Road and Transportation Engineering

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Discrete Element Method for Slope Stability Analysis
(Addis Ababa University, 2003-07) Kebede, Dawit; Boled, . Girma
A static DEM has been presented to solve slope stability analyses. The method consists of discretizing the soil mass into blocks which are joined by Winkler springs. From relation of forces with stiffness and displacement, sets of simultaneous equations are solved to find displacements and stresses. The local stresses are used to calculate factor of safety while the displacement fields are used for predicting the critical failure surface. Example problems have been solved using DEM and the results have shown the potential of the method for slope stability analysis. Comparisons of the present model between limit equilibrium methods, FEM and with DEM models by other authors are made .The results suggest that DEM methods can be used both to predict the critical slip surface and give a factor of safety and that these outputs closely agree with the conventional limit equilibrium methods and the more rigorous FEMs.
Pavement Distresses on Addis Ababa City Arterial Roads, Causes and Maintenance Options
(Addis Ababa University, 2005-04) Alebachew, Fiker; Berhanu, Girma(PhD)
Paved roads in tropical and sub tropical climates often deteriorate in different ways to those in temperate regions, because of the harsh climatic conditions, lack of proper design and quality control, high loads and inadequate assessment for identifying causes of distresses before carrying out maintenance and rehabilitation. A pavement distress that occurs at the surface can have a number of different causes which must be properly identified before corrective action is taken. The visible manifestation of the problem at the surface may be the same; however, the solution for each cause may be different. Therefore, if the remedial action is to be effective, the cause of the problem must be identified and corrected. The present road condition of Addis Ababa shows rapid deterioration. The severity of pavement distresses is even more critical on the major arterial roads were the traffic volume of busses, heavy trucks, passenger vehicles and taxies is comparatively 61 higher than other road network. Such severe distresses summed up with inadequate road signs and markings are resulting congestion and consequently causing further deterioration of roads due to maximum static load sustained from the vehicular traffic waiting in a queue on the pavement. This research mainly focuses on making assessment of asphalt pavement condition, identifying causes of pavement distress and proposing maintenance options for the arterial roads of Addis Ababa. These roads are most widely utilized, and therefore prone to severe distress and consequently exhibiting repeated maintenance and repair. Visual distress assessment, roughness tests, DCP tests and other necessary laboratory investigations were carried out on selected test sections in order to have better understanding of the pavement response and come up with identification of probable causes. Major causes of pavement distress associated with load, drainage and durability are tried to be identified. A statistical analysis is also made to check how each investigation results showing pavement response variables and material properties interact with each other to identify the cause of distresses. The visual survey analysis indicates that almost all test roads have very low PCI value. Raveling, corrugation, Bumps and sags are the most dominant type of distresses constituting more than 75% of the distress densities in the arterial road network. The majority of test sections showing low PCI values are observed to have a base material of low bearing value sandwiched between the asphalt and other pavement layers. The investigation and analysis also showed that moisture and drainage associated distresses are predominant in the arterial roads and most likely on the whole network as well. Moreover, it is also observed that most of the existing pavements lack structural adequacy and hence require reconstruction than doing a routine maintenance and/or rehabilitation.
Design Consistency of Horizontal Alignments on Two - Lane Trunk Roads
(Addis Ababa University, 2007-02) Mekonnen, Behailu; Berhanu, Girma(PhD)
Design consistency is the conformance of highway’s geometric and operational features with driver’s expectancy. A technique to evaluate the consistency of a design is to evaluate changes in operating speeds along an alignment. To use operating speed as a consistency tool requires the ability to accurately predict speeds as a function of the roadway geometry. The current Ethiopian Roads Authority geometric design manual is based on the design speed concept. However, due to the constraints resulting from roadway elements, right-of-way, and environmental features, consistency in operating speed cannot be guaranteed. In order to make informed decisions to ensure highway geometric design consistency, the consistency of geometric design of operating speed on simple curve and tangent section was studied. Forty three sections for both of horizontal curve sections and tangent sections were selected, within easy reach of Addis Ababa. Roadway geometric design variables were obtained from design documents and through field measurements. The speeds of passenger cars, buses, and trucks were measured on each curve and its approaching tangent, under dry day time condition. This study was focused on two major issues, in evaluating the geometric design consistency of the selected alignments and in developing operating speed predicting models for the selected sections. Therefore, the results obtained from consistency evaluation shows that four sections between simple curves and tangents were in poor conditions. Whereas, consistency evaluation between design speed and operating speed shows that thirty seven sections in horizontal curves and thirty four sections in tangents sections was in a poor conditions. Two models were found for horizontal curves and tangents. Model found for the horizontal curves were governed by the combination of grade and superelevation. Furthermore model for tangent section were governed by grade.
Investgation of Effects of Imperfection and Their Significance in Analysis Results
(Addis Ababa University, 2007-02) Tadesse, Haimanot; Zekeria, Adil(PhD)
Structural systems are prone to global as well as member imperfections in geometry. These imperfections are accounted for when considering structural stability and strength requirements of both sway and non-sway frames. In the first part of this thesis, stability of imperfect systems is examined. With the intention of understanding the ideas necessary to tackle more practical aspects of instability, stability of equilibrium are first introduced by analysis of the behavior of some simple mechanical systems. Existence of imperfection cause the maximum load to be attained to fall below the critical value and the larger the imperfection, the larger is this reduction. The bifurcation point defines the form of instability of a structural system. For simple mechanical systems, the behavior of the imperfect system is governed by the magnitude and the sign of the imperfection and also the critical load of the system without imperfection. In systems with more than one degree of freedom, it is the fundamental mode and load which governs the elastic portion of the behavior frames possessing imperfection. The pattern of imperfection of form and loading, considered as a whole determines the mode of buckling. To evaluate strength requirements of imperfect structural systems, the imperfection effects are quantified in terms of an initial sway imperfection at the base of the column and then converted to equivalent horizontal forces. Analysis is carried out which includes these equivalent horizontal forces and the maximum bending moment in columns and beams for frames with varying number of bays and number of stories are examined. For a fixed number of stories, the effect on maximum bending moment in beams decreases with increasing number of bays. The effect on columns is not as large as that on beams but is still significant for high rise buildings. For fixed number of bays the percentage increase rises with the story height.
Effect of Different Types of Filler Materials on Characteristics of Hot-Mix- Asphalt Concrete
(Addis Ababa University, 2007-02) Berhe, Zemichael; Berhanu, Girma(PhD)
Various studies have shown that the properties of mineral fillers have significant effect on the performance of asphalt concrete pavements. This study was intended to investigate the effect of different types of mineral fillers in hot-mix-asphalt performance. The mineral fillers, with different percentages by total weight of the mixture, used in the study were crushed stone, volcanic-cinder, and limestone passing 0.075mm sieve. Using the different types and contents of the mineral fillers, a number of trial mixes have been prepared using the Marshal Mix design procedure to arrive at asphalt concrete mixtures that fulfill the Marshal criteria. The effects of each mineral filler type on Marshal Properties of the asphalt mixtures at their respective optimum asphalt content were evaluated and possible basis for such difference in properties was discussed. Using the different mineral fillers at their respective optimum asphalt content, specimens were prepared to investigate moisture susceptibility of asphalt mixtures. The Marshal Immersion test method was adopted to determine the moisture effect of mixtures. The test results show that all mineral fillers do have an effect on various mixture properties. Mixtures prepared with volcanic-cinder require higher asphalt content to fulfill all the Marshal requirements. This makes these mixtures more costly from practical point of view. Higher stability values were however, obtained by mixes with volcanic-cinder as compared to limestone and crushed stone fillers. Moreover, higher retained stability values are obtained by mixes prepared with limestone and volcanic–cinder as compared to the widely used crushed stone. The dynamic moduli values, estimated using the formula developed by the Asphalt Institute, were higher for mixtures prepared with limestone fillers and crushed stone as compared to volcanic-cinder at higher filler contents starting from 5% in the mixture. x From the study, similar trend of mixture properties, particularly Marshal properties, were observed for mixes made with limestone and crushed stone fillers as compared to that of volcanic-cinder. This indicates that limestone can be used as a substitute for the widely used crushed stone where available. This, of course, requires further investigation that better simulates the field condition. On the other hand, inconsistent mixture properties were observed from mixes made with volcanic-cinder. This also entails further investigation if it is deemed to be used as filler materials in asphalt concrete. Generally, different characteristics of bituminous mixtures were observed by varying the fillers in the mixture by type and content. This indicates that, mineral fillers are recognized as an important ingredient in the mixture property. From the test results obtained, there is a common trend in obtaining different mixture properties with varying filler content, which shows, there exists optimum filler content that best mix performance could be achieved. The results of this research work is hoped to be used as the basis for further investigation on the effects of mineral fillers and improve asphalt concrete mixtures as well as find alternative materials.
Capacity Evaluation of Roundabout Junctions In Addis Ababa
(Addis Ababa University, 2007-04) Getachew, Tewodros; Berhanu, Girma(PhD)
This thesis addresses the most important element of operational performance of roundabout traffic intersections in Addis Ababa: capacity analysis. The relation between a roundabout performance measure and capacity is often expressed in terms of degree of saturation (Demand volume – Capacity ratio). The capacity analysis is done based on empirical gap – acceptance method that is adopted by aaSIDRA software. The necessary geometric data for the analysis (average entry width, circulatory road width, number of entry and circulatory lanes, and island diameter), traffic movement data with vehicle characteristics and pedestrians volume were collected from 10 roundabouts. These 10 roundabouts represent different sizes of inscribed circle diameters of roundabouts, which are directly related to their approach leg numbers (3 leg, 4 legs, 5 legs and 6 legs). aaSIDRA software capacity analysis results indicated that out of 10 roundabouts 6 of them have greater than 0.85 degree of saturation. This 0.85 value is recommended by analysis procedure of some model countries such as Australia, Germany, United Kingdom and U.S.A. Whose roundabouts are designed to operate at no more than 85 percents of their estimated capacity. Approach entry capacity has been analyzed for all 10 roundabouts at their legs and with curve –fitting techniques. Effective capacity verses geometric parameters relationship have been developed in order to find out the causes of their over Saturation (v/c ratio greater than 0.85) And the result indicates; number of entry lanes, number of circulatory lanes, high traffic flow and pedestrian volumes are the major causes of their over saturation. Furthermore, The chart is developed using the parameters number of entry lanes, number of circulatory lanes and opposing circulatory flows, which can assist in designing of roundabouts and forecasting their capacity
Causes of Road Traffic Accidents and Possible Counter Measures on Addis Ababa-Shashemene Roads
(Addis Ababa University, 2007-04) Segni, Getu; Berhanu, Girma(PhD)
Road traffic accidents occur as a result of several factors associated with the traffic system, namely: road users, road environment and vehicles. In year 2004/5, 93% of all accidents involved human factors, 5% accounted for vehicle factors, and 2% were associated with road environments according to the Federal police report. Despite having low road network density and vehicle ownership, Ethiopia has a relatively high accident records. In this regards, the traffic accident death rate per ten thousand motor vehicles in 2001/02-2004/5 was in the range of 129 and 145. Road accidents are concentrated in few of the regions in the country. The capital city of Addis Ababa and Oromia region account for 58 per cent of all fatal accidents and two thirds of all injuries. This study is carried out to identify black spots and possible causes of road traffic accidents and to identify low cost engineering countermeasures. The research is done by reviewing road traffic growth, the existing legislative framework of road transport, and road traffic accidents for the last four years in the country. Previous studies were also reviewed having access to the information in other countries in order to understand the existing knowledge and experiences. Road and traffic data were collected from fieldwork and accident data were gathered from pertinent police stations. Each accident spots was measured with reference to kilo meter post that is available in the Addis Ababa-Shashemene road. A total of 1108 reported accidents were collected out of which 309 were fatal accidents, 206 were serious injuries, and 86 were slight injuries and 507 were property damages. Statistical analysis was made on the collected accident data. The characteristics of accident in built-up (towns) and non built up (rural) areas were tabulated and analyzed separately. Fortysix per cent of the accidents occurred in built-up areas, which covered only 17.7 percent of the study road length. Pedestrian accidents and multiple-vehicle accidents were dominated in urban areas. Single vehicle non-pedestrian and rollover accidents were higher in non-built-up areas. Fifty-two percent of the accidents occurred at tangent and level section of the roads. This is associated with speed limit violation. The results of the study indicated that increases in accident rates were highly associated with gradient and sharp curves. ADT, numbers of x lanes and grade have positive relationships with accident rates i.e. the section with less traffic, lanes and grades resulted in less accident rates whenever these variables increased. Similarly, accidents were plotted using GIS software and nine accident black spots were identified. Out of these, six were on scheme roads and three were at intersections. Greater or equal to ninety percentile of accident rate for schemes and junctions were applied in order to select these dangerous sections. At ninety percentile, rate of accident was 3.459 Mvkm for scheme. Six road sections were found above either of the two accident rates. In case of junctions, ninety percentile was 0.728626 Mv junctions. Three spots had above the ninth percentile value and considered for in-depth study. The main causes of accidents at black spots were identified to be unavailability of proper pedestrian facilities, high volume of pedestrian traffic, drivers’ fatigue, lack of awareness of traffic rules and regulations, and violation of speed limit. In addition, densities of accidents per kilometer were verified as a function of access points in towns. Narrow bridges, inadequate sight distances at curves, road curvature, no proper traffic signs, and faded road markings are usually causes of accidents. Finally, low cost engineering measures are recommended to reduce the number of road accidents at identified black spots and other sections. However, the effect should be evaluated
Analysis and Design of Struts to Node Connection of Space Truss In Buildings
(Addis Ababa University, 2007-10) Worku, Emebet; Tebedge, Negussie(Prossefor)
Construction of special structures such as space frames and trusses, shells and domes is to provide large spaces with aesthetically pleasing appearance. Such structures are nowadays finding wide applications in our country. This demonstrated that number of clients interested in the space truss technology is increasing by the day. But considering the lack of standards and codes and training for such special structures design and analysis, currently most of such works are done by foreign engineering companies. These special structures are not yet locally manufactured. This study has as the objective to design, analyze and manufacture space truss made of steel, which acts as a network of struts and nodes with emphasis on the nodes. This may serve as a reference for designers and also to identify how and in what way the nodes can be produced by locally available material and manufacturing means. It is hoped that this will make the construction cost for steel space frames lower and the supervision easier due to the use of readily available local manufacturing methods.
Investigation into the appropriate laboratory testing procedures for the determination of the index properties of the Lateritic Soils of Western Ethiopia (Nedjo-Jarso-Begi Road area)
(Addis Ababa University, 2009-11) Million, Wossen; Haile, Mesele (PhD)
The appropriate laboratory testing procedures while carrying out index property tests of lateritic soils found in western Ethiopia (Nedjo, Jarso and Begi areas) have been investigated. Classification and composition of these soils have also been studied. The X-Ray Diffraction (XRD) analyses revealed that the soils in these areas are composed of minerals of Kaolinite and Smectite groups; such as Kaolinite, Quartz, Hematite, Vermiculite, Dickite, Borax, Illite, Nacrite. The X-Ray Fluorescent (XRF) analysis showed that there is a high concentration of sesquioxide minerals and there is no amorphous material present in the soils. Comparison between the moisture contents determined using air drying (or alternatively 50oC oven drying temperature) and that of 105oC oven drying temperatures indicates that there is no significant amount of structural water; however, comparing to the non-lateritic soils from Addis Ababa, the western Ethiopia lateritic soils have some amount of structural water or water of hydration. In the analysis of Atterberg Limits, in majority of the soils difference was observed between the Atterberg Limits obtained from test on a specimen mixed for 5min and that of 30min, this indicates that the cementation of the clay particles is to be disaggregated with higher mixing time. Analysis of specific gravities of the soils using various pretreatment and testing procedures showed that, increase in drying temperature from its in situ condition to an air-dried or equivalent of 50oC oven drying temperature and further to 105oC oven drying temperature reduces specific gravity of the soils. Analyses of the grain-size distributions (grading curves) with respect to the effects of different testing procedures (pre-test treatment methods), the effects of specific gravity variation within a sample, and the variation of sample location /depth/ and other physical properties indicated that the soils were not homogeneous within the laterite zone. The dry sample preparation and testing procedures tends to decrease the percentage of coarser particles as the coarser particles became highly fractured during the pulverization process. As a result these dry sieving techniques were found to be inappropriate. The analyses of the grading curves using mass proportion and the modified grading curve using volume proportion, which uses separate specific gravity, showed that the two grading curves are nearly the same; hence, the need of modifying the grading curves by volume proportion is not as such important especially when wet sieving method is used. Moreover, the analysis of grading curves with respect to sampling depth showed that, generally, the soils become coarser as the sampling depth increases. This confirms that the degree of weathering decreases with depth. Soil classification using Unified Soil Classification System (USCS), AASHTO Classification System, Wesley’s Classification Method (classification using mineralogical composition) and soil grouping using genetic basis and soil forming factors were analyzed. According to the USCS chart the soils under investigation falls in the MH zone, which means that the soils have ‘poor’ engineering properties that are considered unsuitable for various engineering purposes. However, in practice, such soils frequently have good engineering properties especially for construction of sub grades and embankments. Contrary to the USCS, the AASHTO Classification System classify majority of the soils under sub group A-2-7 with a group index less than 4, which mean the soils are good sub grades and embankments construction materials. Using the Wesley’s Classification Method the soils fall under Group C, sub-group (c). Soils under this group have good engineering properties. The soils under investigation have fallen under ferrisols group where erosion has kept pace with profile development. The analysis of the test results obtained from different laboratory testing procedures used for moisture content, plasticity tests, grain-size analysis and specific gravity tests for the lateritic soils found in Western Ethiopia has shown that the soils are sensitive to the type of testing procedures as a result an appropriate laboratory testing procedures attached in Appendix-A are proposed.
Blending of Cinder With Fine Grained Soil to be Used as Sub-Base Materials (The Case of Butajira Gubre Road)
(Addis Ababa University, 2011-07) Eshete, Yitayou; Seged, Hadush (PhD)
In road construction, the use of locally available materials should be made as much as possible. However, these materials are not always suitable and when appropriate material cannot be found in areas close to the construction site, very high prices have to be paid with significant time delays and cost increases. In many parts of Ethiopia, there is widely distributed cinder gravel. However, this material has the problem of compaction due to its light weight, its rough circular surface and its high porosity. This thesis deals with investigating the performance of mechanically stabilized natural cinder gravels to be used as road sub-base material. To achieve the Ethiopia Road Authority manual specification, the cinder gravel was blended with some trail proportion of 0, 5, 10, 15, 20, and 25 % of fine-grained soil by mass and different tests including grain size distribution, Atterberg Limit, compaction, CBR, LAA, absorption and linear Shrinkage are conducted in the laboratory. Based on the laboratory test results it is shown that, from both MDD- percent of fine-grained soil curve and CBR-percent of fine-grained soil curve, the optimum amount of fine-grained soil required in order to improve its properties is 19 % by mass proportion. KEY WORDS: sub-base, Cinder Gravel, Blending of sub-base material, Optimum finegrained soil Content, Gradation, Arithmetical proportioning.
Assessing & Quantifing the Level of Traffic Congestion at Major Intersections in Addis Ababa (A Case for East-West Corridor)
(Addis Ababa University, 2011-09) Taddesse, Wondwossen; Gebresenbet, Girma (Professor)
Traffic Congestion is an ever growing chronic problem in the transportation system soon after the invention and mass production of automobiles. All major cities both in developed and developing countries are facing the problem due to increasing travel demand which follows economic and population growth. Traffic congestion directly affects commuters with an increased travel time, excessive delay in a queue, increased fuel cost, delay for important appointment and job, loss in productive hours; and it indirectly affects the living standard and the environment as well. Hence, traffic congestion cause upon road users and cities to incur a significant amount of money for both economic and social costs. Quantifying the level of the traffic congestion and understanding how much effect and cost are being incurred due to traffic congestion; hence, will be important for making improvement decisions and evaluate implemented mitigation measures. Following the economic and population growth in Addis Ababa, traffic congestion problem has emerged and the problem is even growing faster. In this study, the level of the traffic congestion in Addis Ababa city was quantified using travel time approach. The city’s one of the most congested East-West corridor was considered and travel time, traffic volume, and vehicle occupancy data were collected at four midblock and four intersections. Accordingly, the travel rate, the delay rate, total travel delay (Veh-Min and Per-min), buffer index and planning time index were calculated. And also, the average hourly travel rate is correlated with the average hourly traffic accident data and congestion spots and accident black spots were plotted on the GIS map to see the relationship between the traffic accident and traffic congestion. Accordingly, the result showed that on average about 18,000 Veh-min or 38 Veh-day and about 169,000 Per-min or 352-person-day are wasted at each major intersection entry and the city incurs annually about 5-8 Million Birr per intersection only for vehicle and fuel cost. The result also showed that the city’s traffic accident rate correlated with travel rate better than traffic volume and the congestion spots identified from questionnaire data conside with the black spots identified by the national road safety agency.
Supply Chain Assesment of Sesame Oilseed From Humera to Djibouti Port
(Addis Ababa University, 2011-09) Kemal, Shikur; Girma, Gebresenbet (Prof.)
Ethiopian’s sesame oils product demand has been growing in the last couple of years. In order to stay competitive and cope up with the world market, problems on productivity, logistics, quality, infrastructures and others should be given due attention so that the country can use its potential on this sector and bring foreign currency, which will have huge influence for the economic development. Therefore, it is crucial to study the supply chain of sesame from farm to port in order to point out bottlenecks and proposes mitigation measures. The study was focused mainly on Kafta-Humera woreda where the survey was conducted using questionnaires to gather information from stakeholders such as farmers, retailers, exporters, transistors and ECX officials. Farmers stated that they are encountered with shortage of capital/lack of loan services, high price of inputs and labor, poor roads, poor network system for information exchange, collision between retailers to deny them fair price. As to the retailers the main problem that they face were shortage of capital and credit services to purchase sesame, poor quality sesame supplied by farmers, poor network system to exchange information, delay at ECX due to problems of weighbridge and automated system failure costs them expensive transport prices and waste of time and energy and unawareness on how much tax is enforced on them. Exporters stated that they face problems like forced to pay high transport prices due to delay at ECX, less quality of sesame from anticipated, in accuracy of weighbridge system, poor roads to Port Sudan that impose extra transportation and storage cost, problems of theft and adulteration along route to Djibouti, delay of vehicles at customs branch offices due to automated system failure, delay of vehicles due to improper schedule of vessels and shortage of containers at Djibouti port. Solutions recommended are improving credit services, building capacity of ECX, improving road, storage and network system conditions, controlling theft and adulteration, containerizing sesame at exporter’s warehouse, improving conditions at port are believed to improve the supply chain of sesame.
Methodology for Traffic Safety Audit and Inspection of Bridges
(Addis Ababa University, 2011-09) Eshetu, Tegegne; Birhanu, Girma(PhD)
Bridges are structures including supports erected over a depression or an obstruction for carrying traffic and other moving loads. They are crucial elements of the road design elements and transportation infrastructure. There are around 3,100 bridges registered in Ethiopia in Bridge Management System. Although a considerable research has been carried out on Traffic safety on highways and Road Safety Audit as a whole, very little work has been done on traffic safety Audit and Inspection of bridges. Most of the inspections of bridges concentrate on the structural defects of bridges leaving the safety aspect of the bridge and approach roadway as a secondary concern. Bridges and bridge approaches have been identified as one of the leading locations for severe, single-vehicle crashes. There are many bridges and culverts on the highway system in different parts of Ethiopia. Most of the bridges have rigid rails and often span a potentially hazardous feature. This thesis presented a methodology for traffic safety audit and inspection of bridges. Checklists were prepared for each stage of design starting from planning stage through construction stage so that safety elements aren’t overlooked by the designer. The checklist incorporates important safety features to be checked such as, the adequacy of bridge width, the adequacy of pedestrian width, the application of constant width for the approach roadway as well as bridge, adverse geometric alignment at the bridge approach roadways, and the incorporation of crashworthy transitions, approach guardrail and end treatments. Sample projects which are found at different stages of design were selected for an implementation exercise. As part of this thesis, bridge safety inspection sheet was developed for the safety inspection of existing bridges. It was assumed that the results will create awareness to most bridge engineers who deal with the structural assessment of existing bridges. Bridges located on Modjo – Awassa road were used for developing the bridge safety inspection sheets. None of these bridges has end treatments, approach guardrail and transition section. The major defects noted include, cross section constriction, poor approach alignment, sight distance constraints and high fill heights without safety barrier on the approaches. Inspection procedures and data sheets are prepared based on intensive literature review and field inspection of existing bridges. Bridge engineers and inspectors are advised to use the developed safety inspection sheet as part of their routine structural inspection of existing bridges.
Optimizing of Freight Transport and City Logistics Activities in Addis Ababa
(AAU, 2011-09) Nebyi, Gebremariam; Girma, Gebresenbet (PhD)
Though goods distribution is an important part of activity in urban life as it plays a vital role in urban economy in terms of income generation and employment opportunities, nowadays urban freight distribution is creating many challenges like environmental pollution, congestion and traffic accident in the growing cities in developing nations. ABSTRACT Thus, this research paper aim is to optimize freight transport and city logistics activities in the city of Addis Ababa so that goods can be distributed to the city center, without jeopardizing the lives of city dwellers, depleting environment and also enabling a good economic efficiency of freight transport and maximized profit for stakeholders. According to the traffic data collected from field survey and the historical traffic data collected from ERA, on average 19,088 and 18,428 freight vehicles per day enter and leave the city of Addis Ababa respectively out of which, 66.6%, 19.6%, 6.59%, 4.33% and 2.93% enters through gate of Debrezeit, Jimma, Gojjam, Debrebrhan and Ambo respectively where, 27.94%, 27.83%, 23.67% and 20.56% were Medium Trucks, Heavy Trucks, Small Trucks and Truck Trailers Respectively and similarly 67.43%, 16.30%, 8.24%, 4.06% and 3.97% exits through the gate of Debrezeit, Jimma, Gojjam, Debrebrhan and Ambo respectively accounting 27.74%, 27.59%, 23.07% and 21.60% Medium Trucks, Heavy Trucks, Small Trucks and Truck Trailers Respectively . Future prospects from the study reveal that freight traffic entering to the city and leaving the city will grow at an average rate of 10.03% and 9.63% respectively and as a result the entering and leaving freight traffic will raise to 90,633 and 86,124 respectively by 2015. Out of the total vehicles driven within the city, only 7.53% were freight transporting vehicles accounting the least share and 36.61% were cars taking the largest share. In view of load factor which is in terms of weight, it was found that due to limited application of city logistics measures within the city freight transporting vehicles operate at an average load factor of 53% which leads to increased transport cost. Within the city more than 146 warehouses and 1 freight terminal are available where 59% of the warehouses are located within the main city center and major sub-centers of the city attracting huge freight vehicles and operating at a poor level of service. Regarding to the terminal delay, it was found that terminals cause vehicles to delay for about 120 days. According to the study, commodity type, season and transparency of the customers, capacity of custom officers and transitors and capacity of the terminal were the basic factors that affect delay of terminals. To minimize the negative impacts, five optimum freight terminal locations were selected with the help of factor rating method and this newly selected terminals are expected to minimize the negative impacts of the freight distribution as they minimize entry of freight vehicles to the city center and terminal delay. It is perceived that, high increase in the road freight transport coupled with the little awareness of city logistics measures and concepts within the city and the country in general are the main reasons that are causing problem within the city. Hence, strengthening freight transport data base management system, creation of awareness regarding the concept of city logistics with its advantages and environmental impacts among stakeholders and further researches on possibility cooperative freight delivery system, coordinated goods movement and investigation of the possibility to use other ports other than port of Djibouti for import and export activities should be the task of researchers and concerned authorities before the problems get worse.
Costing Road Traffic Accidents In Ethiopia
(Addis Ababa University, 2011-10) Mohammed, Murad; Berhanu, Girma(PhD)
Road accidents have many negative costs that are regarded as socio-economic costs. In recent years, road traffic accidents have caused a significant and increasing socio-economic loss in developing countries in general and in Ethiopia in particular. With the high growth of road accidents throughout the developing world, it is essential that adequate sums of money are spent in dealing with the problem. In the absence of an estimate of accident-related economic issues, it is difficult to identify the sums of money that should be invested each year on road safety countermeasures. Nevertheless, the estimation of the national explicit costs of road accidents as well as the implicit value of the accidents is rarely highlighted to policy makers. This paper aims to review accident costing methodologies in developing countries and apply it in estimating the economic loss of road traffic accidents in the country, Ethiopia. And also it focuses to insight the challenges of estimating the costs of road accidents in low income countries where vital registration and relevant statistics concerning road accidents are scarce. A feasible method for costing road accidents in such instances is identified, and the severity and costliness of road accidents in the country is demonstrated. Accident data and cost figures of 2009/10 are considered to make the estimation of the annual traffic accident cost in Ethiopia. The analysis shows, among other things, road accidents erode more than 0.49% of the country’s Gross Domestic Product (GDP).
Standardization of Guidelines for Railway Track Infrastructure Subsystem for Railway System of Ethiopia
(Addis Ababa University, 2012-01) Gebeyehu, Yeserah; Abesha, Berhanu (PhD)
Railway transportation, which is needed in the achievement of effective development, is an efficient, cost-effective and it is environmental friendly transport system. In addition to the low railway network connectivity in Ethiopia like other developing countries, the available one is not modern; has low capacity and is insufficient to facilitate transit trade; and also Ethiopian railway transport has not standardized guidelines to design the system. In this study an attempt was made to standardize guidelines for railway track infrastructures specifically track geometric parameters and track structural elements for conventional lines in Ethiopia. To achieve such objectives the research had a methodology of a task involving literature review; discussion and comparison of different country standardization practice; and different data collection that contribute for standardization of guidelines for railway system in Ethiopia. Standardization of guidelines for different track infrastructure subsystems for Ethiopia context was done based on topography, climatic condition and availability of track construction material, and different literature reviews. Track cant of a normal limiting value of 160 mm was recommended to reduce or eliminate lateral acceleration created due to small curve in difficult topography of Ethiopia. In addition a cant excess of as small as 70 mm was recommended in avoiding damage of low rail by heavy freight train; and correspondingly this can be achieved by increasing the value of cant deficiency for fast train. A gradient of up to 3.5% and/or greater value was recommended for lines constrained by topography. Even if the selection of steel rail grade is based on avoiding rail wear and rolling contact fatigue; standard steel rail strength i.e. R260 is recommended for all lines including for the whole range of curvatures due to high investment cost of higher quality steel grade that are recommended for sharp curves (curves are suffering from high rail wear). On the other hand, the recommended method of selecting fastening systems is a matter of satisfying safety of the lines. The specification of ballast and subballast depend on the availability of track construction material; and the track construction material availability in Ethiopia is, more or less, not a problem in construction industry even in the eastern part of Ethiopia where inadequacy of construction material are expected. An attempt was made to find a suitable range of ballast ii gradation which fulfills the objective of good strength (well graded) without significant reduction in permeability of ballast (uniform graded) using a coefficient of uniformity between 2.2 and 2.6, moderately graded ballast was recommended. In addition the specification of subballast material was determined based on filter principle of drainage criteria using subgrade material size distribution. The problematic subgrade soil, placed under subballast, should be replaced or improved to achieve the required strength characteristics of subgrade layers. The appropriate type of tests was selected to define the characteristics of each track substructure layers (ballast, subballast and subgrade soil). Key Words: Track, Cant, Cant Deficiency, Cant Excess, Rail, Fastener, Sleeper, Ballast, Subballast, Subgrade and Safety
Optimizing Logistic Chain of Animal Transport and Meat Distribution: Studies on Livestock Markets and Abattoirs in Addis Ababa City
(Addis Ababa University, 2012-09) Gudeta, Beshada; Gebresenbet, Girma (Professor)
Ethiopia has the largest livestock population in Africa. Livestock production is an integral part of the country’s agricultural production system and the livestock sector constitutes a significant share of the country’s GDP. As one of the milestones for the overall livelihood in the country, livestock serves as a source of draught power for the rural farming population, supplies farm families with milk, meat, manure, serves as a source of cash income, and plays significantly in the social and cultural values of the society. Despite the importance of the livestock sector to the agricultural and national economy in the country, the sector is underdeveloped and underutilized. The challenges facing the transport and handling of slaughter animals was thought to be one of the obstacles to the livestock sector shadowing the role it can play in the national economy. This study aimed at mapping out the animal supply chain from regions to the terminal markets in Addis Ababa and further to the Abattoirs, identifying and mapping the existing livestock market and Abattoirs in the city, mapping out the activities and processes at the abattoir, determining possible locations of the livestock markets and abattoirs in the city, and evaluating the existing meat distribution in the capital in addition to pointing out possible recommendation for efficient transport and handling of slaughter animals in the city and from different parts of the country to the city. Slaughter animals in Addis Ababa are brought from different parts of the country passing different hierarchy of markets. Isuzu trucks, not designed for the purpose of transporting animals, are used for transporting the slaughter animals from various regions to the terminal market in Addis Ababa although animal trekking was also another mode of animal transport to the city especially for shorter journeys. Considerable problems in handling and treatment of animals during loading, transport, and unloading were observed and the process as a whole was not in line with the animal handling guidelines of the country due to various technical and institutional problems. Addis Ababa Abattoir Enterprise(AAAE) was the biggest Abattoir in the city responsible to provide 85% of the city’s meat demand ( both in slaughtering and distributing meat) where the remaining 15% share of the meat consumption was covered by Kara-Alo Abattoir and Abattoirs iii in Oromia regional state nearby the capital. The meat distribution process with respect to route choice, delivery order, vehicle scheduling and management, sanitation problems were inefficient in minimizing distribution costs, delivering quality and healthy meat to the customers, and on time delivery of the product to the customers. The result of route optimization using RouteLogiX Professional V 5.5 (5 Professional) showed that the distribution routes and delivery orders were not optimized and up to 41% savings in distribution distance with an average saving of 12.33% and up to 39.68% savings in distribution times with an average saving of 13.58% would be achieved if optimized routes were used. The existing livestock market centers and Abattoirs in Addis Ababa were evaluated with respect to their location, standard and effect on the community nearby them. The result of location analysis showed that most of the market centers and Abattoirs are located at city centers with fewer standards than required affecting the health of the inhabitants negatively. Location factor rating technique was used as a tool to determine optimum positions of livestock market centers and Abattoirs at optimum locations that will resolve the existing challenges and contribute to the well being of the inhabitants as well.
Investigation of the Performance of Unsealed Road Sub Base Materials Used as Wearing Course of Gravel Road (In the Case of Kamashi –Yaso Road)
(Addis Ababa University, 2012-09) Merga, Simeneh; Teklu, Bikila (PhD)
A good road structure may help in reducing the number of accidents. Wearing course is the top layer of the road structure which is the layer exposed to the vehicle tyre and environment. The international roughness index and Present Serviceability Index are both indices that can be used as indicator of road roughness and serviceability. Objective of the study is primarily to determine the performance and the durability, serviceability and service life of unsealed gravel road wearing course above sub grade. In evaluating the serviceability of the road, roughness is an important indicator of pavement riding comfort and safety. It is condition indicator that should be carefully considered when evaluating pavement performance. At the same time, the use of roughness measurements plays a critical role in the pavement management system. There are many devices used for roughness evaluation. In this thesis, roughness measurement was done by Merlin manual instrument. The methodology used to carry out the thesis work is carry the field data measurement for roughness and gathering user assessment for the case study site and taking sample data of soil for strength test of CBR. International roughness index was measured by using Merlin roughness index measuring instrument. And used for calculating present serviceability index as independent parameter. Both international roughness index and present serviceability index were measured along 200m section of the road for about 19.7km of the study route. This studies only focuses on one type of road which was gravel pavement located on western part of Ethiopia in Benishagul Gumuz regional state in Kamashi Zonal state. The work has generated that this unsealed gravel road is running with in the design limit without sever deterioration as the result of serviceability, user assessment, CBR strength test and roughness value shows.
Software Development for the AASHTO and ERA Flexible Pavement Design Methods
(Addis Ababa University, 2012-09) Setegn, Amare; Teklu, Bikila (PhD)
In Ethiopia the number and type of traffic increases and the change is alarming. This leads to the construction of road infrastructures which needs economical and safe design of roads. Nowadays, flexible pavement roads and surface failure before the expected design period has become a critical issue in our country. The design in our country is based on the prevailing condition of soil and materials report using the Ethiopian Roads Authority ( ) Pavement Design Manual where the results obtained will be compared with that of the Structural Design Pavement manual. Finally, the thickness obtained using both design guides will be compared. And it is known that pavement thickness design in our country is manual based. Manual design method has a drawback in avoiding human mistake, error and doing many alternatives for comparison as flexible pavement design involves different nomograph, charts, tables and formulas so it is cumbersome and time taking practice which may result in unsafe or uneconomical design. The development of the software is using MATLABR2008b programming language. And the goals achieved are the thicknesses of surface, base and subbase layers of flexible pavement roads are determined and different design charts, default values and tables are digitalized. Furthermore, comparison between AASHTO and ERA methods in terms of thickness and construction cost can be made to select the best design alternative. Besides, the designer or researcher can do as many alternatives as needed in short time. The result obtained by the developed software (AASHERA) is verified by comparing with the manuals and examples from different books. And the analysis results turn out to be successful when it is compared with the manuals and books calculation. KEY WORDS: AASHTO Flexible Pavement Design, ERA Flexible Pavement Design, AASHTO Road Test, AASHERA
Evaluation and Development of Floriculture Supply Chain in Ethiopia, to Attenuate Environmental Impact and Logistics Cost
(Addis Ababa University, 2013-01) Hailemichael, Daniel; Gebresenbet, Girma (Professor)
Ethiopia is now Africa‟s second largest flower exporter after Kenya, with its export earnings growing by 500% over the past year. In 2008, there were 81 flower farms employing around 50,000 workers (over 70% women). Ethiopia‟s flower exports reached 100 million USD and the industry is one of the top four sources of foreign exchange for the country. In less than a decade of experience, Ethiopia ranks second in Africa for flower exports, and fifth in Extra-EU exporters to the EU market. Annual average growth in number of firms and exports in 2003 to 2008 is around 380% and 638% respectively. Ethiopian growers can produce a very high quality product, which has a big demand on the market in the advantage of higher altitude of the country but at this moment it is still quiet important to bring this product correctly and on time into that market. This can be achieved by designing a good logistic system. That is why the main objective of this research is being describing the supply chain of floriculture in Ethiopia, determine main bottlenecks and develop efficient methodology in line with coordination possibilities and route optimization to reduce logistic cost and environmental impact. The majority of the farms are located in about 50 km radius of the capital city, Addis Ababa. These cluster areas will create an opportunity for collaboration among producers. From analysis results there is a probability of collaboration between farms found in these three clusters in transporting their products inland and they can save the inland transport cost significantly. Supply chain of floriculture in Ethiopia consists of different activities categorized as farm operations, inland transport, and cargo activities. In the farm activities the operation starts from cutting. Cutting is done by leaving two leaves at bottom of the rose tree. After cutting, the stem is collected in water bucket and taken to pre-cooling room and kept for 8-10hrs at temperature of 4-6 oc. After pre-cooling the sorting and packaging process begins. The packed flowers kept in cold room for 1 and ½ days at temperature of 2oc. Finally the bundles of flowers are placed in carton ( 23 bundles/carton) and placed back to the cold room. The next activity is inland transport operation and the last activity is the cargo transport to the Dutch auction market or other whole sellers. Most farms in Ethiopia use ground water for irrigation purpose this will create continues depletion of ground water. The use of chemicals will also create contamination of ground water and streams near to the farm locations are also getting contaminated by the chemicals used even if the effect is not significant the proper use of chemicals and safe disposal of west should be made by trained professionals for chemical protection. The chemical sprayers wear mask during chemical spraying but most of the workers are not trained for this special purpose. This will put the health of the workers in danger.

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