and Research Laboratory Crowthorne.

Kennedy, C.K. and Lister N.W. (1978). “Prediction of Pavement Performance and the Design

of Overlays.” TRRL Laboratory Report 833, Transport Road and Research Laboratory Corwthorne.

Olowosulu, A. T. (2005) A Framework for the Development of Mechanistic-Empirical

Pavement Design for Tropical Climate. Nigerian Journal of Civil Engineering, Vol 5(1).

Powell, W.D., Potter, J.F., Mayhew, H.C. and Nunn, M.E. (1984) The structural design of bituminous pavements. Dept. of Transport and Environment, TRRL report LR 1132. Transport Road and Research Laboratory Crowthorne

Road Research Laboratory (1999) A Guide to the Pavement Evaluation and Maintenance of Bitumen-Surfaced Roads in Tropical and Sub-Tropical Countries. Overseas Road Note 18. Transport Research Laboratory, Crowthorne.

Salter, R.J. (1979). “Highway Design and Construction” Macmillan, London.

Smith, H.R. and Jones, C.R. (1980) “Measurement of Pavement Deflection in Tropical and Sub-tropical climates”. TRRL Laboratory Report 935. Transport Road and Research Laboratory Crowthorne.

Snaith, M.S. (1985) “Pavement Condition Assessment Techniques” Journal of the Inst. of Highways and Transportation, London 32:1.

The Asphalt Institute (1999) Thickness Design – Full Depth Asphalt Pavement Structures for Highways and Streets. Manual Series MS-1. Ninth Edition. The Asphalt Institute, College Park, Maryland.

The Asphalt Institute (1999) Asphalt Overlays for Highway and Street Rehabilitation Manual Series MS-17. Second Edition (Revised). The Asphalt Institute, College Park,Maryland.

The Asphalt Institute (1999) Thickness Design–Asphalt Pavements for Heavy Wheel Loads. Manual Series MS-23. First Edition. The Asphalt Institute, College Park, Maryland.

Yoder, E.L. and Witzack, M.W. (1975) “Principles of Pavement Design” John Wiley, New York. Second Edition.

APPENDIX

This paper was first presented in 2010 during the Nigerian Institution of Civil Engineers National conference by late D. o. Osula. May his soul rest in peace.

1 COMMENT

  1. The use of these foreign indices can be problematic. Reason being that they were defined on conditions which are either not known to us or may not apply to our environment.
    There are reasons why the American system may use a different terminology from the imperial, it’s not just a choice of language for the sake of it. These could be such that they are easily intuitive to its intended use or user.
    From every indication, it is obvious that the writer did a thorough job on this presentation. Some of the points highlighted/emphasized could be proprietary to this presenter as observations from field applications. He only struggled to give the credit to what was in existence, rather than putting them in the context of personal observations.
    One way to this is to define a unique index or set of indices with reference to their boundry of application and publishing them as such, rather give credit to who knows next to nothing about your work.
    Kudos!

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