PARAMETRIC MODELLING ON THE RELATIONSHIPS BETWEEN ATTERBERG LIMITS AND COMPACTION CHARACTERISTICS OF FINE-GRAINED SOILS

Compaction is one of the essential engineering techniques, performed to assure the stability of soils based on specified strength. However, in most construction projects such as large-scale projects, obtaining the desired compaction characteristics, namely optimum moisture content (OMC) and maximum dry density (MDD), becomes time-consuming. In this case, predicting the compaction characteristics from the Atterberg's limits that involve a more straightforward and quicker method of testing becomes a vital task. This study focused on obtaining valid correlations between Atterberg's limit parameters and compaction characteristics of fine-grained soils. A series of laboratory tests for 50 samples conducted for the investigation. Statistical relationships of all the parameters were analyzed. The laboratory test results indicated that both OMC and MDD showed a strong correlation with LL and PL together using multiple linear regressions than with single parameters from single linear regression. Therefore, the study concluded that during the prediction of OMC and MDD from Atterberg's limits, the combined parameters of Atterberg's limits should be used rather than single parameters. It is recommended, the result of this research could be applied in different civil engineering practices, directly related to the parameters to be known

Comparative Analysis on Road Users’ Cost Using HDM-4 Software and Manual Technique: A Case of Addis Ababa-Adama Expressway

Continuous changes in vehicle technology, road condition, traffic compositions initiate the change or updating of road users’ cost models. So that it needs to practice a continuous revision or update periodically for realistic estimation of costs and benefits. This paper presented the relationship and comparison between road users’ cost along Addis Ababa-Adama newly constructed expressway using the Highway Development and Management (HDM-4) Software and manually using formulations developed in the Portuguese model. The method started with data collection. All input data were collected from primary and secondary sources. The primary data utilized an interview, and secondary data were sourced out from pertinent documents, both published and unpublished. More data were gathered that related to vehicles. The vehicles using the road are classified based on the manual from the Ethiopian Road Authority as cars, utilities, small bus, large bus, small truck, medium truck, heavy truck, and truck trailer. The collected data have been input into the HDM-4 interface; the output of the analysis was vehicle operating costs, travel time, and road users’ cost as a summation. Using manual technique and HDM-4 Software, Birr 128.62/km/vehicle and Birr 139.23/km/vehicle, respectively, were found from road users’ costs analysis. The result shows the difference of Birr 10.61. Also, the correlation coefficient of 0.75 is determined, which shows that the two results of road users’ costs are highly related. As a result, the study reveals that the application of HDM-4 Software and the manual technique formulations from the Portuguese model can be adopted interchangeably to calculate Road Users’ Cost of road sections in Ethiopia. Hence, the study results are expected to be an eye-opener for a future similar project by the concerned agencies

Geotechnical Conditions and Stability Analysis of Landslide Prone Area A Case Study in Bonga Town, South-Western Ethiopia

There were several slides and associated ground subsidence which brought significant impact on the cracking of walls and floor of several private and governmental buildings in Bonga Town. The principal and secondary roads were also affected by subsidence with vertical displacement up to 1m which hampered the traffic in the town. Water pipelines along the road were disturbed by the sliding which was later repaired. Cracking of the walls and floor of more than 120 private residences and more than 10 government buildings were recorded. The main highway that connects Bonga-TepiMasha via Alamo and Gatiba has been disrupted at four locations. This resulted in hampering traffic for several days. This research aimed to evaluate the cause and failure mechanism as well as the stability condition of the landslides. The study involved the investigation of the Geotechnical parameters of soil and the terrain characteristics to be used for the stability analysis of the slope, including distribution and characteristics of soils, the groundwater table, and the depth and geometry of the failures. The Slope stability analysis is supplemented by using Geo-studio 2004 software. Soil samples were collected and were tested for grain size analysis, distribution analysis (sieve & hydrometer) plastic limit, liquid limit, plasticity index, water content, unit weight of soil, specific gravity, and shear strength parameters following the ASTM procedures. Based on the findings, the landslides were triggered by heavy rainfall. Therefore, the main factors controlling the stability of the slope are soil type and characteristics, slope angle, water (surface and groundwater), and slope steepness. The design of the retaining wall is recommended to mitigate the impact of landslides in the study area.&nbsp

Analysis of influential factors affecting workers’ productivity on highway construction projects during Covid-19 pandemic in Cagayan Valley Region, Philippines

In highway construction projects, labor-oriented work is an integral part of the management process, requiring analysis of factors affecting labor productivity during the Covid-19 pandemic. This research identified 53 influential factors affecting construction labor productivity at selected cities and towns in Cagayan Valley Region, Philippines. Due to the pandemic, the construction industries incurred substantial profit losses. More so, the construction workers are too much affected because of the Enhance Community Quarantine (ECQ) imposed by the local government. Results indicated there was laxity on the Covid-19 protocols. No health worker in the project site ranked the highest in the health & safety factor group with an RII of 0.97 and ranked 1st among 53 factors on the different groups. Besides, no safety engineer was assigned to the projects and ranked 2nd with an RII of 0.93. Among the 7 groups of factors, the health and safety group ranked 1st with 0.81, followed by the schedule compression group with an RII of 0.78. Hence, these two groups of factors have a strong relationship, as evidenced by the number of workers reduced. It was learned that the contractors’ strategy was to increase the number of working days to cope with their schedules. Hypothesis testing supported that there are various significant factors influencing labor productivity loss during the Covid-19 pandemic, as suggested by more than 50% of the respondents

Assessment of Factors Affecting Labor Productivity on Road Construction Projects in Oromia Region, Bale Zone

Road construction in Ethiopia is booming and radiating from Addis Ababa towards North-East and East-West directions to fulfill its long-term development program. Transportation is a prime mover to all sectors in the country to uplift the economic activities of the populace in the locality. In most countries, experience and related literature have revealed that road construction labor costs accounted for 30-60% of the total cost of a project, depending on the terrain and source of materials, labor, and equipment to be utilized. Therefore, construction labor productivity plays a vital role in the performance and profitability of road construction projects. Road sector construction projects in Ethiopia are means through which development strategies are achieved. This research study gives insight on the assessment of the factors affecting labor productivity in road construction projects through a structured questionnaire survey of 83 respondents working on construction road projects in Oromia Region, Bale Zone. Respondents were required to rate how the 61 factors affecting labor productivity with respect to the importance and frequency of occurrence. Understanding these factors is helpful for the construction professionals who work on the initial phase of construction planning in order to efficiently deliver the project plan and to solve poor labor productivity. The results of this survey were then analyzed using the Relative Importance Index (RII) and ranked. The reliability of these 61 factors for assessing the effect on labor productivity was tested by Chronbach’s alpha measurement, and the results indicated that the 30 factors tested are reliable (α= 0.973), and checked by SPSS. The result of this analysis showed that there are 11 groups that have significant impacts on the labor productivity ranked as Material and Equipment Factor with RII=0.819, Manpower and WorkForce Factor with RII=0.764, Management Factor with RII=0.737, Quality Factors with RII=0.720, Supervision Factor with RII=0.699, Safety Factor with RII=0.691, Motivation Factor with RII=0.682, Schedule Factor with RII=0.647, Political Factor with RII=0.620, Natural and environmental Factor with RII=0.566 and Cultural and Religious Factor with RII=0.541. Based on the results of this research study, the top factors that affect labor productivity includes Lack of experience of labor, Material construction shortage, Lack of labor skills, Accident, Tools and Equipment shortage, Labor’s bad habit, Poor site management, Lack of Labor surveillance, Payment delay and Ignore safety precautions. Therefore, this research study suggests that the contractors should assign project managers and construction supervisors with sufficient managerial skills in road construction projects so that when there are any problems which may arise, it would be acted and solved immediately at the project site. On the other hand, the role of the Ethiopian government in project implementation is very significant, which requires proper attention to the productivity issue to enforce hard and fast laws and regulation which help to obtain productive workforce in the road construction industry

Influence of Subsurface Courses Materials On Pavement Performance: A Case Study in Yebu-Agaro Road

The properties of subsurface materials would vary from place to place while it is true the performance of pavement along the route also differs. The research study had been undertaken at the Yebu-Agaro road section with the main objective to determine the Influence of Subgrade Soil on pavement performance. In order to realize the desired objective, a systematic methodology was adopted which includes field investigation, field test, and laboratory tests. While the purposive sampling method was used to extract soil samples from the road section that are severely damaged showing different failure types and non-distress surfaces. Those severe types of failures observed along the road section are reflective crack, pothole, rutting, alligator crack, and block crack. From these failure types, five representative samples were extracted at different locations along the failures section and one non-distress pavement of the road section using a manual hand auger. The analyses of soil samples were carried out based on the Geotechnical properties such as wash gradation, Atterberg limit, and Modified proctor test, California Bearing Ratio (CBR) and field test, as well as Axle load analysis. It was found out that the liquid limit of subgrade soil varies from 33% -60.5% and the plasticity index from 20.3% -30.1% while there was a significant increase in moisture content at the field and observed beyond the OMC in the laboratory result due to the distress of pavement affected by water infiltration through cracks, that tend to reduce the dry density. The recorded soaked CBR values of subgrade soil materials range between 8% -13%, which was below the 15% minimum value specified by the ERA manual. However, the existing CBR values of the subgrade soils indicate a poor material used for pavement structures. According to ASSHTO, the soil is classified as A-2-6 and A-7-6 category which means the existing soils are fair to poor as a sub-grade material while USCS classification shows that the soil falls into the SC group. In addition, the failures that are frequently observed on the road surface were significantly influenced by subgrade soil. For the sub-base layer materials, it was noted to have satisfied the minimum requirements as compared with standard specification, except deficiency of its thickness. For the base course materials, inferior qualities of material were used in some sections. The overall results showed that heavy vehicles or traffic loads are one of the major causes of road failure along the study road section. Hence, the influence of other factors such as poor drainage courses, level of groundwater table, variety of geologic materials along the road route, and poor construction materials should be thoroughly addressed before the start of the rehabilitation of the road section in the future. Finally, a possible remedial measure is recommended for every observed failure or distress on the pavement condition of the study area in order to sustain the design life of the pavement.&nbsp

Assessment on Materials Quality Control Implementation of Building Construction Projects and Workmanship: A Case Study of Ambo University

Quality of material issues have been a significant source of concern since the dawn of recorded history. Building materials are essential and should be performed according to standard specifications because they cover around 60% of the project cost. Prior to project construction, specific codes, standards, and specifications should be available. Using all required materials does not guarantee a sound building appearance or function. Even with suitable materials, workmanship, and supervision, unexpected output can affect a building. Quality workmanship is a comprehensive approach to bolstering building durability, serviceability, and safety. The study evaluated Ambo University's building construction materials and quality. Convenience and quota sampling techniques were collected from all contractors and consultants involved in building construction via questionnaires and interviews. A comprehensive literature review identified 15 major factors affecting building construction materials quality and workmanship, and respondents ranked them in the order of importance. Defects in existing buildings and ongoing projects had observed due to non-compliance with construction materials and workmanship based on specifications and standards. The results indicated that Ambo University building has no defect-free structure, including the degree and type of defects vary. A 94% of the studied buildings had moisture leakage, plastering defects, paint peeling, and cracks. Hence, the consultants and Ambo University project representatives should adhere with the standard specifications, and must exercise their profession according to the ethical code of conduct. All of these, it will play a vital role in the success of construction projects

Cost and Benefit Analysis of Rigid and Flexible Pavement: A Case Study at Chancho –Derba-Becho Road Project

Road construction projects have been implemented all over Ethiopia as part of the national development plan. Roads are one of the country’s basic infrastructural facilities where high amounts of the budget allocated every fiscal year planning period. Since the cost comprises of a large portion of government investment, a careful evaluation of the alternatives is of utmost importance to make the right choice for a particular project. In the history of Ethiopia's road development program, almost all of the road pavements are flexible, and it demands high foreign currency for asphalt material importing from abroad. In addition, flexible pavement needs to be maintained and rehabilitated within a few years after its initial construction. In view of the emerging cement factories and the availability of cement in Ethiopia, it is practical to consider rigid pavement as one of the alternatives. Relative to this, the research project was conducted with the main objective of identifying the cost and benefit of rigid and flexible pavements at the Chancho-Derba-Becho road project, North Showa Zone in Oromia. The research work had been focused on the specific objectives to determine and compare the life cycle costs of rigid and flexible pavements and to investigate all other qualitative merits of rigid and flexible pavement. To achieve these objectives, a review of related literature, design and specifications, observations and investigations of the actual pavement construction projects, evaluation of life cycle costs, the future value of money and present worth calculation were undertaken with an analysis period of 40 years. While the data considered was gathered through investigation at the actual rigid and flexible pavement projects, an examination of specifications, drawings and pavement design, Ethiopian Road Authority manuals, rehabilitation, and maintenance strategy. In this regard, the cost parameters investigated are initial construction cost, maintenance cost, rehabilitation cost, user’s cost, and salvage value, in addition to other qualitative and quantitative data. Based on the results of the research project, it revealed that the initial cost of rigid pavement was almost twice of the flexible pavement, but in the long run, the cost of flexible pavement per kilometer was found out to have 7.9 Million ETB more than the rigid pavement because of the incurring costs of maintenance through its design life. Therefore, it is suggested that Portland Cement Concrete Pavement (PCCP) shall be used in pavement construction to cater to local material requirements.&nbsp

Assessment on the effects of weather change on road construction planning at some selected projects in Addis Ababa and Oromia

Road construction in Ethiopia is in high demand to meet its short and long-term goals in infrastructure development programs. The road network is constructed radiating outwards North-South and East-West direction of the Capital City. Some projects are experiencing weather malady due to changing weather conditions in project locations. The study area of this research was focused on some selected projects in Addis Ababa and Oromia. The research had been addressed the effects of changes in weather in the three project planning phases, namely conception planning, design planning, and construction planning. A quantitative research design was used in this study. A literature review was undertaken and the result of which showed that the effects of weather changes are not extensively researched in the construction industry and there are limited references on the effects of weather change within the road construction industry. Sample data were obtained from sixty-three (63) construction practitioners through questionnaires, which were mailed to prospective respondents to assess their opinions. Questions were subdivided into three relevant areas covering demographics, experience with weather change factors, and the effects of weather change on road construction project planning. The study found that the effects of weather change on road construction project planning are similar to those found in other construction industries. The effects of weather change factors on road project planning vary with planning phases. These weather change factors as well as their effects were listed and ranked based on their frequency of occurrence and mean score. An independent sample t-test was used to compare respondents’ opinions on weather change effects between the two sample groups taken in Addis Ababa and part of Oromia. A partial correlation was also employed to identify the relationship between weather change factors and their effect on road construction project planning using SPSS-20. Delay of site preparation activities as a result of weather change on road project conception planning phase has a mean score of 4.30 Addis Ababa and 4.00 in for Oromia, while the influence of weather change on the selection and specification of construction materials for road project design planning phase has the highest mean score of 4.23 for Addis Ababa and 4.03 for Oromia. The effect of weather change on road workers' physiological comfort and quality of work for the road project construction planning phase has the highest mean score of 4.80 and 4.58 in Addis Ababa and Oromia, respectively. The study concludes with recommendations for potential research and with useful information and considerations on the effects of weather change on road construction project planning for construction professionals and project managers

Causes of Delays During Construction Phase of Road Projects due to the Failures of Contractor, Consultant, and Employer in Addis Ababa City Road Authority

Construction delay considered as one of the most recurring problems in the implementation of construction projects. It is widely known to have an adverse impact on project success in terms of time, quality, and cost. The effect of construction delay is not only confined to the construction industry but also its influence on the overall economy of a country like Ethiopia. This research was conducted to assess the causes of excessive delays in the completion of road projects during the construction phase due to the failures of Employer, Consultant, and Contractor in Addis Ababa City Road Authority projects. Spearman rank correlation coefficient from the Relative Importance Index (RII) analysis was used to test the agreement between different groups of respondents who participated in the questionnaire survey and to rank the three construction parties according to their responsibility area and importance as perceived by the respondents which factor causing the delay of road projects. This research identified sixty-five (65) causes of delay. There were fifty-one (51) valid questionnaires received back from Contractors, Consultants, and Employer (AACRA). Based on the results, the contractors have the highest percentage of responsibility area that causes the delay of about 40%. While the second was on the part of the Employer, which comprised 26.15%, and the consultant which placed third of 23.08%. On the other hand, there were 10.77% of the respondents attested that the Shared groups (3-parties) have the responsibility area which causes project delay during the implementation phase. About this, the research study identified and ranked the top ten factors causing delays of construction projects in Addis Ababa City Road Authority. Poor financial control of the project ranked 1st with Relative Importance Index (RII) of 0.905. Difficulties in financing projects by contractors ranked 2nd with the Relative Importance Index (RII) of 0.854. Type of project bidding and award (lowest bidder) ranked 3rd with an RII of 0.850. Poor site management and supervision of contractors ranked 4th with an RII of 0.839. Selecting inappropriate contractors ranked 5th with an RII of 0.823. Lack of high-technology mechanical equipment ranked 6th with an RII of 0.819. Inaccurate initial project scope estimate and Ineffective project scheduling ranked 7th and 8th with an RII of 0.803. Weak control of the project progress ranked 9th with an RII of 0.788. And the Contractor’s staff is not adequately trained in professional construction management techniques ranked 10th with an RII of 0.784. Therefore, it concluded that the main party Contractor did not perform properly his duties and obligations leading to the main contributory factor causing the failure of the project.&nbsp