Unrealistic or incomplete estimates of traffic characteristics during design process will affectrndetermination of pavement type, performance of the pavement structures for the design lifernas well as construction and maintenance cost. Thus, accurate estimation of traffic loading isrnneeded for a better design of pavement structures, easy of construction and maintenance asrnwell as cost effective.rnThree road projects here selected for this study, the one Shashemene-Dodola pavement designrnwhich is overestimated future traffic and result high capital cost of construction (increase usernof construction materials, resources). The other two projects Alemgena-Butajira andrnDebrebrihan-Karakore pavement design are underestimated future traffic and it pre-maturedrnpavement failure which results a high capital cost of maintenance and increases vehiclernoperation cost.rnThis study assesses the existing practice of traffic forecasting for pavement design andrnrecommend potential improvements of procedures. This process and its results have beenrncoordinated in order to be incorporated in traffic volume estimation. Two traffic growth raternestimation method is adopted i.e, Regression and Elasticity Analysis from traffic counts andrnfor determination of forecasted traffic volume.rnThe study result indicates, the change between actual traffic volume which is counted duringrnthe road service time by Ethiopian Roads Authority and traffic volume estimation of using thernabove methods is within 0% to 4% whereas, the change between actual traffic and designrntraffic is -87% to 51%.rnFrom the result of calculated cumulative standard axel load and determining traffic class ofrnthe pavement, analyzing the difference in traffic class of the design traffic and study traffic isrncarried out. Finally determining the impact of inaccurate traffic volume and loading estimationrnon pavement performance and analyses additional cost of construction and maintenance duernto inaccurate traffic volume estimation.